11-11-2015 08:37 PM - edited 03-05-2019 02:43 AM
Hello I was wondering how do I go about opening up a port for a CISCO 1941 router?
I would like to forward port 25 to a certain IP Address on my network from the WAN
I have looked in the routers setup but I can't find any ports or options to setup ports.
Thanks.
11-12-2015 02:26 AM
Hey if you want to forward ports open you use NAT heres and example of static port forward
ip nat inside source static tcp 10.0.1.17 21 146.1.1.44 21 ex
ip nat inside source static tcp 10.0.5.47 80 146.1.1.44 80 ex
ip nat inside source static tcp 10.0.3.82 443 146.1.1.44 443 ex
int g0/0
ip nat inside
int g0/1
descr WAN
ip nat outside
11-12-2015 04:29 PM
Thanks for the reply, is the format
ip nat inside source static tcp ITERNAL IP 21 EXTERANL IP 21 ex
Thanks
11-13-2015 12:23 AM
Yes thats the format
ip nat inside source static <protocol> <inside IP address> <inside port #> <Inside Global IP or Interface> <External Portx>
11-14-2015 06:28 PM
Hello,
Mark's answer is excellent. I am just giving additional info about that command.
That command actually do two functions.
1-When a packet comes from WAN to LAN, router replaces the destination address with the private address you specified in your NAT command.
2-When packet comes from your server going to WAN, router replaces the source address with the public IP which you specified.
So your server is also able to initiate a outgoing session even with private address as well receving incoming session.
Masoud
11-15-2015 05:47 AM
Hello,
Apart from commenst provided by Fellow friedns on this post.
Just have look on the below link for descriptive explanation of port forwarinding.
http://www.cisco.com/c/en/us/support/docs/long-reach-ethernet-lre-digital-subscriber-line-xdsl/asymmetric-digital-subscriber-line-adsl/12905-827spat.html
Hope it Helps..
-GI
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