How to configure a firewall for a SX20 registered on a VCS Expressway

[Artemisio Stellato]

Hi all,

As you can see in the picture, I have a classic situation. Everything is working properly.

Now customer needs to use a cisco SX20 in a branch office.

The Cisco ASA 5540 firewall is currently configured as follows:

1. static (inside, outside) 213.42.140.136 (public ip) 10209252166 (internal ip)
2. access-list extended permit ip host 87.241.12.76 OUTSIDE_access_in (VCS Expressway IP) host 213.42.140.136

I have done many tests:

• SX20 H.323 configuration whit Nat On, Off and Auto

In all cases the system is recorded correctly, but the call signaling does not occur.

• If instead of using my own system with a public IP it works fine.

Can anyone help me how to properly configure the firewall?

thanks in advance

[Michael Boscia]

What does the ASDM on the firewall say in terms of logging of blocked traffic when it doesn't work?

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[Michael Boscia]

What does the ASDM on the firewall say in terms of logging of blocked traffic when it doesn't work?

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[Artemisio Stellato]

The firewall manager, says that there are no packets dropped.

thanks for the quick response

[Martin Koch · Accepted solution]

Check on the asa that threre is no fixup / inspection enabeld for sip, h323 and skinny.

You find a doc regards voip and ASA here:

http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a008081042c.shtml

[Michael Boscia]

What log level are you looking at?

Does it show the packets getting through?

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[Artemisio Stellato]

Thanks Martin

Following the guide  that you suggested I configured the firewall and now everything is working properly.

Best Regards