copy-backups-elsewhere.md

Copy backups elsewhere

After you've installed EffectiveDiscussions, you should copy the backups to a safety backup server, regularly. That's what this document is about.

(I'd like to simplify all this, by creating an rsync-read-only backup help Docker container.)

Create SSH key

On the backup server, preferably located in another datacenter, create a SSH key:

ssh-keygen -t rsa -b 4096 -f ~/.ssh/id_remotebackup -C "Automated remote backup"

You can perhaps skip the passphrase, since the backup server will have read-only rsync access only, all backups will be available on the backup server anyway. So a passhprase doesn't give any additional security.

Enable rrsync

On the EffectiveDiscussions (ED) server, enable rrsync (restricted rsync):

zcat /usr/share/doc/rsync/scripts/rrsync.gz > /usr/local/bin/rrsync
chmod ugo+x /usr/local/bin/rrsync

rsync keys

Then create a backup user with an authorized_keys file that allows restricted rsync:

# (still on the ED server)
useradd -m remotebackup
su - remotebackup
mkdir .ssh
echo 'command="/usr/local/bin/rrsync -ro /opt/ed-backups/",no-agent-forwarding,no-port-forwarding,no-pty,no-user-rc,no-X11-forwarding' >> .ssh/authorized_keys

Copy the public key on the backup server:

# on the backup server:
cat ~/.ssh/id_remotebackup.pub

copy the output

Append the public key to the last line in authorized_keys on the ED server:

# as user remotebackup: (!)
nano ~/.ssh/authorized_keys

# append a space and then the stuff you just copied to the last line (which is perhaps the only line).
# Do not paste it on a new line.

The result should be that the authorized_keys file looks like: (and it's a really long line)

command=..... ssh-rsa AAAA................ Automated remote backup

Test

Now, on the backup server, test to copy backups:

# replace 'serveraddress' with the server address
rsync -e "ssh -i .ssh/id_remotebackup" -av remotebackup@serveraddress:/ ed-backups/

	# todo: can I prefix .ssh with ~/ so will work from any directory?

Schedule copying-of-backups

If the above test works, then schedule a cron job to copy backups regularly. Do this on the backup server:

# (replace 'serveraddress' with the server address)
crontab -l | { cat; echo '@hourly rsync -e "ssh -i .ssh/id_remotebackup" -av remotebackup@serveraddress:/ ed-backups/ >> cron.log 2>&1'; } | crontab -

Now you'll have fresh backups of your forum in ~/ed-backups/, in case the ED server disappears.

(Why do we run the rsync client read-only on the backup server? Well, because if we were to let the ED server connect and write to the backup server, then someone who breaks in to the ED server could ransomware-encrypt all backups (that is, encrypt everything and tell you "give me money, only then will I unencrypt your data so you can read it again"). But when the ED server doesn't have access to the backup server, this cannot happen. Note that it should be easier to make the backup server safe, because it doesn't need to run the whole ED tech stack.)