topic Re: Restict number of telnet sessions in Operating System - HP-UX

Restict number of telnet sessions

KapilRaj — Wed, 07 Apr 2004 04:10:36 GMT

Can I do this ?.

My telnetd service should refuce conenctions after it has reached a number (say 100)

Regds,

Kaps

Re: Restict number of telnet sessions

Mark Grant — Wed, 07 Apr 2004 04:17:25 GMT

You could try and install xinetd instead of inetd but this will probably cause you a few issues.

Otherwise, you could script it in /etc/profile. Something like

[ `ps -ef | grep -v grep | grep telnetd | wc -l` -gt 100 ] && exit

Re: Restict number of telnet sessions

Radhakrishnan Venkatara — Wed, 07 Apr 2004 04:38:42 GMT

kaps,

you can do that.Once i faced the problem after 70 users i am not able to getting telnet connection.So I had to increase the some kernel parameters such as NPTY NSTRPTY and created the device files.I dunno whether the vice-versa will work.
I never tried that.

Regds

Radhakrishnan

Re: Restict number of telnet sessions

Mark Grant — Wed, 07 Apr 2004 04:44:00 GMT

trouble with that one Radhakrishnan is that it would not just restrict telnet. You wouldn't be able to do all sorts of other networking type connections or even have many users with several xterms open.

Re: Restict number of telnet sessions

KapilRaj — Wed, 07 Apr 2004 05:09:09 GMT

This is not really what i want. I want telnetd to reject anything after the 100th telnet connection onto it.

Regds,

Kaps

Re: Restict number of telnet sessions

Mark Grant — Wed, 07 Apr 2004 05:23:09 GMT

I think xinetd is your only option here then. xinetd is a replacement for inetd but it does allow you to specifiy the number of instances of a service.

They don't have it at the porting center but it does compile on hpux.

Re: Restict number of telnet sessions

T G Manikandan — Wed, 07 Apr 2004 06:03:45 GMT

The thing would be to restrict the number with the kernel parameter nstrtel.

If this is set to 100 and there are 100 telnet connections open,then it would reject new connections.

Re: Restict number of telnet sessions

Tim Sanko — Wed, 07 Apr 2004 07:17:06 GMT

All Hail the pharaoh!! he has it right.

Re: Restict number of telnet sessions

Bill Hassell — Wed, 07 Apr 2004 07:25:22 GMT

Depending on how the users make their connection (Xwindows makes it complicated) and the version of HP-UX you are using, just set the 3 kernel parameters: npty, nstrtel and nstrpty all equal to 100. As mentioned, this can affect other services, so you may be better off just counting logins in /etc/profile. Put something like this at the beginning on /etc/profile:

QTY=$(who | wc -l)
if [ $QTY -gt 100 -a $(id -u) -gt 0 ]
then
echo "\n\nSorry, no more connections allowed\n"
sleep 3
exit
fi

The above code is simpler than changing the kernel parameters and will not affect other service connections. Note that this counts every session even if the same user has logged in several times.