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Unable to reserve port:443 ASA 8.4 5505

Hi guys,

The issue : I cannot reserve 443 nat'd to my interface  as below.  I get the error ' unable to reserve port'

object network EDM_GMalic_RDP

nat (inside,outside) static interface service tcp 443 443

This makes sense since ASDM is running by default on this port so I change it to 444.

http server enable 444

Still get the error.

So I disable http # no http server enable  and try it, same error.

Show asp table socket shows a DTLS connection on the socket , is this anyconnect reserving the port?  What can I do to get this to work?

Protocol  Socket    Local Address               Foreign Address         State

SSL       00015baf  20x.2xx.8x.x3x:443*               LISTEN

DTLS      0002871f  20x.2xx.8x.x3x:443*               LISTEN

Thanks a bunch,


Super Bronze

Unable to reserve port:443 ASA 8.4 5505


I think you will have to use non default port for some of the services to be able to use them all at the same time.

ASDM naturally is not a big deal as its only for the firewall admins.

AnyConnect is a bit more tricky as you probably have many users and its a slight inconvinience to define the port also.

But I would imagine the worst situation would be if you had to change the internal servers public/mapped port to something else than TCP/443

I would suggest changing the AnyConnect port to something else also and then trying again.

I think you need to disable the "webvpn" on the interface where its active and then change the port and re-enable "webvpn" for the interfaces needed.

The actual port configuration to my understanding is done under



The interfaces for which this type of VPN is enabled are also configured under the "webvpn"

Issue the following command to see the settings

show run webvpn

Hope this helps

Please do remember to mark a reply as the correct answer if it answered your question.

- Jouni

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