ZyXEL Communications P-661HNU-FX Manual

P-661HNU Series Support Notes
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All contents copyright © 2010 ZyXEL Communications Corporation.
P-661HNU-Fx
802.11n Wireless ADSL2+ 4-port Security Gateway
Support Notes
Version3.10
Oct 2010

P-661HNU Series Support Notes
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All contents copyright © 2010 ZyXEL Communications Corporation.
FAQ.....................................................................................................................................6
ZLD FAQ.........................................................................................................6
1. What is ZLD?..........................................................................................6
2. What‟s Multilingual Embedded Web Configurator? .........................6
3. How do I update the firmware and configuration file?.....................6
4. What should I do if I forget the system password?..........................6
5. How to use the Reset button?.............................................................6
6. Is it possible to access a server running behind SUA from the
outside Internet? How can I do it?..........................................................7
7. Is there any troubleshooting method on ZLD platform? .................7
Product FAQ ..................................................................................................8
1. How can I manage P-661HNU-Fx?......................................................8
2. What is the default password for Web Configurator? .....................8
3. What‟s the difference between „Common User Account‟ and
„Administrator Account‟? .........................................................................8
4. Will the device work with my Internet connection? .........................8
5. How do I know the P-661HNU-Fx's WAN IP address assigned by
the ISP?.......................................................................................................9
6. What is the micro filter or splitter used for? .....................................9
7. The P-661HNU-Fx supports Bridge and Router mode, what's the
difference between them?........................................................................9
8. How do I know I am using PPPoE?.....................................................9
9. Why does my provider use PPPoE?...................................................9
10. What is NAT? ..................................................................................... 10
11. How NAT works?...............................................................................10
12. What is DDNS? ..................................................................................11
13. When do I need DDNS service? ...................................................... 11
14. What is DDNS wildcard? Does the P-661HNU-Fx support DDNS
wildcard?.................................................................................................. 12
15. What is Traffic Shaping?..................................................................12
16. Why do we perform traffic shaping in the P-661HNU-Fx?........... 12
17. What do the parameters (PCR, SCR, MBS) mean?....................... 12
18. What do the ATM QoS Types (CBR, UBR, VBR-nRT, VBR-RT)
mean? .......................................................................................................13
ADSL FAQ ....................................................................................................14
1. How does ADSL compare to Cable modems?................................ 14
2. What is the expected throughput? ...................................................14
3. What is the microfilter used for? ...................................................... 14
4. How do I know the ADSL line is up? ................................................14
5. How does the P-661HNU-Fx work on a noisy ADSL? .................... 14

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6. Does the VC-based multiplexing perform better than the
LLC-based multiplexing?.......................................................................15
7. How do I know the details of my ADSL line statistics? .................15
8. What are the signaling pins of the ADSL connector?....................15
9. What is triple play? .............................................................................15
Firewall FAQ ................................................................................................17
General......................................................................................................17
1. What is a network firewall? ....................................................17
2. What makes P-661HNU-Fx secure? .....................................17
3. What are the basic types of firewalls?...................................17
4. What kind of firewall is the P-661HNU-Fx?...........................18
5. Why do you need afirewall when your router has NAT built-in?
.....................................................................................................18
6. What is Denials of Service (DoS) attack?..............................18
7. What is Ping of Death attack?................................................19
8. What is Teardrop attack?.......................................................19
9. What is SYN Flood attack? ....................................................19
10. What is LAND attack?..........................................................19
11 What is Brute-force attack?...................................................19
12. What is IP Spoofing attack?.................................................20
13. What are the default firewall rules in P-661HNU-Fx?.........20
Configuration...........................................................................................20
1. How do I configure the firewall?.............................................20
2. How do I prevent others from configuring my firewall?.........20
3. Why can't I configure my P-661HNU-Fx using Web
Configurator/Telnet over WAN?.................................................21
4. Whycan't I upload the firmware and configuration file using
FTP over WAN?..........................................................................22
Wireless FAQ...............................................................................................23
General FAQ............................................................................................. 23
1. What is a Wireless LAN?.....................................................23
2. What are the advantages of Wireless LAN? .....................23
3. What is the disadvantage of Wireless LAN? ....................23
4. Where can you find 802.11 wireless networks?...............24
5. What is an Access Point? ...................................................24
6. Is it possible to use wireless products from a variety of
vendors?....................................................................................24
7. What is Wi-Fi?.......................................................................24
8. What types of devices use the 2.4GHz Band? .................24
9. Does the 802.11 interfere with Bluetooth device?...........25
10. Can radio signals pass through wall?.............................25
11. What are potential factors that may causes interference
among WLAN products?.........................................................25
12. What's the difference between a WLAN and a WWAN? 26

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13. Can I manually swap the wireless module without
damage any hardware? ...........................................................26
14. What wireless security mode does P-661HNU-Fx support?
.....................................................................................................26
15. What Wireless standard does P-661HNU-Fx support? .26
16. Does P-661HNU-Fx support MAC filtering?....................26
17. Does P-661HNU-Fx support auto rate adaption?...........26
Advanced FAQ.........................................................................................27
1. What is Ad Hoc mode?........................................................27
2. What is Infrastructure mode?.............................................27
3. How many Access Points are required in a given area? 27
4. What is Direct-Sequence Spread Spectrum Technology –
(DSSS)?......................................................................................27
5. What is Frequency-hopping Spread Spectrum Technology
–(FHSS)?...................................................................................27
Security FAQ............................................................................................28
1. How do I secure the data across the P-661HNU-Fx Access
Point's radio link?.....................................................................28
2. What is WEP?........................................................................28
3. What is WPA-PSK? ..............................................................29
4. What is the difference between 40-bit and 64-bit WEP?.29
5. What is a WEP key? .............................................................29
6. Will 128-bit WEP communicate with 64-bit WEP? ...........29
7. Can the SSID be encrypted?...............................................29
8. By turning off the broadcast of SSID, can someone still
sniff the SSID? ..........................................................................29
9. What are Insertion Attacks? ...............................................30
10. What is Wireless Sniffer?..................................................30
Application Notes........................................................................................ 31
General Application Notes.....................................................................31
1. Internet Access Using P-661HNU-Fx under Bridge mode....31
2. Internet Access Using P-661HNU-Fx under Routing mode..35
3. Internet Access Using 3G Backup.........................................37
4. SUA Notes ..............................................................................40
5. Using the Dynamic DNS (DDNS)...........................................49
6. File Sharing.............................................................................50
7. QoS.........................................................................................57
8. Using syslog ...........................................................................60
9. Using IP Multicast...................................................................61
Wireless Application Notes....................................................................62
1. Configure a Wireless Client to Ad hoc mode.........................62
2. Setup WEP (Wired Equivalent Privacy).................................66
3. Site Survey..............................................................................70
4. WPS application .....................................................................73

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5. Configure 802.1x and WPA....................................................74
6. The WPS/WLAN Button.........................................................78
Support Tool................................................................................................79
1. Upgrading Firmware via web GUI .....................................................79
2. Backing –up the Configuration ........................................................79
3. Upload Configuration via web GUI ...................................................81
4. Using FTP to Upload the Firmware and Configuration Files ........82
Using Windows command.........................................................................83

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FAQ
ZLD FAQ
1. What is ZLD?
ZLD is ZyXEL Linux Distribution. It is the Linux based platform abbsorted free
and open source software on our routers that delivers network services and
applications. It is designed in a modular fashion so it is easy for developers to
add new features.
2. What‟sMultilingual Embedded Web Configurator?
Multilinggual Embedded Web Configurator means that it can display with 4
kinds of languanges: English, Turkish, German and French. By factory default
it displays with English, and you can change it in Web GUI.
3. How do I update the firmware and configuration file?
You can do this if you access the P-661HNU-Fx as Administrator. You can
upload the firmware and configuration file to Prestige from Web Configurator,
or using FTP or TFTP client software. You CAN NOT upload the firmware and
configuration file via Telnet because the Telnet connection will be dropped
during uploading the firmware. Please do not power off the router right after the
FTP or TFTP uploading is finished, the router will upload the firmware to its
flash at this moment.
Note: There may be firmware that could not be upgraded from Web
Configurator. In this case, ZyXEL will prepare special Upload Software
for you. Please read the firmware release note carefully when you want to
upload a new fireware.
4. What should I do if I forget the system password?
In case you forget the system password, you can erase the current
configuration and restore factory defaults this way:
Use the RESET button on the rear panel of P-661HNU-Fx to reset the router.
After the router is reset, the LAN IP address will be reset to '192.168.1.1', the
common user account will be reset to 'user/1234', the Administrator account
will be reset to „admin/1234‟.
5. How to use the Reset button?
a. Turn your P-661HNU-Fx on. Make sure the POWER led is on (not
blinking)

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b. Press the RESET button for longer than one second and shorter than
five seconds and release it.
c. Press the RESET button for six seconds and then release it. If the
POWER LED begins to blink, the default configuration has been
restored and the P-661HNU-Fx restarts.
6. Is it possible to access a server running behind SUA from the outside
Internet? How can I do it?
Yes, it is possible because P-661HNU-Fx delivers the packet to the local
server by looking up to a SUA server table. Therefore, to make a local server
accessible to the outside users, the port number and the inside IP address of
the server must be configured. (You can configure it in Web Configurator,
Advanced Setup, Network Setting -> NAT -> Port Forwarding.
7. Is there any troubleshooting method on ZLD platform?
You could mirror WAN packet to LAN host
Telnet into the device, triggle command „/var/trafficmirror.sh nas 1 192.168.1.x‟
Note: It is protected by super username & password, „root/1234‟by
factory default.
Make sure your PC which is used to capture WAN packets has been set with a
static ip 192.168.1.x in case the PC will be allocated another IP after DHCP
lease time.

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Product FAQ
1. How can I manage P-661HNU-Fx?
Multilingual Embedded Web GUI for Local and Remote management
Telnet support („root/1234‟Protected ) for remote configuration change
and status monitoring
FTP sever, firmware upgrade and configuration backup and restore are
supported(„admin/1234‟Protected)
2. What is the default password for Web Configurator?
There are two different accounts for P-661HNU-Fx Web Configurator:
Common User Account and Administrator Account.
By factory default the password for the two accounts are:
Common User Account: user/1234
Administrator Account: admin/1234.
You can change the password after you logging in the Web Configurator.
Please record your new password whenever you change it. The system
will lock you out if you have forgotten your password.
3. What‟s the difference between „Common User Account‟and
„Administrator Account‟?
For Common User Account, it can just change the password of common user
but can‟t change the password of Administrator.
For Administrator Account, it can change both Administrator Account‟s
password and Common User Account‟s password.
Moreover, to manage the P-661HNU-Fx via Telnet, you should use another
account „root/1234‟.
4. Will the device work with my Internet connection?
P-661HNU-Fx is designed to be compatible with major ISPs utilize ADSL as a
broadband service. P-661HNU-Fx offers Ethernet ports to connect to your
somputer so the device is placed in the line between the computer and your
ISP. If your ISP supports PPPoE you can also use the device, because PPPoE
is supported in the device.

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5. How do I know the P-661HNU-Fx's WAN IP address assigned by the
ISP?
You can view "- IP Address : x.x.x.x" shown in Web Configurator „Connection
Status -> System Info -> Device Information -> WAN 1 Information‟to check
this IP address.
6. What is the micro filter or splitter used for?
Generally, the voice band uses the lower frequency ranging from 0 to 4KHz,
while ADSL data transmission uses the higher frequency. The micro filter acts
as a low-pass filter for your telephone set to ensure that ADSL transmissions
do not interfere with your voice transmissions. For the details about how to
connect the micro filter please refer to the user's manual.
7. The P-661HNU-Fx supports Bridge and Router mode, what's the
difference between them?
When the ISP limits some specific computers to access Internet, that means
only the traffic to/from these computers will be forwarded and the other will be
filtered. In this case, we use bridge mode which works as an ADSL modem to
connect to the ISP. The ISP will generally give one Internet account and limit
only one computer to access the Internet.
For most Internet users having multiple computers want to share an Internet
account for Internet access, they have to add another Internet sharing device,
like a router. In this case, we use the router mode which works as a general
Router plus an ADSL Modem.
8. How do I know I am using PPPoE?
PPPoE requires a user account to login to the provider's server. If you need to
configure a user name and password on your computer to connect to the ISP
you are probably using PPPoE. If you are simply connected to the Internet
when you turn on your computer, you probably are not. You can also check
your ISP or the information sheet given by the ISP. Please choose PPPoE as
the encapsulation type in the P-661HNU-Fx if the ISP uses PPPoE.
9. Why does my provider use PPPoE?
PPPoE emulates a familiar Dial-Up connection. It allows your ISP to provide
services using their existing network configuration over the broadband
connections. Besides, PPPoE supports a broad range of existing applications

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and service including authentication, accounting, secure access and
configuration management.
10. What is NAT?
The NAT (Network Address Translation-NAT RFC 1631) is the translation of
an Internet Protocol address used within one network to a different IP address
known within another network. One network is designated as the inside
network and the other is the outside. Typically, one company maps its local
inside network addresses to one or more global outsile IP addresses and
“unmaps”the global IP addresses on the incoming packets back into local IP
addresses. The IP addresses for NAT can be either fixed or dynamically
assigned by the ISP. In addition, you can designate servers, e.g., a Web
server and a Telnet server, on your local network and make them accessible to
the outside world. If you do not define any servers, the NAT offers the
additional benefit of firewall protection. In such case, all incoming connections
to your network will be filtered out by the CPE, thus preventing intruders from
probing your network.
For more information on the IP address translation, please refer to RFC 1631,
The IP Network Address Translator (NAT).
11. How NAT works?
If we define the local IP addressed as the Internal Local Addresses (ILA) and
the global IP addresses as the Inside Gloable Address (IGA), see the following
figure. The term „inside‟refers to the set of networks that are subject to
translation. The NAT operates by mapping the ILA to the IGA required for
communication with hosts on other networks. It replaces the original IP source
address (and TCP or UDP source port numbers) and then forwards each
packet to the Internet ISP, thus making them appear as if they came from the
NAT system itself (e.f., the PCE router). The CPE keeps track of the original
addresses and port numbers, so the incoming reply packets can have their
original values restored.

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12. What is DDNS?
The Dynamic DNS service allows you to alias a dynamic IP address to a static
hostname, allowing your computer to be more easily accessed from various
locations on the Internet. To use the service, you must first apply an account
from several free Web servers such as http://www.dyndns.org/.
Without DDNS, we always tell the users to use the WAN IP of the
P-661HNU-Fxto reach our internal server. It is inconvenient for the users if this
IP is dynamic. With DDNS supported by the P-661HNU-Fx, you apply a DNS
name (e.g., www.zyxel.com.tw) for your server (e.g., Web server) from a
DDNS server. The outside users can always access the web server using the
www.zyxel.com.tw regardless of the WAN IP of the P-661HNU-Fx.
When the ISP assigns the P-661HNU-Fx a new IP, the P-661HNU-Fx updates
this IP to DDNS server so that the server can update its IP-to-DNS entry. Once
the IP-to-DNS table in the DDNS server is updated, the DNS name for your
web server (i.e., www.zyxel.com.tw) is still usable.
13. When do I need DDNS service?
When you want your internal server to be accessed by using DNS name rather
than using the dynamic IP address we can use the DDNS service. The DDNS
server allows to alias a dynamic IP address to a static hostname. Whenever
the ISP assigns you a new IP, the P-661HNU-Fx sends this IP to the DDNS
server for its updates.

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14. What is DDNS wildcard? Does the P-661HNU-Fx support DDNS
wildcard?
Some DDNS servers support the wildcard feature which allows the hostname,
*.yourhost.dyndns.org, to be aliased to the same IP address as
yourhost.dyndns.org. This feature is useful when there are multiple servers
inside and you want users to be able to use things such as
www.yourhost.dyndns.org and still reach your hostname.
Yes, the P-661HNU-Fx supports DDNS wildcard that http://www.dyndns.org/
supports. When using wildcard, you simply enter your host.dyndns.org in the
Host field in „Network Setting -> Dynamic DNS‟to configure Dynamic DNS.
15. What is Traffic Shaping?
Traffic Shaping allocates the bandwidth to WAN dynamically and aims at
boosting the efficiency of the bandwidth. If there are serveral VCs in the
P-661HNU-Fx but only one VC activated at one time, the P-661HNU-Fx
allocates all the Bandwidth to the VC and the VC gets full bandwidth. If another
VCs are activated later, the bandwidth is yield to other VCs after ward.
16. Why do we perform traffic shaping in the P-661HNU-Fx?
The P-661HNU-Fx must manage traffic fairly and provide bandwidth allocation
for different sorts of applications, such as voice, video, and data. All
applications have their own natural bit rate. Large data transactions have a
fluctuating natural bit rate. The P-661HNU-Fx is able to support variable traffic
among different virtual connections. Certain traffic may be discarded if the
virtual connection experiences congestion. Traffic shaping defines a set of
actions taken by the P-661HNU-Fx to avoid congestion; traffic shaping takes
measures to adapt to unpredictable fluctuations in traffic flows and other
problems among virtual connections.
17. What do the parameters (PCR, SCR, MBS) mean?
Peak Cell Rate(PCR): The maximum bandwidth allocated to this connection.
The VC connection throughput is limited by PCR.
Sustainable Cell Rate(SCR): The least guaranteed bandwidth of a VC.
When there are multi-VCs on the same line, the VC throughput is guaranteed
by SCR.
Maximum Burst Size(MBS): The amount of cells transmitted through this
VC at the Peak Cell Rate before yielding to other VCs. Total bandwidth of the
line is dedicated to single VC if there is only one VC on the line. However, as
the other VC asking the bandwidth, the MBS defines the maximum number of
cells transmitted via this VC with Peak Cell rate before yielding to other VCs.

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The P-661HNU-Fx holds the parameters for shaping the traffic among its
virtual channels. If you do not need traffic shaping, please set SCR = 0, MBS =
0 and PCR as the maximum value according to the line rate (for example, 2.3
Mbps line rate will result PCR as 5424 cell/sec.)
18. What do the ATM QoS Types (CBR, UBR, VBR-nRT, VBR-RT) mean?
Constant bit rate(CBR): An ATM bandwidth-allocation service that requires
the user to determine a fixed bandwidth requirement at the time the connection
is set up so that the data can be sent in a steady stream. CBR service is often
used when transmitting fixed-rate uncompressed video.
Unspecified bit rate(UBR): An ATM bandwidth-allocation service that does
not guarantee any throughput levels and uses only available bandwidth. UBR
is often used when transmitting data that can tolerate delays, such as e-mail.
Variable bit rate(VBR): An ATM bandwidth-allocation service that allows
users to specify a throughput capacity (i.e., a peak rate) and a sustained rate
but data is not sent evenly. You can select VBR for bursty traffic and
bandwidth sharing with other applications. It contains two subclasses:
Variable bit rate nonreal time (VBR-nRT):
Variable bit rate real time (VBR-RT):

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ADSL FAQ
1. How does ADSL compare to Cable modems?
ADSL provides a dedicated service over a single telephone line; cable
modems offer a dedicated service over a shared media. While cable modems
have greater downstream bandwidth capabilities (up to 24 Mbps), that
bandwidth is shared among all users on a line, and will therefore vary, perhaps
dramatically, as more users in a neighborhood get online at the same time.
Cable modem upstream traffic will in many cases be slower than ADSL, either
because the particular cable modem is inherently slower, or because of rate
reductions caused by contention for upstream bandwidth slots. The big
difference between ADSL and cable modems, however, is the number of lines
available to each. There are no more than 12 million homes passed today that
can support two-way cable modem transmissions, and while the figure also
grows steadily, it will not catch up with telephone lines for many years.
Additionally, many of the older cable networks are not capable of offering a
return channel; consequently, such networks will need significant upgrading
before they can offer high bandwidth services.
2. What is the expected throughput?
In our test, we can get about 1.6Mbps data rate on 15Kft using the 26AWG
loop. The shorter the loop, the better the throughput is.
3. What is the microfilter used for?
Generally, the voice band uses the lower frequency ranging from 0 to 4KHz,
while ADSL data transmission uses the higher frequency. The micro filter acts
as a low-pass filter for your telephone set to ensure that ADSL transmissions
do not interfere with your voice transmissions. For the details about how to
connect the micro filter please refer to the user's manual.
4. How do I know the ADSL line is up?
You can see the DSL LED Green on the P-661HNU-Fx's front panel is on
when the ADSL physical layer is up.
5. How does the P-661HNU-Fx work on a noisy ADSL?
Depending on the line quality, the P-661HNU-Fx uses "Fall Back" and "Fall
Forward" to automatically adjust the date rate.

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6. Does the VC-based multiplexing perform better than the LLC-based
multiplexing?
Though the LLC-based multiplexing can carry multiple protocols over a single
VC, it requires extra header information to identify the protocol being carried
on the virtual circuit (VC). The VC-based multiplexing needs a separate VC for
carrying each protocol but it does not need the extra headers. Therefore, the
VC-based multiplexing is more efficient.
7. How do I know the details of my ADSL line statistics?
You can use the following CI commands to check the ADSL line
statistics.
CI> dsl_cpe_pipe.sh g997lsg 0 1 (upstream)
CI> dsl_cpe_pipe.sh g997lsg 1 1 (downstream)
You can also do it in Web Configurator, Advanced Setup,
Maintenance -> Diagnostic -> DSL Line -> DSL Line Status:
8. What are the signaling pins of the ADSL connector?
The signaling pins on the P-661HNU-Fx's ADSL connector are pin 3 and pin 4.
The middle two pins for a RJ11 cable.
9. What is triple play?
More and more Telco/ISPs are providing three kinds of services (VoIP, Video
and Internet) over one existing ADSL connection.

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The different services (such as video, VoIP and Internet access) require
different Qulity of Service.
The high priority is Voice (VoIP) data.
The Medium priority is Video (IPTV) data.
The low priority is internet access such as ftp etc …
Triple Play is a port-based policy to forward packets from different LAN port to
different PVCs, thus you can configure each PVC separately to assign different
QoS to different application.

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Firewall FAQ
General
1. What is a network firewall?
A firewall is a system or group of systems that enforces an access-control
policy between two networks. It may also be defined as a mechanism used to
protect a trusted network from an untrusted network. The firewall can be
thought of two mechanisms: One to block the traffic, and the other to permit
traffic.
2. What makes P-661HNU-Fx secure?
The P-661HNU-Fx is pre-configured to automatically detect and thwart Denial
of Service (DoS) attacks such as Ping of Death, SYN Flood, LAND attack, IP
Spoofing, etc. It also uses stateful packet inspection to determine if an inbound
connection is allowed through the firewall to the private LAN. The
P-661HNU-Fx supports Network Address Translation (NAT), which translates
the private local addresses to one or multiple public addresses. This adds a
level of security since the clients on the private LAN are invisible to the
Internet.
3. What are the basic types of firewalls?
Conceptually, there are three types of firewalls:
1. Packet Filtering Firewall
2. Application-level Firewall
3. Stateful Inspection Firewall
Packet Filtering Firewalls generally make their decisions based on the header
information in individual packets. These headers information include the
source, destination addresses and ports of the packets.
Application-level Firewalls generally are hosts running proxy servers, which
permit no traffic directly between networks, and which perform logging and
auditing of traffic passing through them. A proxy server is an application
gateway or circuit-level gateway that runs on top of general operating system
such as UNIX or Windows NT. It hides valuable data by requiring users to
communicate with secure systems by mean of a proxy. A key drawback of this
device is performance.

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Stateful Inspection Firewalls restrict access by screening data packets against
defined access rules. They make access control decisions based on IP
address and protocol. They also 'inspect' the session data to assure the
integrity of the connection and to adapt to dynamic protocols. The flexible
nature of Stateful Inspection firewalls generally provides the best speed and
transparency, however, they may lack the granular application level access
control or caching that some proxies support.
4. What kind of firewall is the P-661HNU-Fx?
1. The P-661HNU-Fx's firewall inspects packets contents and IP headers.
It is applicable to all protocols, that understands data in the packet is
intended for other layers, from network layer up to the application layer.
2. The P-661HNU-Fx's firewall performs stateful inspection. It takes into
account the state of connections it handles so that, for example, a
legitimate incoming packet can be matched with the outbound request
for that packet and allowed in. Conversely, an incoming packet
masquerading as a response to a nonexistent outbound request can be
blocked.
3. The P-661HNU-Fx's firewall uses session filtering, i.e., smart rules, that
enhance the filtering process and control the network session rather
than control individual packets in a session.
4. The P-661HNU-Fx's firewall is fast. It uses a hashing function to search
the matched session cache instead of going through every individual
rule for a packet.
5. Why do you need a firewall when your router has NAT built-in?
With the spectacular growth of the Internet and online access, companies that
do business on the Internet face greater security threats. Although NAT restrict
access to particular computers and networks, however, for the other
companies this security may be insufficient, but firewall can maintain session
state. Thus, for greater security, a firewall is considered.
6. What is Denials of Service (DoS) attack?
Denial of Service (DoS) attacks are aimed at devices and networks with a
connection to the Internet. Their goal is not to steal information, but to disable
a device or network so users no longer have access to network resources.
There are four types of DoS attacks:
1. Those that exploits bugs in a TCP/IP implementation such as Ping of
Death and Teardrop.

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2. Those that exploits weaknesses in the TCP/IP specification such as
SYN Flood and LAND Attacks.
3. Brute-force attacks that flood a network with useless data such as
Smurf attack.
4. IP Spoofing
7. What is Ping of Death attack?
Ping of Death uses a 'PING' utility to create an IP packet that exceeds the
maximum 65535 bytes of data allowed by the IP specification. The oversize
packet is then sent to an unsuspecting system. Systems may crash, hang, or
reboot.
8. What is Teardrop attack?
Teardrop attack exploits weakness in the reassemble of the IP packet
fragments. As data is transmitted through a network, IP packets are often
broken up into smaller chunks. Each fragment looks like the original packet
except that it contains an offset field. The Teardrop program creates a series of
IP fragments with overlapping offset fields. When these fragments are
reassembled at the destination, some systems will crash, hang, or reboot.
9. What is SYN Flood attack?
SYN attack floods a targeted system with a series of SYN packets. Each
packet causes the targeted system to issue a SYN-ACK response, While the
targeted system waits for the ACK that follows the SYN-ACK, it queues up all
outstanding SYN-ACK responses on what is known as a backlog queue.
SYN-ACKs are moved off the queue only when an ACK comes back or when
an internal timer (which is set a relatively long intervals) terminates the TCP
three-way handshake. Once the queue is full, the system will ignore all
incoming SYN requests, making the system unavailable for legitimate users.
10. What is LAND attack?
In a LAN attack, hackers flood SYN packets to the network with a spoofed
source IP address of the targeted system. This makes it appear as if the host
computer sent the packets to itself, making the system unavailable while the
target system tries to respond to itself.
11 What is Brute-force attack?
A Brute-force attack, such as 'Smurf' attack, targets a feature in the IP
specification known as directed or subnet broadcasting, to quickly flood the
target network with useless data. A Smurf hacker flood a destination IP

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address of each packet is the broadcast address of the network, the router will
broadcast the ICMP echo request packet to all hosts on the network. If there
are numerous hosts, this will create a large amount of ICMP echo request
packet, the resulting ICMP traffic will not only clog up the 'intermediary'
network, but will also congest the network of the spoofed source IP address,
known as the 'victim' network. This flood of broadcast traffic consumes all
available bandwidth, making communications impossible.
12. What is IP Spoofing attack?
Many DoS attacks also use IP Spoofing as part of their attack. IP Spoofing
may be used to break into systems, to hide the hacker's identity, or to magnify
the effect of the DoS attack. IP Spoofing is a technique used to gain
unauthorized access to computers by tricking a router or firewall into thinking
that the communications are coming from within the trusted network. To
engage in IP Spoofing, a hacker must modify the packet headers so that it
appears that the packets originate from a trusted host and should be allowed
through the router or firewall.
13. What are the default firewall rules in P-661HNU-Fx?
If you enable firewall, that means the firewall will block any unauthorized
accesses to your network.
If you want to stop certain Internet services, you can enable LAN to WAN
Services Blocking and add common services which are pre-configured to
Blocked Services.
Configuration
1. How do I configure the firewall?
You can use the Web Configurator to configure the firewall for P-661HNU-Fx.
By factory default, if you connect your PC to the LAN Interface of
P-661HNU-Fx, you can access Web Configurator via „http://192.168.1.1‟.
2. How do I prevent others from configuring my firewall?
There are several ways to protect others from touching the settings of your
firewall.
1.Change the default Administrator password and Common User password
since it is required when setting up the firewall.