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Fortigate SIP ALG / Fortinet SIP ALG

FortiOS has two features that can modify the SIP headers and SDP parameters. The first feature is called the “SIP Session Helper”. If you are experiencing one way audio issues disable this feature first, reboot your IP phone then try making another call. If disabling the session helper does not work, disable the SIP ALG as well.

To disable the sip session helper:

1 Enter the following command to find the sip session helper entry in the session-helper list:

show system session-helper

edit 10
set name sip
set port 5060
set protocol 17

2 Enter the following command to delete session-helper list entry number 10 to disable the sip session helper:

config system session-helper
delete 10

To disable the SIP ALG:

There are typically two VOIP profiles on a factory shipped Fortinet firewall. You may need to disable both profiles to fully stop the ALG.

config voip profile
edit VoIP_Pro_2
config sip
set status disable
end
end

See the Fortigate Technical documentation page for further details.

Fortigate SIP ALG / Fortinet SIP ALG

FortiOS has two features that can modify the SIP headers and SDP parameters. The first feature is called the “SIP Session Helper”. If you are experiencing one way audio issues disable this feature first, reboot your IP phone then try making another call. If disabling the session helper does not work, disable the SIP ALG as well.

To disable the sip session helper:

1 Enter the following command to find the sip session helper entry in the session-helper list:

show system session-helper

edit 10
 set name sip
 set port 5060
 set protocol 17

2 Enter the following command to delete session-helper list entry number 10 to disable the sip session helper:

config system session-helper
 delete 10

To disable the SIP ALG:

There are typically two VOIP profiles on a factory shipped Fortinet firewall. You may need to disable both profiles to fully stop the ALG.

config voip profile
 edit VoIP_Pro_2
 config sip
 set status disable
 end
 end

See the Fortigate Technical documentation page  for further details.

*ALG(Application Layer Gateway)란?

NetScreen에서 V5.0에서 특정한 프로토콜(SIP, FTP, H.323 등)을 지원하는 신규 기능으로 ALG는 특정한 트래픽을 분석하여 NetScreen 방화벽을 통과하여 서비스가 가능하도록 resource 할당, 유동적인 방화벽 정책(ex: dynamic port을 요청하는 경우 편리하게 지원가능)을 설정할 수 있도록 지원할 수 있는 기능으로 Protocol Convert 역할을 할 수 있음, 알려진 포트를 사용하는 경우 및 정책에서 지정하는 경우 ALG기능을 사용할 수 있으며 ALG는 해당 프로토콜의 Payload 내용을 감지 또는 변경할 수 있습니다.