ASA 5505 static nat error message

[CHUN FAI LAW]

i would like to port forward an port 4500 on the outside interface to inside host but it shows the error message below.

But if i add for port ftp and tftp without any problem.

[ERROR] nat (inside,outside) 6 source static aruba interface service Aruba-4500 Aruba-4500

NAT unable to reserve ports.

[Marvin Rhoads]

Do you have remote access or site-site VPN also setup and enabled on the outside interface?

If so, port 4500 is used by IPsec so I suspect it is reserved in the appliance.

[CHUN FAI LAW]

yes, we have site to site vpn config on the asa!!

may be this is the reason we can't enable this port on outside interface!!

[Marvin Rhoads]

Yes. Enabling IPsec on the outside interface "siliently" reserved that port.