Date: Mon, 22 Dec 1997 11:18:42 -0500 From: Keith Jackson <KJackson@smtp-gw.lsuc2.lsuc.on.ca> To: Studded@dal.net, kjackson@lsuc.on.ca Cc: freebsd-questions@freebsd.org Subject: Re: ISC DHCP server (beta5.16) and Berkeley Packet Filter -Reply Message-ID: <s49e4cb5.052@smtp-gw.lsuc2.lsuc.on.ca>
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>>> Studded <Studded@dal.net> 12/22/97 12:07am >>> Keith Jackson wrote: > > Hi, I recently downloaded a copy of the Internet Software Consorium's > DHCP daemon (beta5.16) from their web site Good choice. Keith says: Well, I didn't have a lot of choice. It was either ISC or some commercial crap and I have neither the money nor the support from managament when I need it to get a commercial one. Also, I'd heard that ones like the Microsoft one and others sometimes were not backward compatible in the sense that they had no support for bootp, which some devices still use. Typical of Microsoft. I read an article sometime around when Win95 first came out (it only has support for DHCP) about the various DHCP servers and was disturbed to discover how different they were and how they seemed not to be supporting the features that they ought to have. I don't know of any other public domain DHCP server, if it exists. But the ISC one seems to have paid attention to the RFCs regarding DHCP which is better than what one could say for the commercial ones. Perhaps the situation with those has changed but I don't know. Meanwhile ISC gives me a server which works in all the ways I need it to work and I can test it and scripts to build the DHCP conf file long before I need it to be critical. We're planning to convert desktops to WIn95 in the next 6 months or so and we have been using bootp up til now. But, I need DHCP for Win95 (thanks Bill Gates, praise be upon him :-) ). I don't want to be hardcoding IP addresses in our workstations. :-) > and compiled it without > errors on a FreeBSD 2.1.0 system we're running here. Hmmm.. I started with FreeBSD around 2.1.5, but from what you describe it sounds like you're on exactly the right track. Keith says: Actually, I thought it was 2.1.5 too but the motd file reports it as 2.1.0 but that may be wrong. > I have since discovered this is referring to something called the > Berkeley Packet Filter. I must assume this is not enabled by default on > FreeBSD systems and that I must add this device to the kernel? > It also seems to indicate that I must use the Berkeley Packet Filter > if I wish to use the ISC DHCP daemon. Is this correct? If so, do all > DHCP daemons require this to be enabled. I understand there is a > security risk to turning on the Berkeley Packet Filtering. > If I include a pseudo-device line in our kernel config file and > rebuild the kernel, will this be sufficient to enable BPF? Use the entry in LINT, recompile the kernel, and then you will need to use the MAKEDEV script in /dev to make bpf0 - bpf3. IIRC, dhcpd uses two bpf sockets, so you should be fine with the default of 4. If you need more, increase the line in your kernel file and make the appropriate devices. To my knowledge, all dhcp systems use bpf's. It is pretty important that you do not allow untrusted users on your dhcp server for that reason. Keith says: Right. Thanks. Good luck, Doug PS, if you need your clients to set their hostname, mail me and I'll send you my hack to the client script for that. It may find its way into the next beta, but it definitely works. :) Keith says: Hmm. This is interesting. I was assuming (based on my experience with our bootp servers, which do assign the hostname) that DHCP would also do this (given that my thinking about DHCP is that it is a superset of bootp). But I had noticed that WIn95 wants you to enter the hostname before turning on DNS querying on it (and I was hoping for a way around this because it means you have to visit each desktop). Is this a way of getting clients such as WIn95 boxes to acquire their hostname from the DHCP server? What's the client script you're referring to?
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