Where's the netmask stored on ASA

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May 27th, 2008
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Hi all,


I have a question about the network objects on an ASA running V 8.0(3). After creating an network object with the corresponding netmask in ASDM I cant see it via CLI. Thers just the name without netmask. Where is the netmask stored? How does the ASA deal with this objects and netmasks?


Kind regards and thanks in advance

MB

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Farrukh Haroon Fri, 05/30/2008 - 05:44
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Perhaps its not showing because you are using the default network mask, for example for Class-C addresses you are using /24. like 192.168.1.0/24.


Or another possibility is that you are using a /32 mask, which the firewall is replacing with the 'host' keyword?


Regards


Farrukh

blaesingmarco Fri, 06/06/2008 - 00:29
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Hello Happs.


I think you are right. The Asa knows which mask fits to the IP.

But for example the IP 68.135.32.32 can be configured with /32 /30 /29 /28 mask as a network object in asdm.

But the mask is not shown in the config via cli.


regards,

Marco

Farrukh Haroon Fri, 06/06/2008 - 02:43
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If you configure the 68.135.32.32 address as /8, it should not show as it is a Class A address and this is the default mask for it. /32 mask should show as 'host 68.135.32.32'. But all others should show in the CLI, otherwise how will the ASA differentiate between /28 and /30.

Also please remember ASA uses subnet mask and not wild-card mask.


Can you show the output of:


show run all object-group?


or


show run object-group


Regards


Farrukh



blaesingmarco Fri, 06/06/2008 - 03:40
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Thanks for your reply.

When I configure in the ASDM the network object 62.135.32.32 255.255.255.248 testnet

it is shown in CLI name 62.135.32.32 testnet

No mask anywhere in the config.After creating an network object group and put the network object in this group the netmask is shown in the CLI. But where is it stored before?


regards,

Marco


Farrukh Haroon Fri, 06/06/2008 - 03:57
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Oh I get it now, you are confusing the 'object-group' command with the 'name' command.


The 'name' command does not support any netmask whatsoever, it is just like how u do 'ip host' on the router. However personally I hate to use them, firstly its difficult to troubleshoot and view logs, people are usually doing 'show log | inc 10.20.20.20' and they get nothing :), because they are supposed to do 'show log | include ISA-SERVER'. Similarly to date Cisco MARS also does not support it.


The netmask you configure (in ASDM) will be visible by:


show run object-group


and NOT by


show run name


You just CALL that name in the object-group command (if you don't want in to to type the IP address and make configs more readable).


Have a look at the following:

http://www.cisco.com/en/US/docs/security/asa/asa80/command/reference/no.html#wp1711954


http://www.cisco.com/en/US/docs/security/asa/asa80/command/reference/no.html#wp1714757


Regards


Farrukh



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