How can I use multiple public connections in a fail-over setup?
In this example we have an ADSL modem on ppp0 and a CableModem on eth1. All referenced scripts can be found in a contrib directory, http://rcf.mvlan.net/dist/contrib/adsl-cable-failover/. The idea is to use the ADSL to host web servers, etc., and the CableModem for all outgoing stuff (like browsing the web from LAN PCs, outgoing e-mail, etc.). If one of the lines goes down, traffic should start using the other viable internet connection. This can all be done with routing. There’s no monitoring of anything involved. You need a process that runs in order to move incoming connections from one line to the other though. In this case, we assume you’re using a dynamic DNS, this is fairly easy. Monitor the ADSL line, if it goes down, update the dynamic DNS with the Cable’s IP (using the cable’s outgoing connection). Start monitoring the ADSL line, and when it comes back, update the DNS entries with the ADSL’s IP. What you need is a startup script called ‘route’ (created by Jean-Sbastien Moriss
