ClamAV Live CD update script

Brandon Perry has created a very handy live CD for running Clam AV. One of the tricks with CD’s like this though is that the virus definitions need to be continually updated.

He graciously addressed this by writing up a script that automates that process of updating the definitions and re-creating the CD. I checked it out and decided to make a couple improvements. Mostly things to make it more portable and maintainable. Here is my version (note that there may be some wrapping problems so a direct copy/paste will be a problem. Yay for no attachments.):

#!/bin/bash

iso=”ClamAVLiveCD2.0″
ver=”2.0″

if [ "$UID" -ne "0" ]
then
echo “This script will only work when run by “root”.”
exit 1
fi

# not everyone will have squash tools, install them if not found
if [ ! `which unsquashfs` ]
then
aptitude install squashfs-tools
fi

# not everyone will have genisoimage, install it if not found
if [ ! `which mkisofs` ]
then
aptitude install genisoimage
fi

START=$(date +%s)

mkdir iso
mount $iso.iso iso/ -o loop

cp -R iso/ image/

echo “Decompressing SquashFS…”
cp iso/casper/filesystem.squashfs ./
unsquashfs filesystem.squashfs

echo “Setting up Live CD chroot…”
cp /etc/resolv.conf squashfs-root/etc/resolv.conf

chroot squashfs-root/ mount /proc
chroot squashfs-root/ mount /sys
chroot squashfs-root/ mount -t devpts none /dev/pts

echo “Refreshing and updating ClamAV virus definitions…”
chroot squashfs-root/ freshclam

#cleanup chroot
echo “Cleaning up chroot…”
chroot squashfs-root/ rm -rf /tmp/*
chroot squashfs-root/ rm /etc/resolv.conf
chroot squashfs-root/ umount -l -f /proc
chroot squashfs-root/ umount -l -f /sys
chroot squashfs-root/ umount /dev/pts

echo “Removing old SquashFS filesystem…”
rm image/casper/filesystem.squashfs

echo “Creating new SquashFS filesystem…”
mksquashfs squashfs-root image/casper/filesystem.squashfs

echo “Finding and creating MD5 hash sums of files in image…”
cd image
find . -type f -print0 | xargs -0 md5sum > md5sum.txt

cd ..
echo “Creating new image…”
mkisofs -r -V “ClamAV Live CD $ver” -cache-inodes -J -l \
-b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot \
-boot-load-size 4 -boot-info-table -o $iso_new.iso image/

# Make sure that mkisofs succeeded before we try moving or renaming
# any images.
if [ $? != "0" ]
then
echo “mkisofs failed with error code: $?”
exit
fi

echo “Renaming new image, and moving original image to old…”
mv $iso.iso $iso_old.iso
mv $iso_new.iso $iso.iso

#cleanup working directory

echo “Cleaning up working directory…”
umount iso/

rm -rf squashfs-root
rm -rf image
rm -rf iso
rm filesystem.squashfs

echo “Getting MD5 and SHA1 sum of image…”
echo “MD5: ” > clamavlivecd.sums
md5sum $iso.iso >> clamavlivecd.sums
echo “SHA1: ” >> clamavlivecd.sums
sha1sum $iso.iso >> clamavlivecd.sums

END=$(date +%s)

echo “Done at `date`. The whole process took $(($END – $START)) seconds!”