D-Link NetDefend DFL-260E User manual

Network Security Solution http://www.dlink.com
NetDefendOS
Ver.2.40.00
Network Security Firewall
User Manual
Security
Security

User Manual
DFL-260E/860E/1660/2560/2560G
NetDefendOS Version 2.40.00
D-Link Corporation
No. 289, Sinhu 3rd Rd, Neihu District, Taipei City 114, Taiwan R.O.C.
http://www.DLink.com
Published 2011-09-06
Copyright ©2011

User Manual
DFL-260E/860E/1660/2560/2560G
NetDefendOS Version 2.40.00
Published 2011-09-06
Copyright © 2011
Copyright Notice
This publication, including all photographs, illustrations and software, is protected under
international copyright laws, with all rights reserved. Neither this manual, nor any of the material
contained herein, may be reproduced without the written consent of D-Link.
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implied warranties of merchantability or fitness for a particular purpose. D-Link reserves the right to
revise this publication and to make changes from time to time in the content hereof without any
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DAMAGES OF ANY CHARACTER (E.G. DAMAGES FOR LOSS OF PROFIT, SOFTWARE
RESTORATION, WORK STOPPAGE, LOSS OF SAVED DATA OR ANY OTHER
COMMERCIAL DAMAGES OR LOSSES) RESULTING FROM THE APPLICATION OR
IMPROPER USE OF THE D-LINK PRODUCT OR FAILURE OF THE PRODUCT, EVEN IF
D-LINK IS INFORMED OF THE POSSIBILITY OF SUCH DAMAGES. FURTHERMORE,
D-LINK WILL NOT BE LIABLE FOR THIRD-PARTY CLAIMS AGAINST CUSTOMER FOR
LOSSES OR DAMAGES. D-LINK WILL IN NO EVENT BE LIABLE FOR ANY DAMAGES IN
EXCESS OF THE AMOUNT D-LINK RECEIVED FROM THE END-USER FOR THE
PRODUCT.

Table of Contents
Preface ...............................................................................................................15
1. NetDefendOS Overview ....................................................................................17
1.1. Features ................................................................................................17
1.2. NetDefendOS Architecture ......................................................................20
1.2.1. State-based Architecture ...............................................................20
1.2.2. NetDefendOS Building Blocks .......................................................20
1.2.3. Basic Packet Flow ........................................................................21
1.3. NetDefendOS State Engine Packet Flow .....................................................24
2. Management and Maintenance ............................................................................29
2.1. Managing NetDefendOS ..........................................................................29
2.1.1. Overview ...................................................................................29
2.1.2. The Default Administrator Account .................................................30
2.1.3. The Web Interface .......................................................................30
2.1.4. The CLI .....................................................................................36
2.1.5. CLI Scripts .................................................................................44
2.1.6. Secure Copy ...............................................................................48
2.1.7. The Console Boot Menu ...............................................................50
2.1.8. Management Advanced Settings .....................................................52
2.1.9. Working with Configurations .........................................................53
2.2. Events and Logging ................................................................................59
2.2.1. Overview ...................................................................................59
2.2.2. Log Messages .............................................................................59
2.2.3. Creating Log Receivers .................................................................60
2.2.4. Logging to MemoryLogReceiver ....................................................60
2.2.5. Logging to Syslog Hosts ...............................................................60
2.2.6. Severity Filter and Message Exceptions ...........................................62
2.2.7. SNMP Traps ...............................................................................62
2.2.8. Advanced Log Settings .................................................................64
2.3. RADIUS Accounting ..............................................................................65
2.3.1. Overview ...................................................................................65
2.3.2. RADIUS Accounting Messages ......................................................65
2.3.3. Interim Accounting Messages ........................................................67
2.3.4. Activating RADIUS Accounting .....................................................67
2.3.5. RADIUS Accounting Security ........................................................68
2.3.6. RADIUS Accounting and High Availability ......................................68
2.3.7. Handling Unresponsive RADIUS Servers .........................................68
2.3.8. Accounting and System Shutdowns .................................................69
2.3.9. Limitations with NAT ...................................................................69
2.3.10. RADIUS Advanced Settings ........................................................69
2.4. Monitoring ............................................................................................71
2.4.1. The Link Monitor ........................................................................71
2.4.2. SNMP Monitoring .......................................................................73
2.4.3. Hardware Monitoring ...................................................................76
2.4.4. Memory Monitoring Settings .........................................................78
2.5. The pcapdump Command ........................................................................80
2.6. Maintenance ..........................................................................................83
2.6.1. Auto-Update Mechanism ...............................................................83
2.6.2. Backing Up Configurations ...........................................................83
2.6.3. Restore to Factory Defaults ............................................................85
3. Fundamentals ...................................................................................................88
3.1. The Address Book ..................................................................................88
3.1.1. Overview ...................................................................................88
3.1.2. IP Addresses ...............................................................................88
3.1.3. Ethernet Addresses .......................................................................90
3.1.4. Address Groups ...........................................................................91
3.1.5. Auto-Generated Address Objects ....................................................92
3.1.6. Address Book Folders ...................................................................92
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3.2. IPv6 Support .........................................................................................93
3.3. Services ................................................................................................98
3.3.1. Overview ...................................................................................98
3.3.2. Creating Custom Services ..............................................................99
3.3.3. ICMP Services ..........................................................................102
3.3.4. Custom IP Protocol Services ........................................................104
3.3.5. Service Groups ..........................................................................104
3.3.6. Custom Service Timeouts ............................................................105
3.4. Interfaces ............................................................................................106
3.4.1. Overview .................................................................................106
3.4.2. Ethernet Interfaces .....................................................................108
3.4.3. VLAN .....................................................................................115
3.4.4. PPPoE .....................................................................................118
3.4.5. GRE Tunnels ............................................................................120
3.4.6. Interface Groups ........................................................................124
3.5. ARP ..................................................................................................126
3.5.1. Overview .................................................................................126
3.5.2. The NetDefendOS ARP Cache .....................................................126
3.5.3. Creating ARP Objects .................................................................128
3.5.4. Using ARP Advanced Settings .....................................................130
3.5.5. ARP Advanced Settings Summary ................................................131
3.6. IP Rules .............................................................................................135
3.6.1. Security Policies ........................................................................135
3.6.2. IP Rule Evaluation .....................................................................138
3.6.3. IP Rule Actions .........................................................................139
3.6.4. Editing IP rule set Entries ............................................................140
3.6.5. IP Rule Set Folders ....................................................................141
3.6.6. Configuration Object Groups .......................................................142
3.7. Schedules ...........................................................................................146
3.8. Certificates .........................................................................................148
3.8.1. Overview .................................................................................148
3.8.2. Certificates in NetDefendOS ........................................................150
3.8.3. CA Certificate Requests ..............................................................151
3.9. Date and Time .....................................................................................153
3.9.1. Overview .................................................................................153
3.9.2. Setting Date and Time ................................................................153
3.9.3. Time Servers ............................................................................154
3.9.4. Settings Summary for Date and Time ............................................157
3.10. DNS .................................................................................................160
4. Routing .........................................................................................................164
4.1. Overview ............................................................................................164
4.2. Static Routing ......................................................................................165
4.2.1. The Principles of Routing ............................................................165
4.2.2. Static Routing ...........................................................................169
4.2.3. Route Failover ..........................................................................174
4.2.4. Host Monitoring for Route Failover ...............................................177
4.2.5. Advanced Settings for Route Failover ............................................179
4.2.6. Proxy ARP ...............................................................................180
4.3. Policy-based Routing ............................................................................183
4.4. Route Load Balancing ...........................................................................190
4.5. OSPF .................................................................................................196
4.5.1. Dynamic Routing .......................................................................196
4.5.2. OSPF Concepts .........................................................................199
4.5.3. OSPF Components .....................................................................204
4.5.4. Dynamic Routing Rules ..............................................................210
4.5.5. Setting Up OSPF .......................................................................213
4.5.6. An OSPF Example .....................................................................217
4.6. Multicast Routing .................................................................................220
4.6.1. Overview .................................................................................220
4.6.2. Multicast Forwarding with SAT Multiplex Rules .............................221
4.6.3. IGMP Configuration ..................................................................225
4.6.4. Advanced IGMP Settings ............................................................230
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4.7. Transparent Mode ................................................................................233
4.7.1. Overview .................................................................................233
4.7.2. Enabling Internet Access .............................................................238
4.7.3. Transparent Mode Scenarios ........................................................239
4.7.4. Spanning Tree BPDU Support ......................................................243
4.7.5. Advanced Settings for Transparent Mode .......................................244
5. DHCP Services ..............................................................................................249
5.1. Overview ............................................................................................249
5.2. DHCP Servers .....................................................................................250
5.2.1. Static DHCP Hosts .....................................................................253
5.2.2. Custom Options .........................................................................255
5.3. DHCP Relaying ...................................................................................256
5.3.1. DHCP Relay Advanced Settings ...................................................257
5.4. IP Pools ..............................................................................................259
6. Security Mechanisms .......................................................................................263
6.1. Access Rules .......................................................................................263
6.1.1. Overview .................................................................................263
6.1.2. IP Spoofing ..............................................................................264
6.1.3. Access Rule Settings ..................................................................264
6.2. ALGs .................................................................................................266
6.2.1. Overview .................................................................................266
6.2.2. The HTTP ALG ........................................................................267
6.2.3. The FTP ALG ...........................................................................270
6.2.4. The TFTP ALG .........................................................................279
6.2.5. The SMTP ALG ........................................................................280
6.2.6. The POP3 ALG .........................................................................289
6.2.7. The PPTP ALG .........................................................................290
6.2.8. The SIP ALG ............................................................................291
6.2.9. The H.323 ALG ........................................................................302
6.2.10. The TLS ALG .........................................................................316
6.3. Web Content Filtering ...........................................................................319
6.3.1. Overview .................................................................................319
6.3.2. Active Content Handling .............................................................319
6.3.3. Static Content Filtering ...............................................................320
6.3.4. Dynamic Web Content Filtering ...................................................322
6.4. Anti-Virus Scanning .............................................................................337
6.4.1. Overview .................................................................................337
6.4.2. Implementation .........................................................................337
6.4.3. Activating Anti-Virus Scanning ....................................................338
6.4.4. The Signature Database ..............................................................338
6.4.5. Subscribing to the D-Link Anti-Virus Service .................................339
6.4.6. Anti-Virus Options .....................................................................339
6.5. Intrusion Detection and Prevention ..........................................................343
6.5.1. Overview .................................................................................343
6.5.2. IDP Availability for D-Link Models ..............................................343
6.5.3. IDP Rules .................................................................................345
6.5.4. Insertion/Evasion Attack Prevention ..............................................347
6.5.5. IDP Pattern Matching .................................................................348
6.5.6. IDP Signature Groups .................................................................349
6.5.7. IDP Actions ..............................................................................350
6.5.8. SMTP Log Receiver for IDP Events ..............................................351
6.6. Denial-of-Service Attack Prevention ........................................................355
6.6.1. Overview .................................................................................355
6.6.2. DoS Attack Mechanisms .............................................................355
6.6.3. Ping of Death and Jolt Attacks .....................................................355
6.6.4. Fragmentation overlap attacks: Teardrop, Bonk, Boink and Nestea ......356
6.6.5. The Land and LaTierra attacks .....................................................356
6.6.6. The WinNuke attack ...................................................................356
6.6.7. Amplification attacks: Smurf, Papasmurf, Fraggle ...........................357
6.6.8. TCP SYN Flood Attacks .............................................................358
6.6.9. The Jolt2 Attack ........................................................................358
6.6.10. Distributed DoS Attacks ............................................................358
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6.7. Blacklisting Hosts and Networks .............................................................360
7. Address Translation ........................................................................................363
7.1. Overview ............................................................................................363
7.2. NAT ..................................................................................................364
7.3. NAT Pools ..........................................................................................369
7.4. SAT ...................................................................................................372
7.4.1. Translation of a Single IP Address (1:1) .........................................372
7.4.2. Translation of Multiple IP Addresses (M:N) ....................................377
7.4.3. All-to-One Mappings (N:1) .........................................................379
7.4.4. Port Translation .........................................................................381
7.4.5. Protocols Handled by SAT ..........................................................381
7.4.6. Multiple SAT Rule Matches .........................................................381
7.4.7. SAT and FwdFast Rules ..............................................................382
8. User Authentication ........................................................................................385
8.1. Overview ............................................................................................385
8.2. Authentication Setup .............................................................................387
8.2.1. Setup Summary .........................................................................387
8.2.2. The Local Database ....................................................................387
8.2.3. External RADIUS Servers ...........................................................389
8.2.4. External LDAP Servers ...............................................................389
8.2.5. Authentication Rules ..................................................................396
8.2.6. Authentication Processing ...........................................................398
8.2.7. A Group Usage Example .............................................................399
8.2.8. HTTP Authentication .................................................................399
8.3. Customizing Authentication HTML Pages ................................................404
9. VPN .............................................................................................................409
9.1. Overview ............................................................................................409
9.1.1. VPN Usage ...............................................................................409
9.1.2. VPN Encryption ........................................................................410
9.1.3. VPN Planning ...........................................................................411
9.1.4. Key Distribution ........................................................................411
9.1.5. The TLS Alternative for VPN ......................................................412
9.2. VPN Quick Start ..................................................................................413
9.2.1. IPsec LAN to LAN with Pre-shared Keys .......................................414
9.2.2. IPsec LAN to LAN with Certificates .............................................415
9.2.3. IPsec Roaming Clients with Pre-shared Keys ..................................416
9.2.4. IPsec Roaming Clients with Certificates .........................................418
9.2.5. L2TP Roaming Clients with Pre-Shared Keys .................................419
9.2.6. L2TP Roaming Clients with Certificates ........................................421
9.2.7. PPTP Roaming Clients ...............................................................421
9.3. IPsec Components ................................................................................423
9.3.1. Overview .................................................................................423
9.3.2. Internet Key Exchange (IKE) .......................................................423
9.3.3. IKE Authentication ....................................................................429
9.3.4. IPsec Protocols (ESP/AH) ...........................................................430
9.3.5. NAT Traversal ..........................................................................431
9.3.6. Algorithm Proposal Lists .............................................................433
9.3.7. Pre-shared Keys ........................................................................434
9.3.8. Identification Lists .....................................................................435
9.4. IPsec Tunnels ......................................................................................438
9.4.1. Overview .................................................................................438
9.4.2. LAN to LAN Tunnels with Pre-shared Keys ................................... 440
9.4.3. Roaming Clients ........................................................................440
9.4.4. Fetching CRLs from an alternate LDAP server ................................445
9.4.5. Troubleshooting with ikesnoop .....................................................446
9.4.6. IPsec Advanced Settings .............................................................453
9.5. PPTP/L2TP .........................................................................................457
9.5.1. PPTP Servers ............................................................................457
9.5.2. L2TP Servers ............................................................................458
9.5.3. L2TP/PPTP Server advanced settings ............................................463
9.5.4. PPTP/L2TP Clients ....................................................................463
9.6. SSL VPN ............................................................................................466
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9.6.1. Overview .................................................................................466
9.6.2. Configuring SSL VPN in NetDefendOS .........................................467
9.6.3. Installing the SSL VPN Client ......................................................469
9.6.4. Setup Example ..........................................................................472
9.7. CA Server Access ................................................................................474
9.8. VPN Troubleshooting ...........................................................................477
9.8.1. General Troubleshooting .............................................................477
9.8.2. Troubleshooting Certificates ........................................................478
9.8.3. IPsec Troubleshooting Commands ................................................478
9.8.4. Management Interface Failure with VPN ........................................479
9.8.5. Specific Error Messages ..............................................................479
9.8.6. Specific Symptoms ....................................................................482
10. Traffic Management ......................................................................................485
10.1. Traffic Shaping ..................................................................................485
10.1.1. Overview ................................................................................485
10.1.2. Traffic Shaping in NetDefendOS .................................................486
10.1.3. Simple Bandwidth Limiting .......................................................488
10.1.4. Limiting Bandwidth in Both Directions ........................................489
10.1.5. Creating Differentiated Limits Using Chains ................................. 490
10.1.6. Precedences ............................................................................492
10.1.7. Pipe Groups ............................................................................496
10.1.8. Traffic Shaping Recommendations ..............................................499
10.1.9. A Summary of Traffic Shaping ...................................................500
10.1.10. More Pipe Examples ...............................................................501
10.2. IDP Traffic Shaping ............................................................................506
10.2.1. Overview ................................................................................506
10.2.2. Setting Up IDP Traffic Shaping ..................................................506
10.2.3. Processing Flow .......................................................................507
10.2.4. The Importance of Specifying a Network ...................................... 507
10.2.5. A P2P Scenario ........................................................................508
10.2.6. Viewing Traffic Shaping Objects ................................................509
10.2.7. Guaranteeing Instead of Limiting Bandwidth ................................. 510
10.2.8. Logging .................................................................................510
10.3. Threshold Rules .................................................................................511
10.4. Server Load Balancing ........................................................................514
10.4.1. Overview ................................................................................514
10.4.2. SLB Distribution Algorithms ......................................................515
10.4.3. Selecting Stickiness ..................................................................516
10.4.4. SLB Algorithms and Stickiness ...................................................517
10.4.5. Server Health Monitoring ..........................................................518
10.4.6. Setting Up SLB_SAT Rules ........................................................519
11. High Availability ..........................................................................................523
11.1. Overview ..........................................................................................523
11.2. HA Mechanisms .................................................................................525
11.3. Setting Up HA ...................................................................................528
11.3.1. HA Hardware Setup .................................................................528
11.3.2. NetDefendOS Manual HA Setup .................................................529
11.3.3. Verifying the Cluster Functions ..................................................530
11.3.4. Unique Shared Mac Addresses ...................................................531
11.4. HA Issues .........................................................................................532
11.5. Upgrading an HA Cluster .....................................................................534
11.6. Link Monitoring and HA ......................................................................536
11.7. HA Advanced Settings ........................................................................537
12. ZoneDefense ................................................................................................539
12.1. Overview ..........................................................................................539
12.2. ZoneDefense Switches .........................................................................540
12.3. ZoneDefense Operation .......................................................................541
12.3.1. SNMP ....................................................................................541
12.3.2. Threshold Rules .......................................................................541
12.3.3. Manual Blocking and Exclude Lists .............................................541
12.3.4. ZoneDefense with Anti-Virus Scanning ........................................ 543
12.3.5. Limitations .............................................................................543
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13. Advanced Settings .........................................................................................546
13.1. IP Level Settings ................................................................................546
13.2. TCP Level Settings .............................................................................550
13.3. ICMP Level Settings ...........................................................................555
13.4. State Settings .....................................................................................556
13.5. Connection Timeout Settings ................................................................558
13.6. Length Limit Settings ..........................................................................560
13.7. Fragmentation Settings ........................................................................562
13.8. Local Fragment Reassembly Settings .....................................................566
13.9. Miscellaneous Settings ........................................................................567
A. Subscribing to Updates ...................................................................................570
B. IDP Signature Groups .....................................................................................572
C. Verified MIME filetypes .................................................................................576
D. The OSI Framework .......................................................................................580
Alphabetical Index .............................................................................................581
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List of Figures
1.1. Packet Flow Schematic Part I ...........................................................................24
1.2. Packet Flow Schematic Part II ..........................................................................25
1.3. Packet Flow Schematic Part III .........................................................................26
1.4. Expanded Apply Rules Logic ............................................................................27
3.1. VLAN Connections ......................................................................................116
3.2. An ARP Publish Ethernet Frame .....................................................................130
3.3. Simplified NetDefendOS Traffic Flow .............................................................138
4.1. A Typical Routing Scenario ...........................................................................166
4.2. Using Local IP Address with an Unbound Network ............................................168
4.3. A Route Failover Scenario for ISP Access .........................................................174
4.4. A Proxy ARP Example ..................................................................................181
4.5. The RLB Round Robin Algorithm ...................................................................191
4.6. The RLB Spillover Algorithm .........................................................................192
4.7. A Route Load Balancing Scenario ...................................................................194
4.8. A Simple OSPF Scenario ...............................................................................197
4.9. OSPF Providing Route Redundancy .................................................................198
4.10. Virtual Links Connecting Areas ....................................................................202
4.11. Virtual Links with Partitioned Backbone .........................................................203
4.12. NetDefendOS OSPF Objects ........................................................................204
4.13. Dynamic Routing Rule Objects .....................................................................211
4.14. Multicast Forwarding - No Address Translation ................................................222
4.15. Multicast Forwarding - Address Translation ....................................................224
4.16. Multicast Snoop Mode .................................................................................226
4.17. Multicast Proxy Mode .................................................................................226
4.18. Non-transparent Mode Internet Access ...........................................................238
4.19. Transparent Mode Internet Access .................................................................238
4.20. Transparent Mode Scenario 1 ........................................................................240
4.21. Transparent Mode Scenario 2 ........................................................................241
4.22. An Example BPDU Relaying Scenario ...........................................................244
5.1. DHCP Server Objects ...................................................................................253
6.1. Deploying an ALG .......................................................................................266
6.2. HTTP ALG Processing Order .........................................................................269
6.3. FTP ALG Hybrid Mode .................................................................................271
6.4. SMTP ALG Processing Order .........................................................................282
6.5. Anti-Spam Filtering ......................................................................................284
6.6. PPTP ALG Usage ........................................................................................290
6.7. TLS Termination ..........................................................................................317
6.8. Dynamic Content Filtering Flow .....................................................................323
6.9. IDP Database Updating .................................................................................344
6.10. IDP Signature Selection ...............................................................................346
7.1. NAT IP Address Translation ..........................................................................364
7.2. A NAT Example ..........................................................................................366
7.3. Anonymizing with NAT ................................................................................368
7.4. The Role of the DMZ ....................................................................................373
8.1. Normal LDAP Authentication ........................................................................395
8.2. LDAP for PPP with CHAP, MS-CHAPv1 or MS-CHAPv2 ..................................396
9.1. The AH protocol ..........................................................................................431
9.2. The ESP protocol .........................................................................................431
9.3. PPTP Client Usage .......................................................................................465
9.4. SSL VPN Browser Connection Choices ............................................................469
9.5. The SSL VPN Client Login ............................................................................470
9.6. The SSL VPN Client Statistics ........................................................................471
9.7. Certificate Validation Components ..................................................................475
10.1. Pipe Rules Determine Pipe Usage ..................................................................487
10.2. FwdFast Rules Bypass Traffic Shaping ...........................................................488
10.3. Differentiated Limits Using Chains ................................................................491
10.4. The Eight Pipe Precedences ..........................................................................492
10.5. Minimum and Maximum Pipe Precedence .......................................................494
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10.6. Traffic Grouped By IP Address .....................................................................498
10.7. A Basic Traffic Shaping Scenario ..................................................................502
10.8. IDP Traffic Shaping P2P Scenario .................................................................508
10.9. A Server Load Balancing Configuration ..........................................................514
10.10. Connections from Three Clients ...................................................................517
10.11. Stickiness and Round-Robin .......................................................................518
10.12. Stickiness and Connection-rate ....................................................................518
D.1. The 7 Layers of the OSI Model ......................................................................580
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List of Examples
1. Example Notation .............................................................................................15
2.1. Enabling remote management via HTTPS ...........................................................35
2.2. Enabling SSH Remote Access ..........................................................................41
2.3. Listing Configuration Objects ...........................................................................53
2.4. Displaying a Configuration Object .....................................................................54
2.5. Editing a Configuration Object .........................................................................55
2.6. Adding a Configuration Object .........................................................................55
2.7. Deleting a Configuration Object ........................................................................56
2.8. Undeleting a Configuration Object ....................................................................56
2.9. Listing Modified Configuration Objects ..............................................................57
2.10. Activating and Committing a Configuration .......................................................57
2.11. Enable Logging to a Syslog Host .....................................................................61
2.12. Sending SNMP Traps to an SNMP Trap Receiver ...............................................63
2.13. RADIUS Accounting Server Setup ..................................................................70
2.14. Enabling SNMP Monitoring ...........................................................................74
2.15. Performing a Complete System Backup ............................................................85
2.16. Complete Hardware Reset to Factory Defaults ...................................................85
3.1. Adding an IP Host Address ..............................................................................89
3.2. Adding an IP Network .....................................................................................89
3.3. Adding an IP Range ........................................................................................90
3.4. Deleting an Address Object ..............................................................................90
3.5. Adding an Ethernet Address .............................................................................91
3.6. Adding IPv6 Host Addresses ............................................................................93
3.7. Enabling IPv6 Globally ...................................................................................94
3.8. Enabling IPv6 on an Interface ...........................................................................94
3.9. Enabling IPv6 Advertisements ..........................................................................95
3.10. Listing the Available Services .........................................................................98
3.11. Viewing a Specific Service .............................................................................99
3.12. Creating a Custom TCP/UDP Service .............................................................102
3.13. Adding an IP Protocol Service ......................................................................104
3.14. Defining a VLAN .......................................................................................117
3.15. Configuring a PPPoE Client .........................................................................120
3.16. Creating an Interface Group ..........................................................................124
3.17. Displaying the ARP Cache ...........................................................................127
3.18. Flushing the ARP Cache ..............................................................................127
3.19. Defining a Static ARP Entry .........................................................................128
3.20. Adding an Allow IP Rule ..............................................................................141
3.21. Setting up a Time-Scheduled Security Policy ...................................................147
3.22. Uploading a Certificate ................................................................................150
3.23. Associating Certificates with IPsec Tunnels .....................................................151
3.24. Setting the Current Date and Time .................................................................153
3.25. Setting the Time Zone .................................................................................154
3.26. Enabling DST ............................................................................................154
3.27. Enabling Time Synchronization using SNTP ....................................................155
3.28. Manually Triggering a Time Synchronization ..................................................156
3.29. Modifying the Maximum Adjustment Value ....................................................156
3.30. Forcing Time Synchronization ......................................................................157
3.31. Enabling the D-Link NTP Server ...................................................................157
3.32. Configuring DNS Servers .............................................................................160
4.1. Displaying the main Routing Table ..................................................................171
4.2. Adding a Route to the main Table ...................................................................172
4.3. Displaying the Core Routes ............................................................................173
4.4. Creating a Routing Table ...............................................................................184
4.5. Adding Routes .............................................................................................184
4.6. Creating a Routing Rule ................................................................................185
4.7. Policy-based Routing with Multiple ISPs ..........................................................188
4.8. Setting Up RLB ...........................................................................................194
4.9. Creating an OSPF Router Process ...................................................................217
12

4.10. Add an OSPF Area .....................................................................................217
4.11. Add OSPF Interface Objects .........................................................................217
4.12. Import Routes from an OSPF AS into the Main Routing Table ............................ 218
4.13. Exporting the Default Route into an OSPF AS .................................................218
4.14. Forwarding of Multicast Traffic using the SAT Multiplex Rule ...........................222
4.15. Multicast Forwarding - Address Translation ....................................................224
4.16. IGMP - No Address Translation ....................................................................227
4.17. if1 Configuration ........................................................................................228
4.18. if2 Configuration - Group Translation .............................................................229
4.19. Setting up Transparent Mode for Scenario 1 ....................................................240
4.20. Setting up Transparent Mode for Scenario 2 ....................................................241
5.1. Setting up a DHCP server ..............................................................................251
5.2. Static DHCP Host Assignment ........................................................................254
5.3. Setting up a DHCP Relayer ............................................................................256
5.4. Creating an IP Pool .......................................................................................261
6.1. Setting up an Access Rule ..............................................................................265
6.2. Protecting an FTP Server with an ALG .............................................................274
6.3. Protecting FTP Clients ..................................................................................277
6.4. Protecting Phones Behind NetDefend Firewalls ..................................................305
6.5. H.323 with Private IPv4 Addresses ..................................................................306
6.6. Two Phones Behind Different NetDefend Firewalls ............................................307
6.7. Using Private IPv4 Addresses .........................................................................308
6.8. H.323 with Gatekeeper ..................................................................................309
6.9. H.323 with Gatekeeper and two NetDefend Firewalls .......................................... 311
6.10. Using the H.323 ALG in a Corporate Environment ...........................................312
6.11. Configuring remote offices for H.323 .............................................................315
6.12. Allowing the H.323 Gateway to register with the Gatekeeper .............................. 315
6.13. Stripping ActiveX and Java applets ................................................................320
6.14. Setting up a white and blacklist .....................................................................321
6.15. Enabling Dynamic Web Content Filtering .......................................................324
6.16. Enabling Audit Mode ..................................................................................326
6.17. Reclassifying a blocked site ..........................................................................327
6.18. Editing Content Filtering HTTP Banner Files ...................................................334
6.19. Activating Anti-Virus Scanning .....................................................................341
6.20. Configuring an SMTP Log Receiver ..............................................................351
6.21. Setting up IDP for a Mail Server ....................................................................352
6.22. Adding a Host to the Whitelist ......................................................................361
7.1. Specifying a NAT Rule ..................................................................................366
7.2. Using NAT Pools .........................................................................................370
7.3. Enabling Traffic to a Protected Web Server in a DMZ ......................................... 373
7.4. Enabling Traffic to a Web Server on an Internal Network .................................... 375
7.5. Translating Traffic to Multiple Protected Web Servers ........................................377
7.6. Translating Traffic to a Single Protected Web Server (N:1) ..................................380
8.1. Creating an Authentication User Group ............................................................402
8.2. User Authentication Setup for Web Access .......................................................402
8.3. Configuring a RADIUS Server .......................................................................403
8.4. Editing Content Filtering HTTP Banner Files ....................................................405
9.1. Using an Algorithm Proposal List ....................................................................433
9.2. Using a Pre-Shared key .................................................................................434
9.3. Using an Identity List ....................................................................................436
9.4. Setting up a PSK based VPN tunnel for roaming clients .......................................441
9.5. Setting up a Self-signed Certificate based VPN tunnel for roaming clients ...............441
9.6. Setting up CA Server Certificate based VPN tunnels for roaming clients .................443
9.7. Setting Up Config Mode ................................................................................445
9.8. Using Config Mode with IPsec Tunnels ............................................................445
9.9. Setting up an LDAP server .............................................................................446
9.10. Setting up a PPTP server ..............................................................................458
9.11. Setting up an L2TP server ............................................................................459
9.12. Setting up an L2TP Tunnel Over IPsec ...........................................................459
9.13. Setting Up an SSL VPN Interface ..................................................................472
10.1. Applying a Simple Bandwidth Limit ..............................................................488
10.2. Limiting Bandwidth in Both Directions ...........................................................490
User Manual
13

10.3. Setting up SLB ...........................................................................................519
12.1. A simple ZoneDefense scenario ....................................................................542
User Manual
14

Preface
Intended Audience
The target audience for this reference guide is Administrators who are responsible for configuring
and managing NetDefend Firewalls which are running the NetDefendOS operating system. This
guide assumes that the reader has some basic knowledge of networks and network security.
Text Structure and Conventions
The text is broken down into chapters and sub-sections. Numbered sub-sections are shown in the
table of contents at the beginning. An index is included at the end of the document to aid with
alphabetical lookup of subjects.
Where a "See chapter/section" link (such as: see Chapter 9, VPN) is provided in the main text, this
can be clicked to take the reader directly to that reference.
Text that may appear in the user interface of the product is designated by being in bold case. Where
a term is being introduced for the first time or being stressed it may appear in italics.
Where console interaction is shown in the main text outside of an example, it will appear in a box
with a gray background.
Where a web address reference is shown in the text, clicking it will open the specified URL in a
browser in a new window (some systems may not allow this).
For example, http://www.dlink.com.
Screenshots
This guide contains a minimum of screenshots. This is deliberate and is done because the manual
deals specifically with NetDefendOS and administrators have a choice of management user
interfaces. It was decided that the manual would be less cluttered and easier to read if it concentrated
on describing how NetDefendOS functions rather than including large numbers of screenshots
showing how the various interfaces are used. Examples are given but these are largely textual
descriptions of management interface usage.
Examples
Examples in the text are denoted by the header Example and appear with a gray background as
shown below. They contain a CLI example and/or a Web Interface example as appropriate. (The
NetDefendOS CLI Reference Guide documents all CLI commands.)
Example 1. Example Notation
Information about what the example is trying to achieve is found here, sometimes with an explanatory image.
Command-Line Interface
The Command Line Interface example would appear here. It would start with the command prompt followed by
the command:
gw-world:/> somecommand someparameter=somevalue
Web Interface
15

The Web Interface actions for the example are shown here. They are also typically a numbered list showing what
items in the tree-view list at the left of the interface or in the menu bar or in a context menu need to be opened
followed by information about the data items that need to be entered:
1. Go to: Item X > Item Y > Item Z
2. Now enter:
•DataItem1: datavalue1
•DataItem2: datavalue2
Highlighted Content
Sections of text which the reader should pay special attention to are indicated by icons on the left
hand side of the page followed by a short paragraph in italicized text. Such sections are of the
following types with the following purposes:
Note
This indicates some piece of information that is an addition to the preceding text. It
may concern something that is being emphasized, or something that is not obvious or
explicitly stated in the preceding text.
Tip
This indicates a piece of non-critical information that is useful to know in certain
situations but is not essential reading.
Caution
This indicates where the reader should be careful with their actions as an undesirable
situation may result if care is not exercised.
Important
This is an essential point that the reader should read and understand.
Warning
This is essential reading for the user as they should be aware that a serious situation
may result if certain actions are taken or not taken.
Trademarks
Certain names in this publication are the trademarks of their respective owners.
Windows,Windows XP,Windows Vista and Windows 7 are either registered trademarks or
trademarks of Microsoft Corporation in the United States and/or other countries.
Preface
16

Chapter 1. NetDefendOS Overview
This chapter outlines the key features of NetDefendOS.
• Features, page 17
• NetDefendOS Architecture, page 20
• NetDefendOS State Engine Packet Flow, page 24
1.1. Features
D-Link NetDefendOS is the base software engine that drives and controls the range of NetDefend
Firewall hardware products.
NetDefendOS as a Network Security Operating System
Designed as a network security operating system, NetDefendOS features high throughput
performance with high reliability plus super-granular control. In contrast to products built on top of
standard operating systems such as Unix or Microsoft Windows, NetDefendOS offers seamless
integration of all its subsystems, in-depth administrative control of all functionality, as well as a
minimal attack surface which helps to negate the risk from security attacks.
NetDefendOS Objects
From the administrator's perspective the conceptual approach of NetDefendOS is to visualize
operations through a set of logical building blocks or objects. These objects allow the configuration
of NetDefendOS in an almost limitless number of different ways. This granular control allows the
administrator to meet the requirements of the most demanding network security scenarios.
Key Features
NetDefendOS has an extensive feature set. The list below presents the key features of the product:
IP Routing NetDefendOS provides a variety of options for IP routing
including static routing, dynamic routing, as well as multicast
routing capabilities. In addition, NetDefendOS supports
features such as Virtual LANs, Route Monitoring, Proxy ARP
and Transparency. For more information, please see
Chapter 4, Routing.
Firewalling Policies NetDefendOS provides stateful inspection-based firewalling
for a wide range of protocols such as TCP, UDP and ICMP.
The administrator can define detailed firewalling policies
based on source/destination network/interface, protocol,
ports, user credentials, time-of-day and more. Section 3.6, “IP
Rules”, describes how to set up these policies to determine
what traffic is allowed or rejected by NetDefendOS.
Address Translation For functionality as well as security reasons, NetDefendOS
supports policy-based address translation. Dynamic Address
Translation (NAT) as well as Static Address Translation
(SAT) is supported, and resolves most types of address
translation needs. This feature is covered in Chapter 7,
Address Translation.
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VPN NetDefendOS supports a range of Virtual Private Network
(VPN) solutions. Support exists for IPsec, L2TP and PPTP as
well as SSL VPN with security policies definable for
individual VPN connections. This topic is covered in
Chapter 9, VPN.
TLS Termination NetDefendOS supports TLS termination so that the
NetDefend Firewall can act as the end point for connections
by HTTP web-browser clients (this feature is sometimes
called SSL termination). For detailed information, see
Section 6.2.10, “The TLS ALG”.
Anti-Virus Scanning NetDefendOS features integrated anti-virus functionality.
Traffic passing through the NetDefend Firewall can be
subjected to in-depth scanning for viruses, and virus sending
hosts can be black-listed and blocked. For details of this
feature, seeSection 6.4, “Anti-Virus Scanning”.
Intrusion Detection and
Prevention To mitigate application-layer attacks towards vulnerabilities
in services and applications, NetDefendOS provides a
powerful Intrusion Detection and Prevention (IDP) engine.
The IDP engine is policy-based and is able to perform
high-performance scanning and detection of attacks and can
perform blocking and optional black-listing of attacking
hosts. More information about the IDP capabilities of
NetDefendOS can be found in Section 6.5, “Intrusion
Detection and Prevention”.
Note
Full IDP is available on all D-Link NetDefend
product models as a subscription service. On
some models, a simplified IDP subsystem is
provided as standard.
Web Content Filtering NetDefendOS provides various mechanisms for filtering web
content that is deemed inappropriate according to a web usage
policy. With Web Content Filtering (WCF) web content can
be blocked based on category (Dynamic WCF), malicious
objects can be removed from web pages and web sites can be
whitelisted or blacklisted. More information about this topic
can be found in Section 6.3, “Web Content Filtering”.
Traffic Management NetDefendOS provides broad traffic management capabilities
through Traffic Shaping,Threshold Rules (certain models
only) and Server Load Balancing.
Traffic Shaping enables limiting and balancing of bandwidth;
Threshold Rules allow specification of thresholds for sending
alarms and/or limiting network traffic; Server Load Balancing
enables a device running NetDefendOS to distribute network
load to multiple hosts. These features are discussed in detail
in Chapter 10, Traffic Management.
Note
Threshold Rules are only available on certain
D-Link NetDefend product models.
Operations and Maintenance Administrator management of NetDefendOS is possible
through either a Web-based User Interface (the WebUI) or via
a Command Line Interface (the CLI). NetDefendOS also
1.1. Features Chapter 1. NetDefendOS Overview
18

provides detailed event and logging capabilities plus support
for monitoring through SNMP. More detailed information
about this topic can be found in Chapter 2, Management and
Maintenance.
ZoneDefense NetDefendOS can be used to control D-Link switches using
the ZoneDefense feature. This allows NetDefendOS to isolate
portions of a network that contain hosts that are the source of
undesirable network traffic.
Note
NetDefendOS ZoneDefense is only available on
certain D-Link NetDefend product models.
IPv6 IPv6 addresses are supported on interfaces and within
rulesets. This feature is not enabled by default and must be
explicitly enables on an Ethernet interface. More information
about this topic can be found in Section 3.2, “IPv6 Support”.
NetDefendOS Documentation
Reading through the available documentation carefully will ensure getting the most out of the
NetDefendOS product. In addition to this document, the reader should also be aware of the
companion reference guides:
• The CLI Reference Guide which details all NetDefendOS CLI commands.
• The NetDefendOS Log Reference Guide which details all NetDefendOS log event messages.
Together, these documents form the essential reference material for NetDefendOS operation.
1.1. Features Chapter 1. NetDefendOS Overview
19

1.2. NetDefendOS Architecture
1.2.1. State-based Architecture
The NetDefendOS architecture is centered around the concept of state-based connections.
Traditional IP routers or switches commonly inspect all packets and then perform forwarding
decisions based on information found in the packet headers. With this approach, packets are
forwarded without any sense of context which eliminates any possibility to detect and analyze
complex protocols and enforce corresponding security policies.
Stateful Inspection
NetDefendOS employs a technique called stateful inspection which means that it inspects and
forwards traffic on a per-connection basis. NetDefendOS detects when a new connection is being
established, and keeps a small piece of information or state in its state table for the lifetime of that
connection. By doing this, NetDefendOS is able to understand the context of the network traffic
which enables it to perform in-depth traffic scanning, apply bandwidth management and a variety of
other functions.
The stateful inspection approach additionally provides high throughput performance with the added
advantage of a design that is highly scalable. The NetDefendOS subsystem that implements stateful
inspection will sometimes be referred to in documentation as the NetDefendOS state-engine.
1.2.2. NetDefendOS Building Blocks
The basic building blocks in NetDefendOS are interfaces, logical objects and various types of rules
(or rule sets).
Interfaces
Interfaces are the doorways through which network traffic enters or leaves the NetDefend Firewall.
Without interfaces, a NetDefendOS system has no means for receiving or sending traffic.
The following types of interface are supported in NetDefendOS:
•Physical interfaces - These correspond to the actual physical Ethernet interfaces.
•Sub-interfaces - These include VLAN and PPPoE interfaces.
•Tunnel interfaces - Used for receiving and sending traffic through VPN tunnels.
Interface Symmetry
The NetDefendOS interface design is symmetric, meaning that the interfaces of the device are not
fixed as being on the "insecure outside" or "secure inside" of a network topology. The notion of
what is inside and outside is totally for the administrator to define.
Logical Objects
Logical objects can be seen as predefined building blocks for use by the rule sets. The address book,
for instance, contains named objects representing host and network addresses.
Another example of logical objects are services which represent specific protocol and port
combinations. Also important are the Application Layer Gateway (ALG) objects which are used to
define additional parameters on specific protocols such as HTTP, FTP, SMTP and H.323.
1.2. NetDefendOS Architecture Chapter 1. NetDefendOS Overview
20