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Old 29-07-2004, 22:09   #1
shawnho
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HOWTO - Mount /tmp with noexec, nosuid, nodev

This guide is for those people whose /tmp is not mounted in its own partition and you want to refrain people using /tmp to abuse or compromise your system.

Step 1: Gain root access to your server.

Step 2: Check your system /etc/fstab file to ensure there is no /tmp mounting option.

Code:
cat /etc/fstab | grep /tmp

Step 3: Create a file that we will use to mount at /tmp.

Change your current working directory to /dev.

Code:
 cd /dev

Create 100MB file for our /tmp partition. If you need more space, make count size larger.

Code:
 dd if=/dev/zero of=tmpMnt bs=1024 count=100000

Make an extended filesystem for our tmpMnt file.

Code:
mke2fs /dev/tmpMnt

Step 4: Backup your /tmp directory.
Code:
 
cd /
cp -R /tmp /tmp_backup

Step 5: Take note of the ownership of those files in /tmp directory.
Code:
 
ls -al /tmp
Quote:
total 196
drwxrwxrwt 6 root root 12288 Sep 17 19:40 .
drwxr-xr-x 29 root root 4096 Sep 17 19:40 ..
drwxrwxrwt 2 xfs xfs 4096 Jul 9 2002 .font-unix
srwxrwxrwx 1 root root 0 Aug 21 14:53 .qmail-qread
srwxrwxrwx 1 root root 0 Aug 21 14:53 .qmail-qstat
-rw------- 1 apache apache 1453 Sep 17 13:42 sess_14430570035b5d63dfdd3a27d4f61f97
-rw------- 1 apache apache 18012 Sep 17 11:59 sess_44ed9ae94f17adb5eddd4e134fb4e08b
-rw------- 1 apache apache 82458 Sep 17 19:29 sess_8eebd968ab581fd308cefd8815bc4b06
-rw------- 1 apache apache 34934 Sep 17 16:07 sess_996fc03b8cf393b9ececf34c8a9d4fb2
-rw------- 1 apache apache 656 Sep 17 14:06 sess_9a4bf568ed741bc6a198e5281929d9fc
-rw------- 1 apache apache 1453 Sep 17 12:16 sess_b7aa7f9856ffd5168760d5d23c432919
-rw------- 1 apache apache 4548 Sep 17 12:21 sess_f8a87a3f8449b2959ae6c369dc2dbf77
-rw------- 1 root root 0 Sep 17 19:21 session_mm_apache0.sem
drwx------ 2 root root 4096 Jul 12 2002 ssh-XXHpPJi9
drwx------ 2 root root 4096 Jul 16 2002 ssh-XXkpNabM
drwx------ 2 root root 4096 Aug 15 2002 ssh-XXPX4k06
Step 6: Modify /etc/fstab file and add /tmp mounting option.

Code:
 
/dev/tmpMnt /tmp ext2 loop,nosuid,noexec,nodev,noatime,rw 0 0

Step 7: Mount the new /tmp filesystem with noexec etc.

Code:
 
mount -o loop,nosuid,noexec,nodev,noatime,rw /dev/tmpMnt /tmp

Step 8: Chmod 1777 /tmp.

Code:
chmod 1777 /tmp

Step 9: Check any error for /etc/fstab mounting option in /etc/fstab file.

Code:
mount -o remount /tmp

Step 10: Copy everything back from /tmp_backup to new /tmp.

Code:
cp -R /tmp_backup/* /tmp/

Step 11: Verify the files in the new /tmp directory and remove the backup directory.
Code:
   
ls -al /tmp
rm -rf /tmp_backup

Step 12: Change ownership or whatever if those files in /tmp changed as compared in step 5. Use the below as an example.

Code:
chown owner:group /tmp/file

Step 13: Remove /var/tmp and create a symlink to /tmp.
Code:
   
rm -rf /var/tmp
ln -s /tmp /var/tmp
Done


HOWTO courtesy of Choon
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Old 29-01-2010, 16:13   #2
WebhostingCS
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Great HowTo... keep it coming...!
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Old 15-05-2010, 20:30   #3
vheeds
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Hello Shawnho,

Good work! This will definitely help the newbies.
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