Unable to Telnet.....

Unanswered Question
Jun 6th, 2008


I have two IP's Configured on my Cisco 2800. - Loopback and on Fast Ethernet. Both IP's are pingable across the WAN. And telnet to loopback IP is working fine. However I am unable to telnet to Fast Ethernet IP. The error message while trying to telnet to Fast Ethernet IP is: "Could not open connection to the host, on port 23: Connect failed". I tried to debug telnet on the router. The Debug output for unsuccessful telnet is as follows:


Telnet194: recv SB NAWS 139 24


However for a successful telnet session, the output is:

Telnet195: 1 1 251 1

TCP195: Telnet sent WILL ECHO (1)

Telnet195: 2 2 251 3

TCP195: Telnet sent WILL SUPPRESS-GA (3)

Telnet195: 80000 80000 253 24

TCP195: Telnet sent DO TTY-TYPE (24)

Telnet195: 10000000 10000000 253 31

TCP195: Telnet sent DO WINDOW-SIZE (31)

TCP195: Telnet received DO ECHO (1)

TCP195: Telnet received DO SUPPRESS-GA (3)

TCP195: Telnet received WILL TTY-TYPE (24)

Telnet195: Sent SB 24 1

TCP195: Telnet received WILL WINDOW-SIZE (31)

Telnet195: recv SB NAWS 110 52

Telnet195: recv SB 24 0 ANSI


There are no ACL's or firewalls involved in the picture.


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Overall Rating: 1 (1 ratings)
Richard Burts Fri, 06/06/2008 - 03:43


You have posted this same question on the LAN Switching and Routing forum where I suggested that you post the router config.



Pravin Phadte Fri, 06/06/2008 - 04:59

try to config the int with below and check.

- conf t

- interface Fast Ethernet

- ip tcp adjust-mss 1200

Hope this helps



vatsey.sharad Tue, 06/10/2008 - 01:47


The Interface Config is:

interface FastEthernet0

ip address

ip route-cache flow

ip policy route-map XYZ

speed 100



vatsey.sharad Tue, 06/10/2008 - 02:07

That is to divert traffic from and to specific subnets to the second WAN Link.

However even when i gave a :Permit IP any any" in Route Map's ACL, the telnet session was not established.

Wilson Samuel Tue, 06/10/2008 - 05:10

Hi Sharad,

I'm sure there is some config entry that is making the telnet not possible.

We shall request you to paste the config (you may take out all sensitive info) as that will make it much easier to diagnose.


Wilson Samuel


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