What’s the main problem with running a server at home – the 50% uptime figure… (OK, it’s not that bad 🙂

One of my Zoneedit passwords expired the other day and I forgot to change it on the server (duh)…

So – I created a really simple cron script to check all the expected services are up at each domain I host. It does this by connecting to a remote server (assuming you have SSH access to some external machine) and attempting to connect back to each domain on a particular port. I check for SMTP and HTTP.

And here it is:
[sourcecode language=’sh’]
#!/bin/bash
#
# Script to test if all the domains are up and working.
# It upens a connection to a remote server and tries to connect
# back to the given port of each domain. If the connect fails, or times out
# this script prints an error to stderr and returns false.
#
# To use, make this file executable and make a cronjob to run it or place
# the script in /etc/cron.hourly.
#
# Wilson Waters 20100824
#

# domains to test (space separeted list)
DOMAINS=”mail.mydomain.com mail.someother.domain.”

# remote server to test from
SERVER=””

# port to try and connect to
PORT=25

# timeout on connect after this many seconds
TIMEOUT=5

#user to connect to the remote host as
USER=”root”

#—————————————————————————

error=0
for domain in $DOMAINS
do
command=”ssh $USER@$SERVER nc -z -w$TIMEOUT $domain $PORT”
output=`$command 2>&1`
if [ $? -ne 0 ]; then
error=1
echo “Connect error $domain:$PORT ($output)” >&2
fi
done

exit $error
[/sourcecode]

UPDATE
I recently updated this script to be a little more useful and robust. It now sends mail directly from the script (rather than via cron) and allows you to set a port for each host.

[sourcecode language=’sh’]
#!/bin/bash
#
# Script to test if all the domains are up and working.
# It upens a connection to a remote server and tries to connect
# back to the given port of each domain. If the connect fails, or times out
# this script prints an error to stderr and returns false.

# domains to test (space separeted list)
DOMAINS=”mail.alintech.com.au www.alintech.com.au:80:”

# remote server to test from
SERVER=”somedomain.net”

# port to try and connect to
DEFAULT_PORT=25

# timeout on connect after this many seconds
TIMEOUT=5

MAIL_RECIPIENT=blablabla@alintech.com.au

#—————————————————————————

for domain in $DOMAINS
do
# work out the port
port=$DEFAULT_PORT
IFS=’:’ read -ra addr <<< "$domain" if [[ ${#addr[@]} = 2 ]]; then domain=${addr[0]} port=${addr[1]} fi # ping it if [ "X$SERVER" == "X" ]; then command="nc -v -z -w$TIMEOUT $domain $port" else command="ssh $SERVER nc -v -z -w$TIMEOUT $domain $port" fi output=`$command 2>&1`
res=$?
output=”${output}\nTime: `date`”
if [ $res -ne 0 ]; then
echo -e $output | /usr/bin/mail -s “Connect error $domain” $MAIL_RECIPIENT
fi
done
[/sourcecode]

Interesting video on “hacking” the google WiFi location service from the “black hat” conference.

http://www.securityweek.com/hacker-uses-xss-and-google-streetview-data-determine-physical-location

The basic gist of it is

1. Create malicious html page which tries to load local router status pages in hidden iframes – i.e. http://192.168.1.1/router.asp?status, http://10.0.0.1/index.shtml, etc…
2. Use javascript to parse DOM tree and read the status page text (and WiFi router MAC address).
3. Send MAC address back to server (via JSON/POST, etc)
4. Perform lookup on Google location service using discovered MAC address
5. Google returns location of discovered MAC address.

Of course, this only woks if the users browser same origin policy allows parsing the DOM tree of the iframe, which I think most browsers would disallow…

I went looking at my home router status page and, sure enough, it shows the WiFi MAC address on the status page which is accessible on the local network without logging on.

I haven’t posted anything for a while as the result of a bad case of integer overflow.

Many months ago, I thought I’d dust of the old photo gallery and upload some more photos. After numerous failures I realized PHP has a POST limit of only 4 MB and I was trying to upload 5MB+ photos. This took me quite a while to work out, as it failed without an error. I thought a good solution was to up the limit to something big. 2GB should be more than enough for anyone!

When that still didn’t work I just gave up and posted the photos somewhere else.

Little did I know that I’d just broken almost everything php on that server. It took a couple of months before I finally realized that the max size of an int on this platform is about 2 billion… and  post_max_size = 2048M in php.ini actually wraps to -2048MB or so. duh.

So back to it!