Session created by Syn Cookie

rekuhn — Mon, 10 Aug 2020 06:29:43 GMT

Hello,

what process and what is going on if a session (SIP) is created by "Syn Cookie" ?

Is this a valid Session, does this indicate a Problem ?

We configured an App-Override Policy to mitigate Problems between Phone-System and SIP ALG.

We see now all Sessions are created based on Syn Cookies.

René

Re: Session created by Syn Cookie

reaper — Thu, 13 Aug 2020 07:37:27 GMT

Syn cookies are part of zone protection(not app override)

It requires the client sending the original syn to complete a little "challenge" before the firewall accepts the connection as a valid session

The session is not created "by" the syn cookies, the syn cookie is an added tcp check to prevent syn floods

In regards to sip issues, you can try disabling the ALG via the application (objects > applications) before fiddling with app override

Hope this helps