DHCP servers, non DEC interfaces and Packet filtering

From: Jonathan Nicholson <jjn_at_sanger.ac.uk>
Date: Fri, 23 Jan 1998 14:34:23 +0000 (GMT)

Hi,

I'm trying to set up a DHCP server on Digital Unix 4.0B I'm not terribly
convinced of joind, so I'm looking at the ISC's dhcp server
(http://www.isc.org/dhcpd) as this will allow me to specify the interface
I wish to bind to.

The reason for this is that there is a DHCP server running on our ethernet
network which supplies PCs with real (global unique) IP addresses, however
we with to set up a 'bogus' class B network for internal use (using
172.25.x.x) which also requires a DHCP server.

The DHCP service needs to be running on a Dunix box with interfaces into
both the 172.25.x.x network and our real IP blocks.

I don't want the DHCP server that is serving the 172.25.x.x network to
give a 172.25.x.x number to a PC that needs to be global unique, so I want
to be able to restrict listening for DHCP to the 172.25.x.x interface.

The problem:-

The 172.25.x.x interface is an ATM Emulated LAN (E-LAN) running on Fore
Systems cards. This is not a DEC interface and is not recognised by the
kernel as an interface.

The isc DHCPD requries packet filtering to work, I cannot get packet
filtering to work on the elan interfaces, the interfaces show up as el?
so on this machine I have:-

el0: flags=463<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST>
     inet 192.168.10.51 netmask ffffff00 broadcast 192.168.10.255 ipmtu 1500

el1: flags=463<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST>
     inet 193.62.207.93 netmask ffffff00 broadcast 193.62.207.255 ipmtu 1500

el2: flags=463<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST>
     inet 172.25.20.10 netmask ffff0000 broadcast 172.25.255.255 ipmtu 1500


but if I try to check out packet filtering:-

byron[root]83: pfconfig el2
pfopen: el2: Interrupted system call
pfconfig: your system may not be properly configured; see "man packetfilter"


Any ideas?

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= Jonathan Nicholson - System Administrator +44 1223 494987 (internal 4987) =
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Received on Fri Jan 23 1998 - 15:35:56 NZDT

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