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Re: RFC: new network config (was: Re: network configuration)

On Sat, Feb 06, 1999 at 05:19:25PM +1100, Craig Sanders wrote:
> ok, it seems to me that netbase probably doesn't need to configure
> IP addresses for virtual hosts. it just needs to configure the main
> addresses for each interface card.
> so how about we split it up like this:
>  - your netbase does the main interface setup.  whatever is need to get
> the machine up and running on the net.
>  - my virtual-services package does everything else needed for virtual
> host service provision, including running ifconfig for ip_alias
> addresses.
> (alternatively, if you want to handle ip_alias ifconfig in netbase,
> that's fine too. would be nice to have some extra data in your
> /etc/interfaces file, though...to avoid duplication of config data.)

What I was thinking of was something like:

	eth0   # This is my real IP
	eth1   # But I'm also a masq g/w for this network
	eth0:0	# I also run a virtual ftp server on this
				# address

	www.freakystuff.com	apache,analog
	ftp.freakystuff.com	proftpd

/etc/hosts		ftp.freakystuff.com		www.freakystuff.com

But yes, I see what you mean -- the eth0:0 line can be derived (with
difficulty) from the fact you're hosting services for ftp.freakystuff,
but you don't (yet) have ftp.freakystuff's IP.

Making it "eth0:0   ftp.freakystuff.com" *might* be more acceptable but
probably not all that much.

Something like:

/etc/init.d/virtual-services start:

	for each virtual service {
	    resolve address of virtual-hostname;
	    if ( we don't have an interface bound to that address ) {
                $added = 0;
	        for each non-alias interface {
	            if ( address & netmask == virtual-address & netmask ) {
	                add an alias for this interface with address v-a
	                $added = 1;
	        if ( !$added ) die("Eeek, can't guess interface");
           # we're receiving packets for that address now, hopefully. Woo :)

(which isn't all that different from the code you posted)

Hmmm. That *might* not be too hard, actually. Except for the "are we already
that address" and "for each non-alias interface", maybe.

Depending on how you wanted to do this, you could make it somewhat
easier by adding to /etc/interfaces yourself (just as you'll be adding
to /etc/apache/httpd.conf, and whatever else). That would mean you could
just read /etc/interfaces to work out which address you were using, which
would be a lot easier than stressing about parsing ifconfig's output.

	for each line {
		next if comment;
		($iface, $ip, @rest) = split(/ +/, $line);
		$hash{$ip} = $iface;

	if ( !$hash{$virt-ip} ) { ... }

	for (keys %hash) ...

> > better.
> i agree. we'll need to co-ordinate a few little things... mostly
> to avoid duplication of data - duplication is bad because it's
> depressingly easy to change something in one file and forget to make the
> corresponding change in another file.
> which is part of the point of this virtual-services package i'm writing
> - consolidate all the relevant data into one config file and generate
> other config files from that.


Anthony Towns <aj@humbug.org.au> <http://azure.humbug.org.au/~aj/>
I don't speak for anyone save myself. PGP encrypted mail preferred.

``Like the ski resort of girls looking for husbands and husbands looking
  for girls, the situation is not as symmetrical as it might seem.''

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