Re: Checking line status

["Gáspár Lajos" <swifty@freemail.hu>]

Hi!

I have written a target for this:  www.glsys.eu/iface

Swifty

John Lister írta:
> Hi, I have a multihomed machine to which i'd like to check the status 
> of each line periodically. I want to do this so that I can modify the 
> iptables rules and send new connections out over the active lines and 
> restore service when the line comes back up.
>
> I thought I could use ping with the -I option, but that doesn't seem 
> to work, it always uses the default route. However if I get rid of the 
> default route and modify the rules to match the packets I get a 
> "network unreachable" message without it ever hitting iptables. For 
> example adding something like this never gets matched for the ping.
>
> iptables -t mangle -I OUTPUT -j LOG --log-prefix "output: "
>
> Normally ping results in ICMP messages being traversed, but not this 
> time.
>
> Could someone explain what is going on and I'd be grateful if there 
> were any suggestions on other ways to detect if a line is down - 
> simply looking in /proc/net/dev or similar wouldn't help as the local 
> connection is likely to be up, but the physical line to the ISP may be 
> down.
>
>
> Thanks
>
> John
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