This is just a simple reference guide on howto display maintenance notice page for client when the the main internet link is down. You can add many advance functions in it, but I shared this method just to give you an idea that how it an be done. The result is that It can greatly help in reducing clients calls to help line in event of internet downtime.
As someone asked from the FB, I decided to make it public so those who don’t know about it should get a idea on how simple it is to achieve. I implemented this technique at a local network which had a fewer number of clients with an unstable PTCL DSL connectivity. It helped the operator to keep informed about the connectivity status via sms status (GSM modem was attached with mirkotik and the netwatch script also sends sms to the operator about the link status)
The theory is simple, First create a NAT rule that redirects http port 80 requests to your local/external proxy service which deny all requests and redirect to local web server page which shows the MAINTENANCE PAGE. make sure to disable this rule after its creation.
Now create a NETWATCH rule that can keep monitoring any reliable HOST on internet , probably your ISP DNS or GOOGLE DNS , if the link is down, then DOWN script should be triggered which enables the NAT Rule, so in case of any link down all users will be routed to maintenance page, and when the link gets UP, the up script will disable the NAT rule, and internet will start work at user end normally.
First the NAT rule which actually redirects port 80 requests to internet/external proxy server.
[Make sure the comments remains same in all rules of nat / netwatch, otherwise script will not work.
/ip firewall nat add action=redirect chain=dstnat comment="Redirect to Proxy" disabled=yes dst-port=80 protocol=tcp to-ports=8080
/ip proxy set always-from-cache=no cache-administrator=webmaster cache-hit-dscp=4 cache-on-disk=yes enabled=yes max-cache-size=unlimited max-client-connections=600 \ max-fresh-time=3d max-server-connections=600 parent-proxy=0.0.0.0 parent-proxy-port=0 port=8080 serialize-connections=no src-address=0.0.0.0 /ip proxy access add action=deny disabled=no dst-port="" redirect-to=10.0.0.1/netdown.html
Now the Netwatch script which will keep monitoring the internet, and act accordingly
/tool netwatch add disabled=no down-script=":log error \"ISP Link seems to be DOWN , ENABLING redirection to proxy so users will see mainteneace page / zaib\"\r\ \n/ip firewall nat enable [find comment=\"Redirect to Proxy\"]" host=22.214.171.124 interval=5s timeout=1s up-script=":log error \"ISP Link seems to be UP again , Disa\ bling redirection to proxy so users internet will start work again. / zaib\"\r\ \n/ip firewall nat disable [find comment=\"Redirect to Proxy\"]\r\ \n"
Result [when the internet link is down]:
You can achieve the same task with more elegance , more controlled way by using SCRIPTS to do various functions like frequency control , ping multiple hosts instead of single destination, Act according to latency load results, email / sms function, and much much more,
as someone said
” SKY IS THE ONLY LIMIT “