Re: Telnet

[mukund <betacomp@xxxxxxxxxxxxxxxx>]

"Mr.Arun Kumar Bairiganjan" wrote:
> 
> Yes. DNS is ok , inetd is running and telnet localhost is working also. But
> telnet from a pc is slow.
> 
> I have tried with RH 5.2 from PCQ CD and it is fine. So for the time being I
> have installed RHL 5.2.
> 
> Another problem. The Linux machine is in a Lab. where students work. I want to
> disable Ctrl - Alt - Del  rebooting.  Any suggestions. I need only root can
>

Lots of people are confusing DNS.
DNS is domain name server. It is a service offered by the server. If you
click a url or telnet to a machine abc.xyz.com, the client machine makes
a dns request to server to get the ip address of abc.xyz.com. Then the
client sends a tcp packet (telnet / http /ftp etc ) to the ip address.
The tcp packet for any service requires an ip address, it can not be
sent to a name. 
The /etc/host file is used by the server to find ip address of client
machine on network. Now let us consider three scenario.
1. Server to client telnet request - The server searches /etc/host to
find clients ip address, if it is not found then makes dns request if
dns is running. other wise reports that host not found. If ip address is
found  then server  sends a tcp (telnet) request to client with ip
address, and telnet connection is established.  
2. Client to server telnet request- This much simple as server already
has a /etc/host file which has ip address of the server. So connection
is established. But /etc/host file must reflect the correct ip address
of server.
3. Client1 to client2 telnet request- Now here the client1 makes a dns
request to server and gets the ip address of client2 and then sends a
tcp telnet request packet to client2. The dns must be running and
properly configured in this case.

Finally please remember dns is only for domain name to ip address
conversion and if you use ip address then dns is not required.
I hope this helps. 

To disable ctrl+alt+del comment out the relevant line in /etc/initab.

Best Wishes.
- -mukund
http://members.theglobe.com/betacomp/default.html
http://members.xoom.com/BETACOMP/index1.htm



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