Message-ID: <4940092B.30306@nothome.org>
Date: Wed, 10 Dec 2008 13:23:39 -0500
From: Nathan Angelacos <nangel@nothome.org>
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To: Harry Lachanas <grharry@freemail.gr>, 
 Alpine Developers <alpine-devel@lists.alpinelinux.org>
Subject: Re: [alpine-devel] bridge + problems
References: <493FEC83.3020801@freemail.gr>
In-Reply-To: <493FEC83.3020801@freemail.gr>
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Harry,

> The pre-down section complaints about pre-down entries being duplicates
> as you can see I have  comment out the down parts to bring the interface 
> up ...

You've run into (yet another) busybox ifupdown weirdness.   pre-down is 
not a valid keyword - but instead of reporting that, it says you have 
duplicates.  (evidently you are allowed to have a "foobar" keyword in 
each stanza, but not two... ?!

It appears to be a pretty common mistake to think there's a pre-down 
command (that would be logical)  but the actual command is "down"

so you have

pre-up (before iface is "up")
up (should be called post-up)

down (should be called pre-down)
post-down (after interface is "down")


The following adjustments should work:


auto br0
iface br0 inet static
	address 192.168.2.254
	netmask 255.255.255.0
	pre-up /usr/sbin/openvpn --mktun --dev tap0
	pre-up /bin/ip link set tap0 up
         pre-up /bin/ip link set eth3 up
         pre-up /usr/sbin/brctl addbr br0
         pre-up /usr/sbin/brctl addif br0 eth3
         pre-up /usr/sbin/brctl addif br0 tap0

         down /usr/sbin/brctl delif br0 eth3
         down /bin/ip link set eth3 down
         down /usr/sbin/brctl delif br0 tap0
         down /bin/ip link set tap0 down
         post-down /usr/sbin/brctl delbr br0
         post-down /usr/sbin/openvpn --rmtun --dev tap0


One last thing that you might want to keep in mind:  the sequence of 
*-up/down commands will stop whenever the *first* one returns false.

For example, adding this line before the delif br0 eth3 ...

        down false
        down /usr/sbin/brctl delif br0 eth3
        .
        .

Will never actually run the delif/iplink/openvpn commands.  That makes 
it possible to get into ifup/down hell where ifup says the device is 
already up, and ifdown won't let you take it down.

I'm mention this so that if you ever run a command that *might* return 
false, you should escape it:

        down /usr/sbin/command_that_might_fail || true
                                              ^^^^^^^^^

The "|| true" forces the command to be true. Problem solved. :-)


And, since I'm responding after natanael did, we have a fundamental 
difference of opinion on bridges - I think they are interfaces (they 
show up in ip link) so they should go in the interfaces file.   He 
prefers the init.d script.   Take your pick - either way will work.

> BTW: No daemontools ?????  should I compile my own ??

Natanael really likes busybox init :-)   Send in a patch and I'm sure 
he'll add it though.

> I know I can use inittab for this but I hate it ...
> 
> 
> Cheers..
> 
> ( Thanks Nathan, NC )
> 
> Nathan U R Greek, correct ???
> 

Mostly the name.  My father's father was greek - but I mostly take after 
my Hungarian mom... (Greeks+Hungarians... talk about hard-headed!)


By the way, thanks very much for your work on muli-isp failover - its 
VERY much appreciated!


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