DHCP

The following article describes how to use DHCP from inside a container. Note that it requires veth device.

Set up

Assumes you have set up vzbr0, as described on Virtual Ethernet device.

vzctl create 144 --ostemplate centos-4-i386-minimal
vzctl start 144
vzyum 144 install dhcp
vzctl set 144 --netif_add eth0 --save
brctl show

brctl addif vzbr0 veth144.0
ifconfig vzbr0
cat /proc/sys/net/ipv4/conf/vzbr0/forwarding 
cat /proc/sys/net/ipv4/conf/vzbr0/proxy_arp 
echo 1 > /proc/sys/net/ipv4/conf/vzbr0/forwarding 
echo 1 > /proc/sys/net/ipv4/conf/vzbr0/proxy_arp 

Instructions largely borrowed from http://oob.freeshell.org/nzwireless/dhcpd.html

Sample DHCPD.conf

# Sample /etc/dhcpd.conf

# Set DHCPD to answer requests on the wireless interface

DHCPDARGS=wlan0;

# Set some defaults for lease time and DNS update method
ddns-update-style ad-hoc;
default-lease-time 600;
max-lease-time 7200;

# Set the subnet mask for the wireless IP network
option subnet-mask 255.255.255.0;

# Set the Broadcast address. This will be 10.x.x.255,
# the "x.x" will depend upon the network assigned to you by NZWireless.
option broadcast-address 10.1.2.255;

# Set the router address, this will be 10.x.x.1, the address
# of your wireless interface WLAN0
option routers 10.1.2.1;

# Set the Name Server address. This will be the same as your WLAN0 address
# because we intend to run DNS on this machine.
option domain-name-servers 10.1.2.1;

# Set the default domain name for clients on this network.
# i.e. the DNS domain assigned to you by your wireless administrator.
option domain-name "simon.akld.nzwireless.org";

# Allocate a network range for dynamic IP addresses to hand out to clients.
# Again, this range will be in 10.x.x.x, depending upon the network allocated
# to you by your wireless administrator.
subnet 10.1.2.0 netmask 255.255.255.0 {
    range 10.1.2.10 10.1.2.20;
} 

Host$ cp /etc/sysconfig/network /vz/root/144/etc/sysconfig/network

vz144$ service dhcpd start

External links

• http://www.cpqlinux.com/dhcpd.html - create static IPs, debugging etc.
• http://mailman.vyatta.com/pipermail/vyatta-users/2007-September/001858.html - not configured to listen on any interfaces
• http://forum.openvz.org/index.php?t=msg&goto=22072& - diagnosis
• http://www.google.ca/search?q=DHCPDARGS+brctl - searches for help on getting a virtual bridge to work with DHCPD
• http://www.linuxfoundation.org/en/Net:Bridge - great explanation of bridging