I am installing the Nagios NRPE check_ide_smart monitor on my remote host system. I have set the suid bit to 4750 and the file, check_ide_smart executes just fine. The problem is that I don't know how to access the /dev/sda file with the appropriate permissions. I get the following error:
nagios@stormguard:/usr/loc
CRITICAL - Couldn't open device /dev/sda: Permission denied
I am a bit confused on how to allow access to /dev/sda but keep a strong security.
Thanks.
Rob
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Thanks. I tried your suggestion and here is what happened:
nagios@stormguard:/usr/loc
CRITICAL - SMART_ENABLE: Permission denied
CRITICAL - SMART_CMD_ENABLE
Here is the file listing if this helps:
nagios@stormguard:/usr/loc
-rwsr-x--- 1 nagios nagios 61715 2009-08-05 12:18 check_ide_smart
Thanks for the help.
Rob
Ok, those were the obvious things now start digging......
it appears to have to do with the disk itself...
http://www.mail-archive.co
If I try it on a system with SCSI & SATA disks then it fails with the same error
CRITICAL - SMART_ENABLE: Permission denied
CRITICAL - SMART_CMD_ENABLE
Also for root..... on SCSI disks, but it works as expected for SATA disks.
although smartctl reports in full on both (for root).
On a different system with the same sata type controller, with different disks:
it reports the expected results, also for that systems PATA disks.
For root:
/usr/lib/nagios/plugins/ch
OK - Operational (30/30 tests passed)
For nagios:
CRITICAL - SMART_ENABLE: Permission denied
CRITICAL - SMART_CMD_ENABLE
The same error is returned...
smartctl for root returns all info...
smartctl for nagios returns...:
--8<--
nagios$ smartctl -a /dev/hdb
smartctl version 5.38 [i686-pc-linux-gnu] Copyright (C) 2002-8 Bruce Allen
Home page is http://smartmontools.sourc
Smartctl: Device Read Identity Failed (not an ATA/ATAPI device)
A mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.
--8<--
With permissive there are new error messages indicating it cannot turn on the smart options.
When running check_ide_smart under strace it ends with:
--8<--
........
open("/dev/hda", O_RDONLY|O_LARGEFILE) = 3
ioctl(3, 0x31f, 0xbfb15608) = -1 EACCES (Permission denied)
fstat64(1, {st_mode=S_IFCHR|0600, st_rdev=makedev(136, 0), ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
write(1, "CRITICAL - SMART_ENABLE: Permissi"..., 43CRITICAL - SMART_ENABLE: Permission denied
) = 43
write(1, "CRITICAL - SMART_CMD_ENABLE\n"..., 28CRITICAL - SMART_CMD_ENABLE
) = 28
exit_group(2) = ?
--8<--
Showing that the open succeeeds, but the IOCTL for the smart command still fails....,
this might be a kernel issue.
From the kernel source I can see that CAP_SYS_ADMIN is required to be able to do IOCTL commands to the device.....
Now the puzzle startw to give sysadmin rights to the nagios user...
Probably it is easiest to
chown root:root /usr/lib/nagios/plugins/ch
chmod u+s /usr/lib/nagios/plugins/ch
chmod o+x /usr/lib/nagios/plugins/ch
ls -l /usr/lib/nagios/plugins/ch
-rwsr-x--x 1 root root 18052 Aug 11 21:56 /usr/lib/nagios/plugins/ch
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Answer for Membership
by: nociPosted on 2009-08-10 at 04:11:41ID: 25058739
Security is ownership based.
You need to add the username nagios runs under to be added to the group that is owner of the device...
ls -l /dev/sda show you the owner & group of the device (probably: root, disk)
In that case add the nagios user (probably: nagios) to the group disk in the /etc/group file like:
From:
disk::123:hal
To:
disk::123:hal,nagios
So keep the names & number already there, and add the nagios user to the ,-separated list.