Telnet Server functionality

Hi,

I am trying to understnad by staandard what should be the behaviour of
Telnet Server in below scenario.

1. Telnet server is listening on IP 192.168.11.91 on Telnet port.
2. Client(192.168.11.21- Linux Host) initiates telnet connection to
TelnetServer.
3. Some activity from telnet client transfer and dir etc...
4. Telnet Server IP address(192.168.11.91) goes down (any damn
reason... manually done)
5. At TelnetClient side(192.168.11.21) telnet prompt goes in hang
status.. what you type you can not see it... and after some time having
not received ack of TCP packets sent to Server, it asks for ARP...

6. After some time Telnet Server comes up(192.168.11.91 comes up)
7. TelnetClient gets the ARP reply and now tries to send unacknowledged
TCP packets back (PLEASE NOTE, Those commands were actually not seen
BY USER as prompt was in hang state)... it sends those commands typed
on telnet prompt and get the reply from Server.


Now Is it proper Telnet Client and Server behaviour in this scenario?
If not what could be the correction at Clietn/Server side.



Thanks,
Divakar.

(E-Mail Removed) wrote:
> Hi,
>
> I am trying to understnad by staandard what should be the behaviour of
> Telnet Server in below scenario.
>
> 1. Telnet server is listening on IP 192.168.11.91 on Telnet port.
> 2. Client(192.168.11.21- Linux Host) initiates telnet connection to
> TelnetServer.
> 3. Some activity from telnet client transfer and dir etc...
> 4. Telnet Server IP address(192.168.11.91) goes down (any damn
> reason... manually done)
> 5. At TelnetClient side(192.168.11.21) telnet prompt goes in hang
> status.. what you type you can not see it... and after some time having
> not received ack of TCP packets sent to Server, it asks for ARP...
>
> 6. After some time Telnet Server comes up(192.168.11.91 comes up)
> 7. TelnetClient gets the ARP reply and now tries to send unacknowledged
> TCP packets back (PLEASE NOTE, Those commands were actually not seen
> BY USER as prompt was in hang state)... it sends those commands typed
> on telnet prompt and get the reply from Server.
>
>
> Now Is it proper Telnet Client and Server behaviour in this scenario?
> If not what could be the correction at Clietn/Server side.
>

Telnet is running on top of TCP. What you've seen is proper
TCP behaviour when the connection to the server is temporarily
broken, but the server is not rebooted.

For details, get a book on TCP/IP protocols, e.g.

W. Richard Stevens, TCP/IP Illustrated, Volume 1.

--

Tauno Voipio
tauno voipio (at) iki fi

Thanks Tauno, I got it...