Two ISP connections
Barney Wolff
barney at databus.com
Wed Dec 10 17:39:35 PST 2003
On Thu, Dec 11, 2003 at 01:37:52AM -0500, Andrea Venturoli wrote:
> ** Reply to note from Barney Wolff <barney at databus.com> Wed, 10 Dec 2003 11:39:00 -0500
>
>
> > I don't know of anything published that does this, but it's easy to
> > write a perl or shell script that pings the router at the adsl isp
> > and does the necessary things when it disappears and reappears.
>
> Mmh, only problem is one of the ISP is famous for blocking ICMP as a whole, so no pings work. I haven't tried this
> particular line yet, but I may need to use come other protocol.
You can substitute anything that should get a response via isp1, and whose
result can be tested easily.
> > You start it from /usr/local/etc/rc.d (Hint - use nohup to keep it running).
> Why nohup?
Things started from /usr/local/etc/rc.d get a hup signal when rc is finished
with all the startup scripts - I think. Anyway, if you don't use nohup,
or a more-conventional way to daemonize what you've started, it will die
mysteriously in a very short time. I've never seen anybody else use nohup
for this purpose but it works just fine on both 4.x and 5.x.
> > Without getting much fancier than is reasonable, existing connections
> > will be dropped at switchovers.
>
> I can easily live with that.
>
> > I have a script that does similar things running here; email me if you
> > want it.
>
> Why not! If you don't mind, the please send it to me :)
http://www.databus.com/dslsec.tgz
(FreeBSD lists don't allow attachments.)
Anyone is welcome to use/copy/modify these scripts. For the two-isp
problem, if you're using NAT, you probably have to kill natd, reconfigure
it and restart it in the dslsec-gopri/gosec scripts.
--
Barney Wolff http://www.databus.com/bwresume.pdf
I'm available by contract or FT, in the NYC metro area or via the 'Net.
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