Grandstream Networks GXP21 Series User manual

Grandstream Networks, Inc.
GXP IP Phones
Security Guide

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GXP Security Guide
Table of Contents
OVERVIEW.....................................................................................................................3
WEB UI/SSH ACCESS ...................................................................................................4
Web UI Access .....................................................................................................................................4
Web UI Access Protocols .....................................................................................................................4
Admin Login..........................................................................................................................................5
User Management Levels ....................................................................................................................6
SECURITY FOR SIP ACCOUNTS AND CALLS ............................................................7
Protocols and Ports ..............................................................................................................................7
Anonymous/Unsolicited Calls Protection .............................................................................................8
SRTP ..................................................................................................................................................10
SNMP .................................................................................................................................................10
SECURITY FOR GXP SERVICES ................................................................................ 11
Firmware Upgrade and Provisioning ..................................................................................................11
TR-069................................................................................................................................................12
Syslog.................................................................................................................................................14
SECURITY GUIDELINES FOR GXP DEPLOYMENT ..................................................15

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GXP Security Guide
Table of Figures
Figure 1 : Web UI Access Settings................................................................................................................4
Figure 2 : Web UI Login ................................................................................................................................5
Figure 3 : Change Password on First Boot ...................................................................................................5
Figure 4: Change Admin Level Password.....................................................................................................5
Figure 5 : Change User Level password.......................................................................................................6
Figure 6 : Configure TLS as SIP Transport...................................................................................................7
Figure 7 : SIP TLS Settings...........................................................................................................................7
Figure 8 : Additional SIP TLS Settings ..........................................................................................................8
Figure 9 : Anonymous Call Rejection ............................................................................................................8
Figure 10 : Settings to Block Anonymous Call..............................................................................................9
Figure 11 : SRTP Settings...........................................................................................................................10
Figure 12 : SNMP Setting ...........................................................................................................................10
Figure 13 : Upgrade and Provisioning ........................................................................................................11
Figure 14 : TR-069 Connection Settings.....................................................................................................13
Figure 15 : Syslog Protocol .........................................................................................................................14

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GXP Security Guide
OVERVIEW
This document presents a summary of security measures, factors, and configurations that users are
recommended to consider when configuring and deploying our GXP series of IP Phones.
Note: We recommend using the latest firmware for latest security patches.
The following sections are covered in this document:
•Web UI/SSH Access
Web UI access is protected by username/password and login timeout. Three-level user management is
configurable. SSH access is supported for mainly troubleshooting purpose and it is recommended to disable
it in normal usage.
•Security for SIP Accounts and Calls
The SIP accounts use specific port for signaling and media stream transmission. It also offers configurable
options to block anonymous calls and unsolicited calls.
•Security for GXP Services
GXP supports service such as HTTP/HTTPS/TFTP/FTP/FTPS and TR-069 for provisioning. For better
security, we recommend using HTTPS/FTPS with username/password and using password-protected XML
file. We recommend disabling TR-069 (disabled by default) if not used to avoid potential port exposure.
•Deployment Guidelines for GXP
This section introduces protocols and ports used on the GXP and recommendations for routers/firewall
settings.
This document is subject to change without notice.
Reproduction or transmittal of the entire or any part, in any form or by any means, electronic or print, for
any purpose without the express written permission of Grandstream Networks, Inc. is not permitted.

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GXP Security Guide
WEB UI/SSH ACCESS
Web UI Access
The GXP embedded web server responds to HTTP/HTTPS GET/POST requests. Embedded HTML pages
allow users to configure the device through a web browser such as Microsoft IE, Mozilla Firefox, Google
Chrome and etc. With this, administrators can access and configure all available GXP information and
settings. It is critical to understand the security risks involved when placing the IP Phones on public networks
and it’s recommended not to do so.
Web UI Access Protocols
HTTP and HTTPS are supported to access the GXP’s web UI and can be configured under web UI →
Maintenance → Security settings → Security.
To secure transactions and prevent unauthorized access, it is highly recommended to:
1. Use HTTPS instead of HTTP.
2. Avoid using well known port numbers such as 80 and 443.
Figure 1 : Web UI Access Settings
3. The GXP allow access via SSH for advanced troubleshooting purpose. This is usually not needed
unless the administrator or Grandstream support needs it for troubleshooting purpose. SSH access
on the device is enabled by default with port 22 used. It’s recommended to disable it for daily normal
usage. If SSH access needs to be enabled, changing the port to a different port other than the well-
known port 22 is a good practice.

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GXP Security Guide
Admin Login
Username and password are required to log in the GXP’s web UI.
Figure 2 : Web UI Login
The factory default username for administrator level is “admin” and the default password is “admin”.
Changing the default password at first time login is highly recommended.
When accessing the GXP phones for the first time or after factory reset, users will be asked to change the
default administrator password before accessing GXP Web interface.
To change the password for default user "admin", navigate to Web GUI → Maintenance →Web Access
Figure 4: Change Admin Level Password
Figure 3 : Change Password on First Boot

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GXP Security Guide
The password length must be between 6 and 25 characters. Strong password with a combination of
numbers, uppercase letters, lowercase letters, and special characters is always recommended for security
purpose.
User Management Levels
Two user privilege levels are currently supported:
•Admin
•User
User Level
Username
Password
Web Pages Allowed
User Level
user
123
Only Status and Basic Settings
Administrator Level
admin
admin
All pages
NOTES:
➢It is recommended to keep admin login for administrator only. And user should be provided with
user level login only, if web UI access is needed.
➢Change User Level Password upon the first login by following the below steps:
1. Access your GXP web UI by entering its IP address in your favorite browser.
2. Enter your admin password (default: admin).
3. Go to Basic Settings → New User Password and Enter the new password.
4. Confirm the new password.
5. Press “Save” at the bottom of the page to save your new settings.
Figure 5 : Change User Level password

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GXP Security Guide
SECURITY FOR SIP ACCOUNTS AND CALLS
Protocols and Ports
By default, after a factory reset, all the accounts are active. Knowing the default local SIP port (Account1:
5060; Account2 : 5062 … ) users can make direct IP call even if the accounts are not registered to any PBX.
Therefore, it is recommended to disable the unused ports. Under Web GUI → Accounts → Account X →
General Settings → Account Active: “No”
➢Users can also disable Direct IP calls on all ports under Settings → Call Features: Set “Disable
Direct IP Call:” to “Yes”
•SIP transport protocol:
The GXP supports SIP transport protocol “UDP” “TCP” and “TLS”. By default, it’s set to “UDP”. It’s
recommended to use “TLS” so the SIP signaling is encrypted. SIP transport protocol can be configured
per Account under web UI → Accounts → Account X → SIP Settings → Basic Settings. When “TLS”
is used, we recommend using “sips” instead of “sip” for SIP URI scheme to ensure the entire SIP
transaction is secured instead of “best-effort”.
Figure 6 : Configure TLS as SIP Transport
SIP TLS certificate, private key and password can be configured under Maintenance → Security Settings
→ Security page:
Figure 7 : SIP TLS Settings

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GXP Security Guide
When SIP TLS is used, the GXP also offer additional configurations:
- Validate Server Certificates:
This feature allows users to validate server certificates with our trusted list of TLS connections
- Trusted CA Certificates: Uses the certificate for Authentication
Figure 8 : Additional SIP TLS Settings
•Local SIP port when using UDP/TCP:
Starting from 5060 for Account 1, the port numbers increase by 2 for each account. For example, 5062
is the default local SIP port for Account 2.
•Local SIP port when using TLS:
The SIP TLS port is the UDP SIP port plus 1. For example, if Account 1 SIP port is 5060, its TLS port
would be 5061.
Anonymous/Unsolicited Calls Protection
If the user would like to have anonymous calls blocked, please go to GXP’s Web GUI → Account X →
Call Settings and set “Anonymous Call Rejection “to “Yes” : The GXP will then reject all incoming calls
with anonymous caller ID by sending a “486 Busy here” message.
Figure 9 : Anonymous Call Rejection

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GXP Security Guide
•Additional SIP security settings:
under Web GUI →Account X →SIP Settings →Security Settings:
- Accept Incoming SIP from Proxy Only:
Set “Yes” to force the GXP to Check SIP address of the Request URI in the incoming SIP message; if it
doesn't match the SIP server address of the account, the call will be rejected.
Additionally, the GXP has built-in mechanism that detects and stops the spam SIP calls from ringing the
phones. Please see below the settings.
- Validate Incoming SIP Messages:
Set “Yes” to Validate incoming messages by checking caller ID and CSeq headers. If the message does
not include the headers, it will be rejected.
- Check SIP User ID for Incoming INVITE:
Set “Yes” to enable checking the SIP User ID in the Request URI of incoming INVITE; if it doesn't match
the GXP SIP User ID, the call will be rejected. Direct IP calling will also be disabled if checked.
- Authenticate Incoming INVITE:
Set “Yes” to Challenge the incoming INVITE for authentication with “SIP/401 Unauthorized” message
Figure 10 : Settings to Block Anonymous Call

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GXP Security Guide
SRTP
To protect voice communication from eavesdropping, the GXP support SRTP for media traffic using AES
128&256. It is recommended to use SRTP if it’s supported by the SIP server (Or the service provider).
SRTP can be configured under Web GUI → Account X → Audio Settings.
Figure 11 : SRTP Settings
Selects SRTP mode to choose (“No”, “Enabled but not forced”, “Enabled and forced”, or “Optional”).
Default is No. It uses SDP Security Description to exchange key.
SNMP
SNMP protocol is used for Network management. We recommend disabling it if it is not in use. Users can
do that from the GXP’s Web GUI, under Network → SNMP Settings page:
- Set “Enable SNMP:” to “No”
Figure 12 : SNMP Setting

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GXP Security Guide
SECURITY FOR GXP SERVICES
Firmware Upgrade and Provisioning
The GXP IP Phones support downloading configuration file via TFTP, HTTP/HTTPS, FTP/FTPS. Below
figure shows the related options under Web GUI → Maintenance → Upgrade and Provisioning
Figure 13 : Upgrade and Provisioning

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GXP Security Guide
We recommend users to consider the following options for added security when deploying the GXP with
provisioning.
- Upgrade Via: HTTPS:
By default, HTTPS is selected. This is recommended so the traffic is encrypted while travelling through
the network.
- HTTP/HTTPS/FTP/FTPS User Name and Password:
This can be set up as required on the provisioning server when HTTP/HTTPS/FTP/FTPS is used. Only
when the GXP has the correct username and password configured, it can be authenticated by the
Upgrade/provisioning server and the config file can be downloaded.
- Authenticate Config file:
This sets the GXP to authenticate the configuration file before applying it. When set to “Yes”, the
configuration file must include P value P1 with GXP system’s administration password. If it is missed
or does not match the password, the GXP will not apply the config file.
- XML Config File Password:
The GXP XML config file can be encrypted using OpenSSL. When it’s encrypted, the GXP must supply
the correct password in this field so it can decrypt XML configuration file after downloading it. Then the
configuration can be applied. Please note this feature is supported on XML config file instead of the
binary config file. Therefore, it’s recommended to use XML config file format and encrypt it with this
feature.
- Validate Server Certificates: (under Maintenance → Security settings → Security)
This configures whether to validate the server certificate when downloading the firmware/config file. If
set to "Yes", the GXP will download the firmware/config file only from the legitimate server.
TR-069
TR-069 is disabled by default, it’s recommended to disable it if not used.
When TR-069 is enabled under Maintenance → TR-069, and the service is to be used, users can set up
the following:
•ACS URL: Specifies URL of TR-069 Auto Configuration Servers.
•ACS Username/Password: Enters username/Password to authenticate to ACS.
•Periodic Inform Enable: Sends periodic inform packets to ACS.
•Periodic Inform Interval: Sets frequency that the inform packets will be sent out to ACS.
•Connection Request Username/Password: Enters username/Password for ACS to connect to
the GXP.

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GXP Security Guide
•CPE SSL Certificate: Configures the Cert File for the ATA to connect to the ACS via SSL.
•CPE SSL Private Key: Specifies the Cert Key for the ATA to connect to the ACS via SSL
Figure 14 : TR-069 Connection Settings

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GXP Security Guide
Syslog
The GXP supports sending Syslog to a remote syslog server. By default, it’s sent via UDP and we
recommend changing it to “SSL/TLS” so the syslog messages containing device information will be sent
securely over TLS connection.
Figure 15 : Syslog Protocol

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GXP Security Guide
SECURITY GUIDELINES FOR GXP DEPLOYMENT
Often times the GXP are deployed behind NAT. The network administrator can consider following security
guidelines for the GXP to work properly and securely.
•Turn off SIP ALG on the router
On the customer’s router, it’s recommended to turn off SIP ALG (Application Layer Gateway). SIP ALG
is common in many routers intending to prevent some problems caused by router firewalls by inspecting
VoIP packets and modifying it if necessary. Even though SIP ALG intends to prevent issues for VoIP
devices, it can be implemented imperfectly causing problems, especially in some cases SIP ALG
modifies SIP packets improperly which might cause VoIP devices fail to register or establish calls.
•Use TLS and SRTP for SIP calls
On the GXP, it’s recommended to use TLS for SIP transport with “sips” in SIP URL scheme for SIP
signaling encryption and use SRTP for media encryption.
Below the SIP ports and RTPs port used on the GXP if the network administrator needs to create
firewall rules.
➢Under web UI → Account x → SIP Settings → Basic Settings, the feature “Local SIP Port”
defines the local SIP port used to listen and transmit. The default value when using SIP transport
protocol UDP/TCP is 5060 for Account 1, 5062 for Account 2, 5064 for Account 3, 5066 for Account
4… When using TLS as SIP transport protocol the default value is 5061 for Account 1, 5063 for
Account 2, 5065 for Account 3, … The valid range is from 1 to 65535.
➢Under web UI → Settings → General Settings, the feature “Local RTP Port” defines the local RTP
port used to listen and transmit. Local RTP port ranges from 1024 to 65400 and must be even. It is
the base RTP port for channel 0. When configured channel 0 will use this port_value for RTP, and
port_value+1 for RTCP. Channel 1 will use port_value+2 for RTP and so on, until reaching the limit
and then it will be reset to first port_value. The default value is 5004 for RTP and 5005 for RTCP.
For both GXP21XX and GXP16XX series it is possible to select a range for the Local RTP port from 48
to 10000. Default setting is 200.
Note: On the customer’s firewall, it’s recommended to ensure SIP port is opened for the SIP accounts
on the GXP. It’s not necessary to use the default port 5060/5062/… on the firewall. Instead, the network
administrator can consider mapping a different port on the firewall for GXP SIP port 5060 for security
purpose.

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GXP Security Guide
•Use HTTPS for web UI access
GXP Web UI access should be equipped with strong administrator password in additional to using
HTTPS. Also, do not expose the GXP web UI access to public network for normal usage.
•Use HTTPS for firmware downloading and config file downloading
Use HTTPS for firmware downloading and provisioning. Besides that, set up username and password
for the HTTP/HTTPS server to require authentication. It’s also recommended to turn on “Validate Server
Certificates” so the GXP will validate server certificate when downloading the firmware or config file.