Note: I had issues with installing this, thankfully the client seems to work fine. I have included a tar file with the missing html files that don't seem to appear in /var/lib/xymon/www/. You can try skipping the line that cp *html /var/lib/xymon/www and see if it works for you! If not, just CP over the files. It will be a little weird, but you will see my home XYMon page for a few minutes till XYMon refreshes, then you will just see the XYMon host itself. Make sure /etc/default/xymon and /etc/xymon/hosts.cfg match!
This is one of those situations were I got it to work "somehow" (I think I Upgraded my previous installation perhaps, but fresh install I can't make work without this tar ball), and tried to replicate the process for this guide, but was UNABLE to. I figured out the difference (the html files that are in the tar ball), and that if I moved over the tar file from the working one to the new one, it would reset to default and work.
apt-get update apt-get install -y wget apache2 php5 libapache2-mod-php5 php5-mcrypt librrd4 apt-get -f -y install cd ~ wget https://www.freesoftwareservers.com/wiki/files/3965332/5406768/1/1476239703102/XYMon_Server_4.3.27_amd64.tgz tar zxvf XYMon*.tgz
Install Server :
dpkg -i xymon*client*deb
dpkg -i xymon_*deb
sed -i 's/\(^XYMSRV=\).*/\XYMSRV="127.0.0.1"/' /etc/xymon/xymonclient.cfg
sed -i 's/\(^CLIENTHOSTNAME=\).*/\CLIENTHOSTNAME="HOSTNAME4-HOSTS.CFG"/' /etc/default/xymon-client && nano /etc/xymon/hosts.cfg
Make HOSTNAME4-HOSTS.CFG the same in xymon-client and hosts.cfg!
ufw allow 1984/tcp && ufw allow 1984/udp cp /etc/apache2/conf.d/xymon /etc/apache2/conf-available/xymon.conf cp *.html /var/lib/xymon/www/ ln -s /etc/apache2/conf-available/xymon.conf /etc/apache2/conf-enabled/ ln -s /etc/apache2/mods-available/authz_groupfile.load /etc/apache2/mods-enabled/ ln -s /etc/apache2/mods-available/cgi.load /etc/apache2/mods-enabled/ ln -s /usr/lib/xymon/server/ /var/www/html/xymon
Redirect domain.com to domain.com/xymon (Only if this is the only website you host on this machine):
sh -c 'echo "RedirectMatch ^/$ /xymon/" >> /etc/apache2/apache2.conf' sudo a2enmod rewrite && sudo service apache2 restart
/etc/init.d/apache2 restart &&/etc/init.d/xymon restart