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Re: Ip Aliasing the Debian Way...



On Wed, Jan 24, 2001 at 04:36:14PM -0800, Willy Lee wrote:
> Nathan E Norman wrote:
> > 2) You're missing the "network" line from your iface stanza.  Since it
> > looks to me like you're adding a different subnet this is kinda
> > important.
> 
> Ok, I thought (from man interfaces) that the "network" line was only
> needed
>  for 2.0.x series kernels, I can add this.

You could be right there :)  It never hurts to add information
(especially in this case as you'll see).

You're running 2.2, right?  I assume you have aliasing compiled into
the kernel since you're able to bind an ip address to eth0:0

> > 3) It doesn't look like you added any routes.  This might not be
> > necessary depending which kernel you're using.
> 
> I tried several combinations of route commands.  This is the latest one
> I tried:
> 
> route add -host 205.178.55.110 dev eth0:0
> 
> I also tried 'route add -net 205.178.55.0 netmask 255.255.255.192 dev
> eth0:0'.

[ snip ]
> iface eth0:0 inet static
>         address 205.178.55.110
>         netmask 255.255.255.192
>         gateway 205.178.55.65
>         broadcast 205.178.55.255
>         network 205.178.55.0

I see a problem.  205.178.55.110 is not in the network 205.178.55.0/26
(255.255.255.192 is a 26 bit network mask).  You want the network
205.178.55.64/26.  Replace "205.178.55.0" with "205.178.55.64" in your
iface stanza and that route statement, and see what happens.

I'm trying to think of a good reference for classless routing (aka
variable-length subnet).  It's not hard to learn, but it can be
daunting to the newcomer.

I'm also not sure that having two gateway lines is a good thing.
Usually a router knows about one default gateway unless it wants to do
some sort of round-robin load balancing, and I'm quite sure you have
to choose extra bits in teh kernel config to do that.  Perhaps comment
out one or the other.  Are 205.178.55.65 and 10.0.0.41 the same
router?

> trs80:/etc/network# route -n
  ^^^^  love the hostname :)
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric Ref    Use
> Iface
> 205.178.55.64   0.0.0.0         255.255.255.192 U     0      0        0

This is the route that the kernel added automatically, I guess.  Note
the network is 205.178.55.64 rather than 205.178.55.0.  Hmm, perhaps
the problem here is that the route is bound to eth0 rather than
eth0:0, but I'm not so sure about that.

> Thanks for all the help.
> I am kinda struggling here, since I've been forced into a sysadmin role
> without
> any experience or training (company can't afford a real sysadmin, I'm
> the only 
> person with *any* kind of linux experience, since I run debian at home.)

Well, you've got a good start imo; I learned everything I needed to
know about routing from running Linux :)

(Ok, most everything).

Good luck,

-- 
Nathan Norman - Staff Engineer | A good plan today is better
Micromuse Inc.                 | than a perfect plan tomorrow.
mailto:nnorman@micromuse.com   |   -- Patton

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