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List:       openbsd-misc
Subject:    Re: netbooting OpenBSD (6.0) i386 and amd64 clients from one server
From:       Sven-Volker Nowarra <peb.nowarra () bluewin ! ch>
Date:       2017-01-29 16:27:48
Message-ID: D09CCADE-EA4A-4D57-932B-40E845E5375E () bluewin ! ch
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> Am 29.01.2017 um 14:23 schrieb Jiri B <jirib@devio.us>:
>
>>> Isn't better to use rewrite/file remapping instead of hacking pxeboot?
>>> If an i386 machine would request /etc/boot.conf via tftp you could
rewrite
>>> it to (based on fact you know that that machine is i386 - during
provisioning)
>>> /etc/i386/boot.conf. For the client I suppose it would still think it
gets
>>> /etc/boot.conf.
>
> A POC...
>
> j.
>
> ~~~
> #!/usr/bin/perl -w
>
> use IO::Socket::UNIX;
>
> my $socket_path = '/tmp/tftpd_rewrite.sock';
> unlink $socket_path if -e $socket_path;
> my $socket = IO::Socket::UNIX->new(
>    Local  => $socket_path,
>    Type   => SOCK_STREAM,
>    Listen => SOMAXCONN,
> );
> die "Can't create socket: $!" unless $socket;
>
> while (1) {
>    next unless my $connection = $socket->accept;
>    $connection->autoflush(1);
>    while (my $line = <$connection>) {
>        chomp($line);
>        # XXX
>        # conditionals here
>        if ($line =~ /^127.0.0.1 read \/etc\/boot.conf$/) {
>            print $connection "/etc/boot.conf.i386\n";
>        } elsif ($line =~ /^\S+ read \/etc\/boot.conf$/) {
>            print $connection "/etc/boot.conf\n";
>        }
>    }
> }
> ~~~
>
> $ ./tftpd_rewrite
> $ doas chgrp _tftpd /tmp/tftpd_rewrite.sock ; doas chmod g+w
/tmp/tftpd_rewrite.sock
> $ doas tftpd -v -r /tmp/tftpd_rewrite.sock /home/vm
>
> $ tftp 127.0.0.1
> tftp> get /etc/boot.conf
> Received 38 bytes in 0.0 seconds
>
> $ syslogc daemon | tail -n1
> Jan 29 01:51:49 t440s tftpd[626]: 127.0.0.1: read request for
'/etc/boot.conf'
> $ cat boot.conf
> set tty com0
> boot tftp:/bsd.rd.i386

nice proof of concept :-)
thx! works well with OpenBSD's tftpd.
Same logic does not apply to in.tftpd or atftpd. I had copied the OpenBSD
"pxeboot" (amd64 and i386, they differ a bit) to my Linux box. As you can see
in the second line, the requested filename "boot.conf" has no additional IP
address or MAC to filter on:

  in.tftpd[2131]: RRQ from 192.168.88.253 filename /i386/bsd60_i386_pxeboot
> in.tftpd[2132]: remap: input: /etc/boot.conf
  in.tftpd[2132]: remap: done
  in.tftpd[2132]: RRQ from 192.168.88.253 filename /etc/boot.conf
  in.tftpd[2133]: remap: input: /etc/random.seed
  in.tftpd[2133]: remap: done
  in.tftpd[2133]: RRQ from 192.168.88.253 filename /etc/random.seed
  in.tftpd[2133]: sending NAK (1, File not found) to 192.168.88.253
  in.tftpd[2134]: remap: input: /bsd
  in.tftpd[2134]: remap: done
  in.tftpd[2134]: RRQ from 192.168.88.253 filename /bsd
  in.tftpd[2134]: sending NAK (1, File not found) to 192.168.88.253

This way, when creating a remapping based on the raw filename, it would apply
to i386 and amd64.
Anyhow, I will update my doc with the solution for OpenBSD. Already a good
step forwards.
At the same time I will also update with Anton's remark for a dual server.

thx, rgds,
Volker

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