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SET UP A PXE BOOT SERVER ON THE NETWORK
Install OpenBSD on a box with more than one network interface. Set the server up on the network with the primary interface active and configured to talk on the network.Configure the 2nd interface on a private subnet for dhcp and tftp use by the new PXE box.
SET UP ACCESS TO THE BOOT SERVER
edit /etc/sysctl.conf /etc/rc.conf and enable packet filtering and forwardingedit pf.conf to resemble the following simple, limited access structure ext_if="sis0"
int_if="sis1"
set skip on lo
scrub in all
nat on $ext_if from !($ext_if) -> ($ext_if:0)
block in
pass out
pass quick on $int_if no state
pass in quick on $ext_if proto tcp from 159.212.48.138 to ($ext_if) port ssh
antispoof quick for { lo $int_if }


GET THE PXE FILES
This box needs to download or acquire the latest PXE boot files from the OpenBSD project.If you need to go through a proxy, you should set env variable like following example. export http_proxy="http://proxy.blah.com:8080"
You can check this with the env command.Then use wget specifying the --proxy-user=username and --proxy-password=password as needed. An example follows: wget --proxy-user=someuser --proxy-password=p4ssw0rd http://openbsd.mirrors.hoobly.com/4.3/i386/pxeboot
You will also need to get the ramdisk kernel bsd.rdThe Files can also be transfered from another server where they were downloaded. scp is recommended.

SET UP DHCP TO BOOT THE PXE BOX
add something like the following to your dhcp.conf file, note the filename "pxeboot"; directive - this should be set to the name of your PXE boot file.
shared-network LOCAL-NET {
option domain-name "boot.net";
option domain-name-servers 159.212.72.72, 159.212.99.99;

subnet 10.0.10.0 netmask 255.255.255.0 {
option routers 10.0.10.1;
filename "pxeboot";
range 10.0.10.100 10.0.10 150;
default-lease-time 3600;
max-lease-time 10800;
}
}

make sure to set your hostname.* file for the 2nd interface to the corresponding IP address of the option routers setting, in this example 10.0.10.1add the name of your 2nd interface to the dhcp.interfaces filestart dhcpd manually with the following (user your own device name) dhcpd sis1
check for dhcpd running with ps aux | grep dhcpd
if it's not running, check for errors with cat /var/log/messages | grep -i dhcp


SET UP TFTP TO SERVE THE FILES
uncomment (remove the #) the line in /etc/inetd.conf as follows: #tftp dgram udp wait root /usr/libexec/tftpd tftpd -s /tftpboot
create the directory in the above line /tftpbootplace the pxeboot and bsd.rd files in the /tftpboot directoryyou may want to create an etc subdir and put a boot.conf file in it.sample /tftpboot/etc/boot.conf for a soekris install would looke like this: stty com0 19200
set tty com0
either use a line in the boot.conf to specify the bsd.rd or rename the file bsd.rd to simply bsdrestart inetd (not sure if this is needed, but I did it) pkill inetd
inetd

SOEKRIS INSTALL
Plug a crossover cable in to the 2nd interface of your INSTALL SERVER and the primary interface of the server you wish to install on.Boot the new server and enter the boot BIOS by typing CTL-P on a Soekris box.Give the PXE boot command boot f0
Its a regular OpenBSD install from here.