This is a basic security tip that can be executed to help protect your system. This is not an end-all guide for server security, admins must always be diligent.
At install time, the easiest thing to do is to mount your /tmp partition with the noexec,nosuid options, and mount the /home partition with the nosuid option. This is done in your /etc/fstab and requires those paths to exist as partitions, and not just as subdirectories of /.
Be very careful when editing your /etc/fstab, as any errors could prevent your system from starting up.
Backup your fstab:
cp /etc/fstab /etc/fstab.bak
Create 1GB tmpmnt partition file
cd /var dd if=/dev/zero of=tmpMnt bs=1024 count=1048576
Format new partition
mkfs.ext3 -j /var/tmpMnt
Press Y when asked
Backup old /tmp
cp -Rp /tmp /tmp_backup
Mount the new /tmp filesystem
mount -o loop,noexec,nosuid,rw /var/tmpMnt /tmp
Set the appropriate permissions
chmod 1777 /tmp
Copy files back to /tmp
cp -Rp /tmp_backup/* /tmp/
Add new /tmp to fstab
echo "/var/tmpMnt /tmp ext3 loop,rw,noexec,nosuid,nodev 0 0? >> /etc/fstab
Symlink /var/tmp to /tmp
rm -rf /var/tmp/ ln -s /tmp/ /var/tmp