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Old 07-17-2008, 05:14 PM   #1
techemically
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cannot set to dev/null


I get this when trying to run this command: desktop:~$ grep nobody /etc/passwd
nobody:x:65534:65534:nobody:/nonexistent:/bin/sh
this "nobody" just popped up one day under my normal profile name and i cannot set it to /dev/null. I get permission denied.
 
Old 07-17-2008, 07:42 PM   #2
stress_junkie
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You are seeing this error because you don't have permission to edit the /etc/passwd file. Try changing to the root account or invoke an editor using sudo.

BUT ... the nobody account is useful. It is a standard account used to perform tasks that don't require any privileges or normal user account status. The updatedb utility is usually run in a cron job under the nobody account. That way it does not update the locate database with user files unless the "others" group can see those files.
 
Old 07-17-2008, 07:46 PM   #3
trickykid
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I've seen apache run as nobody as well, along with many other services so they're not run as root.
 
Old 07-18-2008, 07:40 AM   #4
FranDango
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Why would you want to set user 'nobody' to /dev/null anyway? What's the purpose for that?

Linux Archive

Last edited by FranDango; 09-20-2008 at 06:10 AM.
 
Old 07-18-2008, 04:59 PM   #5
Wekker
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chsh, cli command will change login shell

Quote:
Originally Posted by techemically View Post
i cannot set it to /dev/null. I get permission denied.
1. echo "/dev/null" >> /etc/shells
2. as user root type; chsh /dev/null nobody

See man chsh for explanation.
 
Old 07-19-2008, 11:00 AM   #6
techemically
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???

i was told that With a shell of /dev/null, an attacker could not be certain whether the attempted user exists on the system -- not the case where /bin/false or /bin/nologin is the shell.

so i enter; su
then root passwd;
then; chsh /dev/null nobody
i get; Usage: chsh [options] [LOGIN]

Options:
-h, --help display this help message and exit
-s, --shell SHELL new login shell for the user account

to set nobody now to /dev/null do need to just enter; chsh /dev/null nobody -s?

also, are there any potential problems in doing so? sorry but i am VERY new to this.
 
Old 07-19-2008, 01:08 PM   #7
jomen
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In light of these option-hints I think the command would have to be:
chsh -s /dev/null nobody
or
chsh --shell/dev/null nobody
 
Old 07-20-2008, 05:39 PM   #8
techemically
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Thanks! :)

that did it! you guys are awesome. Since I have used MS systems for so long and support them professionally I am very unfamiliar with Linux in every aspect ( although i do have to say even being as new to it as i am, i am WAY happier to use it than any MS product i have ever seen). I am a pretty big security guy so if anyone could point me to some references on tools to be used in securing my Linux box i would appreciate it. Also, guarddog vs. firestarter, any opinions?
 
Old 09-06-2008, 11:56 PM   #9
aus9
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EDIT

found your link you read here

Successful su for nobody by root? post 8

http://www.linuxquestions.org/questi...05#post2555505

cheerio

Last edited by aus9; 09-07-2008 at 07:52 PM.
 
  


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