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Can't telnet any longer to router via port 23 once again

John Cheetley
Level 3
Level 3

Evening techs,

Can no longer telnet to router again from windows server 192.168.0.102. Was connected 4 days ago OK no problem

C:\Users\Administrator>telnet 192.168.0.12

Can telnet to switch OK on ip of 192.168.0.2

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

Troubleshooting done

Have disabled and re-enabled telnet via services.msc

Have un-installed/re-installed telnet client/server

Firewall is off.

C:\Users\Administrator>tlntadmn \\thebeast config port=23
The settings were successfully updated.

C:\Users\Administrator>ping 192.168.0.12

Pinging 192.168.0.12 with 32 bytes of data:
Reply from 192.168.0.12: bytes=32 time<1ms TTL=64
Reply from 192.168.0.12: bytes=32 time<1ms TTL=64
Reply from 192.168.0.12: bytes=32 time<1ms TTL=64
Reply from 192.168.0.12: bytes=32 time<1ms TTL=64

Ping statistics for 192.168.0.12:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

C:\Users\Administrator>tracert 192.168.0.12

Tracing route to 192.168.0.12 over a maximum of 30 hops

1 <1 ms <1 ms <1 ms 192.168.0.12

Trace complete.

netstat -a

Active Connections

Proto Local Address Foreign Address State
TCP 0.0.0.0:23 TheBeast:0 LISTENING

Is there a way that we can see what telnet is doing?

47 Replies 47

Hi John,

I checked router configuration and found everything is ok. Please check your server firewall for any block. 

Regards,

Deepak Kumar

www.deepuverma.in

Regards,
Deepak Kumar,
Don't forget to vote and accept the solution if this comment will help you!

Various copies of the config have exec timeout for vty as 35791 (which is a quite long timeout) or as zero (which is no timeout at all). My guess is that telnet sessions are established and then exited but without actually terminating the session on the router. The result is that all available vty are busy and the telnet request is rejected. My suggestion is to configure an exec timeout for all vty that is shorter than 35791 and certainly not zero. You might also evaluate how you are ending the telnet session and see if it is actually terminating the telnet on the router.

HTH

Rick

HTH

Rick

John,

the last time, a warm boot of the server solved the problem...?

Not sure if 'transport input telnet ssh' has been added to the config of your VTY lines...

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