So I’ve used pingdom for years to monitor servers/services related to my hosting business www.serve-you.net. They offer a great service at a reasonable price, so I don’t have to setup my own monitoring hosts. They have tons of monitoring servers around the globe, which is a good way to not only monitor the up/down status, but also latency/page load times, etc.
The problem I often have though, is that monitoring servers are added/removed fairly often. I usually have pretty strict firewall rules on my servers, so allowing these servers is a must, since the activities that they perform is often seen as an attack. Pingdom publishes a list of active servers in the control panel, but keeping up with this and manually updating my firewall rules (I use CSF on my cPanel servers) can be a pain. Luckily Pingdom also has an RSS feed with the server list, though it’s in XML format of course. So I finally got around to setting up a script to automate updating the firewall rules daily with this list.
Some quick research on this subject found that CSF has a variable in it’s config called GLOBAL_ALLOW that allows you to feed LFD a list of IP’s via a URL. This is great! However, it requires the list to be in plain text, with one IP per line. As I stated above, the list provided by Pingdom is an XML file, so of course this needs to be massaged in order to be fed to CSF directly.
# The follow Global options allow you to specify a URL where csf can grab a
# centralised copy of an IP allow or deny block list of your own. You need to
# specify the full URL in the following options, i.e.:
# The actual retrieval of these IP's is controlled by lfd, so you need to set
# LF_GLOBAL to the interval (in seconds) when you want lfd to retrieve. lfd
# will perform the retrieval when it runs and then again at the specified
# interval. A sensible interval would probably be every 3600 seconds (1 hour).
# A minimum value of 300 is enforced for LF_GLOBAL if enabled
# You do not have to specify both an allow and a deny file
# You can also configure a global ignore file for IP's that lfd should ignore
LF_GLOBAL = Default: 0 [0 or 60-604800]
So I wrote a quick and dirty script which grabs the RSS feed, pulls the IP’s only, and puts them in a file with one IP per line. I then take this list and copy it to a location on a web server, and set the GLOBAL_ALLOW to get this once a day. Success! Next step was to automate it via cron, and make sure that we have a backup list (I setup 5 backups, in case I don’t notice right away).
The crontab entry:
45 23 * * * /root/scripts/update_pingdom_ips.sh >/dev/null 2>&1
# Grab the latest pingdom monitoring IP's from their RSS feed, and translate them to IPLIST for CSF/LFD.
mv pingdom_ips pingdom_ips-$DATE
until [ $DONE -eq 1 ]
TOTAL_FILES=`echo "$FILES" | wc -l`
if [ $TOTAL_FILES -gt $MAX_BACKUPS ]
OLD_FILES=`echo "$FILES" | head -1`
wget https://www.pingdom.com/rss/probe_servers.xml -O /root/probe_servers.xml -o /dev/null
cat /root/probe_servers.xml | grep IP | sed -e 's/.*IP: //g' | sed -e 's/; Host.*//g' | grep -v IP > /root/pingdom/pingdom_ips
cp /root/pingdom/pingdom_ips /PATH/TO/WEBROOT/pingdom_ips