Disabling SIP-ALG on FortiOS

On FortiOS sip traffic is picked up by a session helper and processed through sip-alg. To disable sip-alg start by finding and removing the sip session-helper. This will cause sip traffic to be treated as regular traffic. We will also disable nat trace and voip profiles to be sure sip-alg is completely bypassed. This was performed on a Fortigate 60F with firmware version 7.0.15.

Disabling SIP-ALG on FortiOS

#### Delete sip session helper

fortigate # config system session-helper
fortigate (session-helper) # show
config system session-helper
…
    edit 13
        set name sip
        set protocol 17
        set port 5060
    next
…
fortigate (session-helper) # delete 13
fortigate (session-helper) # end

#### Disable sip-nat-trace

fortigate # config  system settings
fortigate (settings) # set sip-nat-trace disable
fortigate (settings) # end

#### Disable default and strict voip profiles

fortigate # config  voip profile
fortigate (profile) # edit default
fortigate (default) # config sip
fortigate (sip) # set status disable
fortigate (sip) # set rtp disable
fortigate (sip) # end
fortigate (profile) # end
fortigate # config  voip profile
fortigate (profile) # edit strict
fortigate (strict) # config  sip
fortigate (sip) # set status disable
fortigate (sip) # set rtp disable
fortigate (sip) # end