Port 5000 is being used by system

[gio.bitsadze]

Cisco 4331 Router

ip nat inside source static tcp 192.168.200.45 5000 interface GigabitEthernet0/0/0 5000

%Port 5000 is being used by system

any guesses?

[balaji.bandi]

what is the version of code running, i have seen someone reported before has some bug same kind?

[gio.bitsadze]

Maybe it is possible

[balaji.bandi]

there is bug reported and see the workaround posted other post.

[Filip Knezevic]

This is a bug. Apparently you need to create overload rule first, then add static nat rules.

Conditions:
ISR4351 running version 15.4(3)S1
NAT Overload had been configured before the Port Forwarding attempt.
Workaround:
Remove all nat statments and configure static nat before nat overload.

- remove all NAT statements

- save

- reboot

- drop in static NAT statements

- put in PAT/Overload NAT

[gio.bitsadze]

Already tried, don't works

[balaji.bandi]

check this thread may help you :

https://community.cisco.com/t5/switching/quot-nat-port-lt-gt-is-being-used-by-system-quot-on-cisco/td-p/2890534

still, having an issue worth opening the TAC case to assist better.

[Filip Knezevic]

:(

That was the only reference to the issue that I could find :(

[balaji.bandi]

yes, i am afraid, i can not simulate your issue, do not have ISR in hand now..raise TAC to get a quick fix.

[Georg Pauwen]

Hello,

I think you deleted your previous post, not sure if you have seen the last suggestion.

Check if your IOS supports the command below:

ip nat settings interface-overload block port tcp 5000

That would free the port to be used for static NAT. I do think you need a 16.x XE release for the command to be available, not sure about that...