Telnet issue in HPUX 11.00

[senthil_kumar_2]

Hi All,

I am using HPUX 11.00, and i have configured telnet, rlogin and ftp in /etc/inetd.conf.

All three was working fine.

Some 3 months before i am not able to connect through Telnet by using putty but able to connect by using telnet command available in Windows XP.

Then for past 2 weeks i am not able to connect through Telnet by using telnet command available in Windows XP.

Please find my configuration file:

# vi /etc/inetd.conf

ftp stream tcp nowait root /usr/lbin/ftpd ftpd -l-v-o

telnet stream tcp nowait root /usr/lbin/telnetd telnetd -b/etc/security.banner

login stream tcp nowait root /usr/lbin/rlogind rlogind -B /etc/security.banner
shell stream tcp nowait root /usr/lbin/remshd remshd
exec stream tcp nowait root /usr/lbin/rexecd rexecd

[Tingli · Accepted solution]

Check your syslog.log file, you might find some info there.

[Lijeesh N G_1]

Hi,

telnet stream tcp nowait root /usr/lbin/telnetd telnetd -b/etc/security.banner <<<===

==>
1)Are you getting the banner(/etc/security.banner ) while trying to do the telnet?
2)Is this file /etc/security.banner is exists??

Reagrds,
LIJEESH N G

[OldSchool]

"Some 3 months before i am not able to connect through Telnet by using putty but able to connect by using telnet command available in Windows XP."

Well, did you tell PuTTY to use telnet (as it's default is ssh)?

"Then for past 2 weeks i am not able to connect through Telnet by using telnet command available in Windows XP."

Is there a firewall in the mix somewhere that may be filtering (blocking) port 23 / telnet traffic? What error messages do you get when you try it.

Does telnet from anywhere else to the 11.0 box in question work?

Are the XP box and HPUX on the same subnet or different?

[Jaime Bolanos Rojas.]

senthil,

Whenever you try to connect, what message do you get after usuing the user name and password? Or do you get any prompt at all?

Regards,

Jaime.

[R.K. #]

Hello Senthil,

What is the error message you are getting when trying to telnet?

Use netstat to check that inetd has read inetd.conf and has opened a socket for port 23 (telnet) and this is in LISTEN status.
# netstat -a |grep telnet

Enable inetd -l and check syslog.log to see if any critical error is logged when telnetd starts.

# lsdev
Look for "tels" and "telm" in the third field.

Check the master driver's device file:
# ll /dev/telnetm

Regds..

[Duncan Edmonstone]

I'm with OldSchool on this one - if telnet works, then PuTTY should work when telnet mode is selected

See the attached picture of the PuTTY configuration dialog - you *did* select telnet/port23 didn't you?

HTH

Duncan

[Mel Burslan]

I think, there are no spaces between -b and /etc/security.banner and ther should be. Not 100% sure but it wont hurt to change and restart inetd by

inetd -k
inetd -l

after doint this, please login to this server and run

tail -f /var/adm/syslog/syslog.log

as you try to telnet to it from another server to see if your request is even reaching the server.

[senthil_kumar_2]

Hi All,

1)The file " /etc/security.banner " is available.

2)When trying from windowsXP using the command "telnet servername"

I am getting black screen after some time (may 15secs) the command prompt will be seen.

I am not able to see the banner.

3)When trying from Linux:

I am getting following error.

suse10tst:~ # telnet ad002223 23
Trying 143.242.67.10...
Connected to ad002223.
Escape character is '^]'.
Connection closed by foreign host.



4)When trying from other Unix:

I am getting following error

root@lgsna:/root > telnet ad002223
Trying...
Connected to ad002223.
Escape character is '^]'.
Local flow control off
Connection closed by foreign host.

[R.K. #]

Try doing telnet by using the IP address and not the servername.

[Lijeesh N G_1]

1)what about with Server IP address,
#telnet

2)Remove the "-B /etc/security.banner" from /etc/inetd.conf, restart inetd with #inetd -c and try,

[senthil_kumar_2]

Hi Mel Burslan

As you suggested i checked the log file (syslog).
root@lgapps:/var/adm/syslog > cat syslog.log | grep -i telnet
Aug 19 09:47:36 ad002223 inetd[3743]: telnet/tcp: Connection from emdlagopsmgr (10.250.0.121) at Wed Aug 19 09:47:36 2009
Aug 19 09:47:36 ad002223 inetd[3743]: execv /usr/lbin/telnetd: Permission denied

Then i changed the permission of the file "telnetd"

root@lgapps:/var/adm/syslog > ll /usr/lbin/telnetd
-r--r--r-- 1 bin bin 94208 Mar 27 2002 /usr/lbin/telnetd
root@lgapps:/var/adm/syslog > chmod 544 /usr/lbin/telnetd


Now it is working fine.

[senthil_kumar_2]

I am closing this thread

[Mel Burslan]

did you by any chance log in to this server and check the contents of this /etc/security.banner ?

Since you can not even see the banner, there might be some offending characters, causing your connection to drop. Or you might be running some sort of a software firewall which is not allowing telnet connections and forcing them to drop as they come in.

Without actual data on the server (not only on the client itself) it is hard to say what's happening.

[Duncan Edmonstone]

I think you closed your thread too early...

one would assume that the telnetd executable had its permisions changed for a reason - if I were to hazard a guess I would say as a crude method of enforcing a security policy (e.g. no clear text passwords on the network and by implication no telnet) - someone may have taken the decision to just make telnetd non-executable rather than removing it from inetd.conf or blocking ports via firewalls etc...

So I suspect all you have done here is treat the symptons, rather than determine the root cause - your next task should be to determine *why* the permissions on telnetd were changed - thats not something you can figure out from the box - you'll need to ask all those with root access to this system...

HTH

Duncan