telnet hang

[Steve_3]

when i try telnet to a node.

Trying....
connected to machine.
Escape character is '^]'

It hangs here for about 1 minute before I get a login prompt.

Any reason why?

Thanks.
steve

[James R. Ferguson]

Steve:

My experience suggests that the delay you are seeing is due to "reverse-name-lookup". Making sure that your device's name is represented in the DNS tables of the DNS server will eliminate the (timeout) delay.

Reverse lookup is the process by which a server receiving a request for service from a remote machine ascertains whether the identity claimed by the machine is in fact its true one. The process goes like this:

1. The request arrives in a packet with an IP address indicating the point of origin.
2. The server queries name service on the net to find out what host name is associated with that IP address.
3. The server then queries name service to find out what IP address is associated with that host-name.
4. If this last request fails to find an IP address, or finds one that doesn't match the original, the request for service is rejected.

For an good description of reverse name lookup, see:

http://www.helpdesk.umd.edu/comm/ethernet/revlook.shtml

...JRF...

[Rick Garland]

Are you able to resolve the node both forward and backwards? The telnet service is one that uses DNS to resolve the host name. Use nslookup to ensure you are resolving.