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Can't telnet any longer to router via port 23

John Cheetley
Level 3
Level 3

Hi Cisco team,

I need to re-connect to cisco ios router to change DHCP and vlan interface details for IP scope address

I have a telnet issue from server 2008 (192.168.0.102) to cisco router hosting CUCM 7.1.2 (192.168.0.12)

Gateway is 192.168.0.1

Am logged in as admin

Telnet is enabled in services.msc. 

Firewall is off for testing purposes.

Error message is 
Connecting To 192.168.0.12...Could not open connection to the host, on port 23:
Connect failed

Troubleshooting.

Have disabled and re-enabled telnet. Have uninstalled/reinstalled

Can tracert and ping OK from 192.168.0.102 to 192.168.0.12 and gateway 192.168.0.1

Can connect OK via CUCM command line as can ping and tracert to the ISP

Done netstat -r , tracert and ping with output attached and netstat -ab

Have uninstalled and re-installed telnet server to no affect

Am open to other questions/suggestions please

1 Accepted Solution

Accepted Solutions

ahmedshoaib
Level 4
Level 4

Hi,

Can you verify is there any access-list is configured on router interface (192.168.0.X) or line vty? If so, then you need to allow your server to access Router via telnet.

Thanks & Best regards.

View solution in original post

7 Replies 7

ahmedshoaib
Level 4
Level 4

Hi,

Can you verify is there any access-list is configured on router interface (192.168.0.X) or line vty? If so, then you need to allow your server to access Router via telnet.

Thanks & Best regards.

Hi ahmedshoaib,

Thanks for your reply.

The only one I have is for..

access-list 10 permit 192.168.2.0 0.0.0.255

Hi,

Is ACL 10 implement on vty line? if so then you need to allow your 192.168.0.102 (Server Address) in your ACL 10 also.

Which will allow your server to access Router via telnet.

access-list 10 permit host 192.168.0.102 (specific server)

OR

access-list 10 permit 192.168.0.0 0.0.0.255 (complete dinner)

Thanks & Best regards.

Thanks ahmedshoaib,

Little bit hard to update this when I can't telnet to the router to do this unfortunately.

Any other ideas please?

Sounds like you've locked yourself out here.  If this is the only reachable interface on the router:

1.  Get in via the console cable (serial, 9600 baud, N-8-1 would be default).

2.  Correct the configuration.

This would be non-disruptive, other than you have to have serial cable attached to the router.

Hi ahmedshoaib,

Thanks for your help. I did another warm boot of server and is working now. I have also now used:

conf t

exec-timeout 0 ...

John,

not sure if your troubleshooting has included reinstalling the Telnet client on the Windows 2008 Server. From the command prompt, type:

pkgmgr /iu:"TelnetClient"

I had a similar issue once and that worked for me. After reinstalling the client, stop and start the Telnet service.

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