Session created by Syn Cookie

Showing results for 
Search instead for 
Did you mean: 

Session created by Syn Cookie

L2 Linker



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.





Cyber Elite
Cyber Elite

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



Tom Piens
Like what you see?

Show your appreciation!

Click Like if a post is helpful to you or if you just want to show your support.

Click Accept as Solution to acknowledge that the answer to your question has been provided.

The button appears next to the replies on topics you’ve started. The member who gave the solution and all future visitors to this topic will appreciate it!

These simple actions take just seconds of your time, but go a long way in showing appreciation for community members and the LIVEcommunity as a whole!

The LIVEcommunity thanks you for your participation!