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Forum Discussion

themyth_317517's avatar
themyth_317517
Icon for Nimbostratus rankNimbostratus
May 19, 2017

Port 1720 open on F5 public virtual server

Hi guy, My virtual server pulib to Internet via F5 and just open port http/80, https/443, but when i try to telnet port 1720 to Public IP of virtual server, it connect [telnet IP 1720], its working, ...
ASM Advanced WAF
security
MvdG's avatar
MvdG
Icon for Cirrus rankCirrus
May 22, 2017

Hi,

 

Is there a Check Point firewall between the internet and the F5, and is port 1720 (H323) used in the rule base as a custom service?

 

If have seen this kind of behavior with on of our customers. A telnet on port 1720 is accepted by the Check Point because Check Point wants to inspect the H323 traffic. Even if it is a custom service on the same port-number.

 

If there is a NAT rule, it seems like the F5 is accepting the connection, but in fact it is the Check Point.

 

Hope this helps.

 

Martijn.