I am trying to serve dhcp out of eth2, eth0 is my optus internet connection. Can i specify in dhcp which interface to use?
syslog:
Jul 7 18:18:01 erupt dhcpd: No subnet declaration for eth0 (211.30.175.xxx).
Jul 7 18:18:01 erupt dhcpd: Please write a subnet declaration in your dhcpd.con
f file for the
Jul 7 18:18:01 erupt dhcpd: network segment to which interface eth0 is attached
.
Jul 7 18:18:01 erupt dhcpd: exiting.
# more /etc/network/interfaces auto lo iface lo inet loopback auto eth0 iface eth0 inet dhcp auto eth2 iface eth2 inet static address 192.168.6.1 netmask 255.255.255.0
# more /etc/dhcpd.conf option subnet-mask 255.255.255.0; default-lease-time 600; max-lease-time 7200;
subnet 192.168.6.0 netmask 255.255.255.0 { range 192.168.6.10 192.168.6.20;
}
I had a similar problem on my triple interface router/firewall box. It wants a declaration for each interface, but I only provide DHCP on the internal one. The way I got around it was to create two "empty" sections for the DMZ and Internet interface and configured the internal one how I wanted. Then I just added some iptables rules to drop DHCP requests/replies on the DMZ and Internet interfaces. Here's a sanitized version of my config file:
>cat /etc/dhcpd.conf
# dhcpd.conf # # Configuration file for ISC dhcpd #
# option definitions common to all supported networks... option domain-name "mydomain.foo.bar"; default-lease-time 7200; max-lease-time 14400;
# Internal network - allocate addresses between .100-150 subnet 10.0.0.0 netmask 255.255.255.0 { option ntp-servers 10.0.0.1; option time-servers 10.0.0.1; range 10.0.0.100 10.0.0.150; option domain-name-servers 10.0.0.1; option domain-name "mydomain.foo.bar"; option routers 10.0.0.1; option subnet-mask 255.255.255.0; option broadcast-address 10.0.0.255; }
# Internet interface - EMPTY, we dont provide DHCP! subnet 1.2.3.4 netmask 255.255.255.252 { deny unknown-clients; deny booting; }
# DMZ interface - EMPTY, we dont provide DHCP! subnet 1.2.4.5 netmask 255.255.255.224 { deny unknown-clients; deny booting; }
### SNIPPED the static IP group ###
<<< END OF /etc/dhcpd.conf >>>
Then just block UDP+TCP ports 67/68 on the interfaces you DONT want to use DHCP.
HTH
Cheers,
James -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html