SIP traffic pass over firewall even if i set a deny rule

BogdanVM

Hello,

I have a ZyXEL USG 2000 software version: 3.30(AQW.7)

Behind i have a sip server (asterisk) and i wonder how it is possible for sip traffic to pass the firewall regardless of the blocking rules I set on the router.

Does this router have a special and invisible rule in the firewall regarding sip traffic?

If i block the sip server(linux ip extern) from zyxel router firewall i can't connect to any service to that linux (http,ssh,..), but the phones can connect to the sip server…i don t know why

If i allow sip server (linux) from router firewall everything is working (ssh, http,sip,…)

And the firewall rule is simple…just the ip address (not http service or ssh service)

10x

Peter2

sip ALG ?