Checking if Port is Open on 3845 router

Unanswered Question
Aug 15th, 2007

is there a command that i can do on this router to see if a particular port is open? We have a PPP connection and just want to make sure that a particular application that we use at a remote location is able to come in thru a particular port.

But the other thing is that I assume that if it is PPP connection, that all ports are open. Am I right or am I right? Thanks for the help.

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Jon Marshall Thu, 08/16/2007 - 04:37


Do you mean a port opened that allows traffic through the router ?

If so then unless you have an access-list applied to an interface that denies certain ports by default a router will allow all traffic through so the easiest way is to do a "sh run" and under the interface statements check if there is an

"ip access-group "no/name" in or out

If there is then you need to look at the corresponding access-list so for example

interface fa0/0

ip address

ip access-group 101 in

If you found this you would then do

"sh ip access-list 101" to view the access-lists.




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