question about /bin/false usage

slacknewbie2 · 02-11-2006, 07:45 AM

I am having a problem on my Slackware 10.2 system where system users who have no home directory get root access. The displayed message is: No directory, logging in with HOME=/. I also see this: /dev/pts/2: Operation not permitted. I seemed to have solved the second one by copying the /etc/passwd line for these users from a FC4 machine that I have. When I su - to these users though, I get put in the root directory as root which is not good. In this instance, it is the named user. Can someone explain the /etc/passwd file entry to me in detail so that I can figure this out?

Dave

uselpa · 02-11-2006, 08:43 AM

Try `man 5 passwd`.
You could also post your /etc/passwd here, so we could help you figure out.
What exactly do you call "root access"? $HOME=/root? Or really root access rights?

slacknewbie2 · 02-11-2006, 11:21 AM

Using the following line:

nobody:x:99:99:::bin/false

if I su - nobody

I am put into the / directory as root.

This line which is based on the one from my FC4 box:

nobody:x:99:99:Nobody:/:/bin/false

gives a different result if I try to su - nobody. With this line, nothing happens. I believe that is the desired result.

Thanks,
Dave

uselpa · 02-11-2006, 12:16 PM

In /etc/passwd fields are separated by a colon (":").

The first 4 lines are the same (account,password,UID,GID).
The 5th field (GECOS) is optional and ignored.

The 6th field is the user's home directory. In your first case it is empty, which is why you get the message "No directory, logging in with HOME=/.". In the second case it is "/" so there's no message then. But in both cases the HOME dir becomes /.

The 7th field is the program run at login, normally the shell. In both cases it is /bin/false, although I am unsure if the first is correct as the leading "/" is missing. Try adding it.

For information, this is my /etc/passwd on a Slackware 10.2 system:

Code:

root:x:0:0::/root:/bin/bash
bin:x:1:1:bin:/bin:
daemon:x:2:2:daemon:/sbin:
adm:x:3:4:adm:/var/log:
lp:x:4:7:lp:/var/spool/lpd:
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/:
news:x:9:13:news:/usr/lib/news:
uucp:x:10:14:uucp:/var/spool/uucppublic:
operator:x:11:0:operator:/root:/bin/bash
games:x:12:100:games:/usr/games:
ftp:x:14:50::/home/ftp:
smmsp:x:25:25:smmsp:/var/spool/clientmqueue:
mysql:x:27:27:MySQL:/var/lib/mysql:/bin/bash
rpc:x:32:32:RPC portmap user:/:/bin/false
sshd:x:33:33:sshd:/:
gdm:x:42:42:GDM:/var/state/gdm:/bin/bash
pop:x:90:90:POP:/:
nobody:x:99:99:nobody:/:
pu:x:1000:1000:,,,:/home/pu:/bin/bash
sy:x:1001:100:,,,:/home/sy:/bin/bash
clamav:x:1004:1004::/home/clamav:

slacknewbie2 · 02-15-2006, 10:25 AM

Thanks. That helped.

Dave