Weblog entry #22 for dkg
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#22
using debian system-created user accounts?
Posted by dkg on Fri 14 Sep 2007 at 21:47
Does anyone use the backup user for doing local system backups? or do you create a new user specifically for that?
I ask because backup is debian-specific uid 34, provided by the base-passwd package. But reading /usr/share/doc/base-passwd/users-and-groups.txt.gz, i find only this:
backup
Presumably so backup/restore responsibilities can be locally delegated to
someone without full root permissions?
HELP: Is that right? Amanda reportedly uses this, details?
So fellow admins: do you use debian-allocated accounts (i.e., with uid < 100) (other than root) for any local (non-distro) purpose? If so, when do you do so? if not, why not?
Comments on this Entry
Yes, I use Amanda, and it does default to using the 'backup' account on Debian. On regular Debian installations, permissions on the relevant devices are already set:
# id -a backup uid=34(backup) gid=34(backup) groups=34(backup),6(disk),26(tape) # ls -al /dev/hda? brw-rw---- 1 root disk 3, 1 Mar 14 2002 /dev/hda1 brw-rw---- 1 root disk 3, 2 Mar 14 2002 /dev/hda2 brw-rw---- 1 root disk 3, 3 Mar 14 2002 /dev/hda3 brw-rw---- 1 root disk 3, 4 Mar 14 2002 /dev/hda4 brw-rw---- 1 root disk 3, 5 Mar 14 2002 /dev/hda5 brw-rw---- 1 root disk 3, 6 Mar 14 2002 /dev/hda6 brw-rw---- 1 root disk 3, 7 Mar 14 2002 /dev/hda7 brw-rw---- 1 root disk 3, 8 Mar 14 2002 /dev/hda8 brw-rw---- 1 root disk 3, 9 Mar 14 2002 /dev/hda9 # ls -al /dev/st? crw-rw---- 1 root tape 9, 0 Mar 14 2002 /dev/st0 crw-rw---- 1 root tape 9, 1 Mar 14 2002 /dev/st1 # ls -al /dev/nst? crw-rw---- 1 root tape 9, 128 Mar 14 2002 /dev/nst0 crw-rw---- 1 root tape 9, 129 Mar 14 2002 /dev/nst1So why wouldn't I want to use the backup account for this?
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Posted by dkg (166.84.xx.xx) on Sun 16 Sep 2007 at 22:29
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Interesting. on my local system that user isn't part of those groups at all:
[0 dkg@squeak ~]$ id -a backup uid=34(backup) gid=34(backup) groups=34(backup) [0 dkg@squeak ~]$But to answer your question with another question, why would you want your backup user to have write access to the main block devices you're backing up from? Write access to /dev/hda1 seems like too much power for a backup user to me.
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Beats me. I'd guess "tradition", but that's entirely a guess. I suppose that if all the following conditions were met, giving backup rw permission to block devices would be required:
- You use dump/restore to back up devices instead of tar or some higher-level tool
- You want a non-root user to be able to restore a given block device
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