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Cisco Router-Tell which ports are currently open/VOIP??

cmmosman1
cmmosman1 asked
on
Medium Priority
1,229 Views
Last Modified: 2011-04-14
Is their any way to tell on a Cisco router which ports are currently open?  I'm trying to figure out which ports our Siemens VOIP phones are using. Outgoing traffic is being prioritized (LLQ) on the router but all traffic (incoming) originating from the offsite phone system is not so I’d like to be able to tell which ports it’s opening on the offsite phone system router.
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Top Expert 2005

Commented:
1. see the router config - if you not blocking particular ports with access lists - they all open
2. run portscan software - plenty on the web.

Author

Commented:
I guess I wanted to see which ports are in use and not necessarily which are open, sorry.  Is their someway to tell that?
Top Expert 2005

Commented:
If you have NAT in the router - just enter command "show ip nat translations" and you will see all ports wich in use at the moment.

Also, it will be useful to use "show ip port-map" command to see list of port services available...

Author

Commented:
I unfortunetly don't have the router NATed....any other ideas?

Thanks
Top Expert 2005

Commented:
You can set up sniffer to listen on the router inside/outside interfaces, use Ethereal which is free and brilliant: http://www.ethereal.com/
Just connect router and PC with sniffer to the same hub (not switch) and see what applications/ports in use at the moment...

LAN-------!
              !
           hub---router----internet/WAN
              !
Ethereal PC

Commented:
if just the signalling goes trought the router than SIP uses port 5060
but if also RTP and RTCP stream goes trought the router, it is much bigger issue, because the port for the rtp stream is dinamicly asigned, and you canot predict the port for rtp.

regards.

Author

Commented:
Since the traffic doesn't seem to be going over Cisco IOS H.323 ports 16385-3276 I just ended up matching any traffic destin to the ip addreess of the phone.  Thanks for all you help.
Commented:
PAQed with points refunded (500)

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