Cisco Systems Why does the crypto key show in "show run" on some switches and not others?

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Why does the crypto key show in "show run" on some switches and not others? ttripp 02-04-10
Posted by ttripp on February 4, 2010, 10:12 am
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I'm configuring eight identical Cisco 2960 switches running 12.2(44)
SE6. I'm puzzled by the following behavior:

I am running the "crypto key generate" command on all these switches.
However, on those switches where I've turned on port security using
the "switchport port-security" command, the crypto key no longer
appears when I do a "show run" (they do appear when I do a "show
crypto key mypub rsa", so I know they're there).

On switches where I don't turn on port security, the key shows up in
the config file when I do a "show run".

This is not really a problem in my environment, but is there some
logical reason for this behavior? Or is it just a bug/feature?

Thanks.

Posted by ttripp on February 4, 2010, 11:30 am
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> I'm configuring eight identical Cisco 2960 switches running 12.2(44)
> SE6. =A0I'm puzzled by the following behavior:
>
> I am running the "crypto key generate" command on all these switches.
> However, on those switches where I've turned on port security using
> the "switchport port-security" command, the crypto key no longer
> appears when I do a "show run" =A0(they do appear when I do a "show
> crypto key mypub rsa", so I know they're there).
>
> On switches where I don't turn on port security, the key shows up in
> the config file when I do a "show run".
>
> This is not really a problem in my environment, but is there some
> logical reason for this behavior? =A0Or is it just a bug/feature?
>
> Thanks.

And now I have to take it back. One of the switches shows the crypto
key when I do a "show run", even with port-security enabled on an
interface.

Still wonder what causes this behavior. Is there any way to have the
crypto key ALWAYS show up in "show run"? Or, for that matter, for it
to NEVER show up?


Posted by Phil Harrison on February 10, 2010, 11:43 am
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>
> And now I have to take it back. One of the switches shows the crypto
> key when I do a "show run", even with port-security enabled on an
> interface.
>
> Still wonder what causes this behavior. Is there any way to have the
> crypto key ALWAYS show up in "show run"? Or, for that matter, for it
> to NEVER show up?

Are you sure it's the crypto *keys* shown in running config and not a
PKI cert (if you enabled 'ip http secure-server' for example). The
local RSA keypair should only be stored in private-config not
running/startup.

/Phil


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