Telnet

[Scott McDade]

Hello all:

I just set up a RH 4 Linux WS machine. It is up and running without a problem. Very easy to setup. But now I have some people who are trying to telnet into it and are having problem. I can telnet and fto from it but they can't seem to get in. I am trying to avoid using SSH and/or VNC if possible as I would like to limit traffic to this machine. I have made sure the xinetd service is running by using the ps -ef |grep xinetd and I have changed the boot options to make sure it came up automatically via chkconfig. What else should I do?

[Ivan Krastev]

For securing your WS see this guide from RedHat - http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/security-guide/


regards,
ivan

[Alexander Chuzhoy · Accepted solution]

Although telnet is a part of xinetd, to enable it you have to run chkconfig for the telnet service itself:

chkconfig telnet on

[harry_7]

Hi All,

Same here. My telnet sessions are keep disconnecting after some time (minutes). Still I am not able to iolsate the issue. If I am connecting to same server VIA VPN. Then no issue. The sessions remains active.

Regards.

Harry.

[Bill Thorsteinson]

Check hosts.allow. telnet should be running
with tcpwrappers enabled.
It may also be a problem with reverse lookups.

SSH provides better abilities to manage
traffic than telnet. However, you won't be
able to snoop passwords. Tightest SSH security
would be to disable passwords and required
known SSH keys. These can be limited to
particular addresses if desired.

[Al Licause]

Lets get back to your initial problem statement. You said you can telnet in but others cannot. This would inidicate that telnet is setup for incoming connections.

What we don't know is which account are you able to telnet in on...root, non-root, or what ?

Which accounts can't telnet in ?
How do those accounts differ from the account to which you can telnet ?

Can you please list your /etc/xinetd.d/telnet file.

What is the error or response that is seen when telnet fails to allow someone access ?

Are you seeing any errors or entries in anything in the /var/log area.....perhaps the messages or the secure file ?

In terms of lost connections, this is often due to poor communications lines...i.e. you may be having problems with the network connection. By default there is no watchdog timer in linux to disconnect sessions after a certain time period. Again look in the log files and see if anything shows up. Check network interfaces for any possible errors.

[Alpha977]

Hello!

I have the same problem with SSH connection.
I have solved using an iptables rule.

If don't know use iptabels, you can use the "Webmin" interface. (www.webmin.com)
Is a tool free and opensource for manage the machine via web.
It also give possibility to configure iptables with graphical interface via web, to limit the connection over your machine.