Running passwd with rexec

[Jeff Machols]

Is it possible to run the passwd command with rexec? I am getting pam_chauthok: System error

I am assuming this has something to do with getlogname failing becase rexec doesn't put an entry in utmp. Any ideas?

[Jeff Machols]

also... I am running a trusted system

[G. Vrijhoeven]

Hi,

1. Why do you have .rhosts files on a trusted system?


you can use cryptpw to generate an encrypted passwd sting. copy it in the /etc/passwd file and save it.

this can be done with a simple script.

Hope this will help,

Gideon

[Scott Van Kalken]

With a trusted system you use the Pluggable Authentication Module (pam) as you're aware. You may be able to get around this by specifiying other libraries in /etc/pam_user.conf

You could for example, have a user set up to do the rexec (don't reccommend root) and have the auth details for that user specified in pam_user.conf to allow insertion of users into the password file.

If that makes sense.

man pam.conf for libraries, services and modules used.

man pam_user.conf for configuration of per user pam settings.

The pam_user.conf file will override the default pam.conf (system wide) for users specified in it.

I'm not sure how you'd do this, but I'm 100% sure it's possible.

Scott.

[Steven Gillard_2 · Accepted solution]

I get the same "System Error" when I try to run passwd through rexec, and I don't have a trusted system.

Looking at a syscall trace of the passwd command it appears that things go wrong after it gets a ENXIO (no such device or address) when attempting to open /dev/tty. This is expected since there is no controlling terminal associated with a process started by rexecd.

I guess this means you can't run the passwd command from rexec. You could try telnet as a workaround if you really need to do this:

{
sleep 1
echo
sleep 1
echo
sleep 1
echo "passwd"
sleep 1
echo
sleep 1
echo
sleep 1
echo
sleep 1
echo "logout"
} | telnet

NOTE: this telnet solution breaks with the current telnet patch. I'm told a fix is on its way.

Regards,
Steve