Elegant Solutions to kill telnet/ssh session Post: 302430327

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Operating Systems Solaris Elegant Solutions to kill telnet/ssh session Post 302430327 by boshyd on Thursday 17th of June 2010 09:05:41 AM

06-17-2010

Registered User

Elegant Solutions to kill telnet/ssh session

We have a generic user account "user1" setup on Solaris 8 that is used by an application. I dont want users to telnet/ssh using this account. Instead if they want to gain access, they must su or sudo to this after logging in with their own ID.

My earlier attempts to accomplish this by disabling telnet/ssh for a particular user have gone nowhere, mostly because I dont understand tcp wrappers.

Disable telnet for a particular user

I am looking for more simpler solutions, maybe a script will do this. A script which looks for this PID and kills it. Before killing the session, I would want a message flashed saying do not login with this account, your telnet session will be removed in 10 seconds or so. Ideally, I want this to happen:

User enters correct "user1" credentials and logs in. System flashes messages saying logout and log back with your own account. Telnet/ssh process is killed.

I got the script to kill the telnet session part as below. However, how do I make message flash for those logging in with this account? Also, how do I ensure this script is always running in background? cron every minute will do the trick or is there any other service (daemon?) which always "listens"? How do I set this up?

Code:

PID=`ps -ef |grep ssh |grep user1 | awk '{print $2}'`
for i in $PID; do echo "killing telnet session process with PID = $i"; 
sleep 10;
kill -9 $PID;
done

Any other more elegant solutions you can propose? Thanks for your time.

Last edited by Scott; 06-17-2010 at 11:50 AM.. Reason: Code tags, please...

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LEARN ABOUT OSF1

ssh-keysign

ssh-keysign(1M) 														   ssh-keysign(1M)

NAME

       ssh-keysign - ssh helper program for host-based authentication

SYNOPSIS

       ssh-keysign

       ssh-keysign  is	used  by ssh(1) to access the local host keys and generate the digital signature required during host-based authentication
       with SSH protocol version 2. This signature is of data that includes, among other items, the name of the client host and the  name  of  the
       client user.

       ssh-keysign  is	disabled  by  default and can be enabled only in the global client configuration file /etc/ssh/ssh_config by setting Host-
       basedAuthentication to yes.

       ssh-keysign is not intended to be invoked by the user, but from ssh. See ssh(1) and sshd(1M) for more information about host-based  authen-
       tication.

       /etc/ssh/ssh_config

	   Controls whether ssh-keysign is enabled.

       /etc/ssh/ssh_host_dsa_key
       /etc/ssh/ssh_host_rsa_key

	   These  files  contain the private parts of the host keys used to generate the digital signature. They should be owned by root, readable
	   only by root, and not accessible to others. Because they are readable only by root, ssh-keysign must  be  set-uid  root  if	host-based
	   authentication is used.

       ssh-keysign will not sign host-based authentication data under the following conditions:

	 o  If the HostbasedAuthentication client configuration parameter is not set to yes in /etc/ssh/ssh_config. This setting cannot be overri-
	    den in users' ~/.ssh/ssh_config files.

	 o  If the client hostname and username in /etc/ssh/ssh_config do not match the canonical hostname of  the  client  where  ssh-keysign	is
	    invoked and the name of the user invoking ssh-keysign.

       In  spite of ssh-keysign's restrictions on the contents of the host-based authentication data, there remains the ability of users to use it
       as an avenue for obtaining the client's private host keys. For this reason host-based authentication is turned off by default.

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWsshu			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+

       ssh(1), sshd(1M), ssh_config(4), attributes(5)

AUTHORS

       Markus Friedl, markus@openbsd.org

HISTORY

       ssh-keysign first appeared in Ox 3.2.

								    9 Jun 2004							   ssh-keysign(1M)