As you know the /tmp partition is one of the most vulnerable places on your system. This tutorial will learn you how to secure it.
Securing Your /tmp Partition.
It would be worthwhile to give /tmp it’s own partition and mount it using noexec- This would protect your system from MANY local and remote exploits of rootkits being run from your /tmp folder.
What we are doing is creating a file that we will use to mount at /tmp. So log into SSH and SU to root so we may being!
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:
/sbin/mke2fs /dev/tmpMnt
Backup your /tmp dir- Other programs may use it to store cache files or whatever.
code:
cd /
code:
cp -R /tmp /tmp_backup
Mount the new /tmp filesystem with noexec
code:
mount -o loop,noexec,nosuid,rw /dev/tmpMnt /tmp
code:
chmod 1777 /tmp
Copy everything back to new /tmp and remove backup
code:
cp -R /tmp_backup/* /tmp/
code:
rm -rf /tmp_backup
Now we need to add this to fstab so it mounts automatically on reboots.
code:
pico -w /etc/fstab
You should see something like this:
code:
/dev/hda3 / ext3 defaults,usrquota 1 1
/dev/hda1 /boot ext3 defaults 1 2
none /dev/pts devpts gid=5,mode=620 0 0
none /proc proc defaults 0 0
none /dev/shm tmpfs defaults 0 0
/dev/hda2 swap swap defaults 0 0
At the bottom add
code:
/dev/tmpMnt /tmp ext2 loop,noexec,nosuid,rw 0 0
(Each space is a tab)
Save it!
Ctrl + X and Y
It’s done- /tmp is now mounted as noexec. This means nothing can be executed there 😉
