ZyXEL Communications ZyWall USG20-VPN, User Manual

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Chapter 14 ALG
USG20(W)-VPN Series User’s Guide
271
The following table describes the labels in this screen.
Table 108
Configuration > Network > ALG
LABEL DESCRIPTION
Enable SIP ALG Turn on the SIP ALG to detect SIP traffic and help build SIP sessions through the
USG’s NAT.
Enable SIP
Transformations Select this to have the USG modify IP addresses and port numbers embedded in
the SIP data payload.
You do not need to use this if you have a SIP device or server that will modify IP
addresses and port numbers embedded in the SIP data payload.
Enable Configure SIP
Inactivity Timeout Select this option to have the USG apply SIP media and signaling inactivity time out
limits.
SIP Media Inactivity
Timeout Use this field to set how many seconds (1~86400) the USG will allow a SIP session
to remain idle (without voice traffic) before dropping it.
If no voice packets go through the SIP ALG before the timeout period expires, the
USG deletes the audio session. You cannot hear anything and you will need to make
a new call to continue your conversation.
SIP Signaling Inactivity
Timeout Most SIP clients have an “expire” mechanism indicating the lifetime of signaling
sessions. The SIP user agent sends registration packets to the SIP server
periodically and keeps the session alive in the USG.
If the SIP client does not have this mechanism and makes no calls during the USG
SIP timeout, the USG deletes the signaling session after the timeout period. Enter
the SIP signaling session timeout value (1~86400).
Restrict Peer to Peer
Signaling Connection A signaling connection is used to set up the SIP connection.
Enable this if you want signaling connections to only arrive from the IP address(es)
you registered with. Signaling connections from other IP addresses will be dropped.
Restrict Peer to Peer
Media Connection A media connection is the audio transfer in a SIP connection.
Enable this if you want media connections to only arrive from the IP address(es)
you registered with. Media connections from other IP addresses will be dropped.
SIP Signaling Port If you are using a custom UDP port number (not 5060) for SIP traffic, enter it here.
Use the
Add icon to add fields if you are also using SIP on additional UDP port
numbers.
Additional SIP Signaling
Port (UDP) for
Transformations If you are also using SIP on an additional UDP port number, enter it here.
Enable H.323 ALG Turn on the H.323 ALG to detect H.323 traffic (used for audio communications) and
help build H.323 sessions through the USG’s NAT.
Enable H.323
Transformations Select this to have the USG modify IP addresses and port numbers embedded in
the H.323 data payload.
You do not need to use this if you have a H.323 device or server that will modify IP
addresses and port numbers embedded in the H.323 data payload.
H.323 Signaling Port If you are using a custom TCP port number (not 1720) for H.323 traffic, enter it
here.
Additional H.323
Signaling Port for
Transformations If you are also using H.323 on an additional TCP port number, enter it here.
Enable FTP ALG Turn on the FTP ALG to detect FTP (File Transfer Program) traffic and help build FTP
sessions through the USG’s NAT.