It should be quiet simple (for cable network):
Open as root the existing file /etc/netctl/eth0 using nano (nano /etc/netctl/eth0).
Edit your desired IP method, address and gateway like this example:
Description='A basic static ethernet connection'
Interface=eth0
Connection=ethernet
IP=static
Address=('192.168.178.20/24') #your wanted address /24 that every machine from your LAN can reach the rune-server
Gateway='192.168.178.1' #your gateway address
DNS=('192.168.178.1') #your nameserver(s)
#Routes=('192.168.0.0/24 via 192.168.1.2')
## For IPv6 autoconfiguration
#IP6=stateless
## For IPv6 static address configuration
#IP6=static
#Address6=('1234:5678:9abc:def::1/64' '1234:3456::123/96')
#Routes6=('abcd::1234')
#Gateway6='1234:0:123::abcd'
(The text after the #-sign are only comments or disabled functions.)
Then type sync and reboot. After doing this you should reach the ssh and http ports over the new ip address.
Another way:
cp /etc/netctl/examples/ethernet-static /etc/netctl/eth0
nano /etc/netctl/eth0
+++ Make your changes in the file (and do not write this line
)+++
CTRL-x and y for exit nano and save the edited file
sync
reboot
A sample of examples for cable and wifi you can find in the folder /etc/netctl/examples/.
Hint: You should only have one eth0 file in the folder /etc/netctl/. If you want to have a backup of the original file copy or move the original file to the folder /etc/netctl/examples.
More information to netctl here:
https://wiki.archlinux.org/index.php/Netctl
