Internet Software Consortium Dynamic Host Configuration Protocol Server Version 1.0 December 6, 1997 This is Version 1.0 of the Internet Software Consortium DHCP Server (ISC dhcpd). In this release, support for the core DHCP and BOOTP protocols are provided. This release currently works well on Digital Alpha OSF/1, SunOS 4.1.4, NetBSD, FreeBSD, BSD/OS and Ultrix. It can also be run usefully on Solaris as long as only one broadcast network interface is configured. It also runs on QNX and Linux as long as only one broadcast network interface is configured and a host route is added from that interface to the 255.255.255.255 broadcast address. If you wish to run dhcpd on Linux, please see the Linux-specific notes later in this document. If you wish to run on a SCO release, please see the SCO-specific notes later in this document. You particularly need to read these notes if you intend to support Windows 95 clients. If you are running a version of FreeBSD prior to 2.2, please read the note on FreeBSD. If you are running HP-UX, Ultrix or Digital UNIX, please read the notes for those operating systems below. BUILDING DHCPD To build dhcpd, type ``configure''. If configure can figure out what sort of system you're running on, it will create a custom Makefile for you for that system; otherwise, it will complain. If it can't figure out what system you are using, that system is not supported - you are on your own. Once you've run configure, just type ``make'', and after a while you should have a dhcp server. If you get compile errors on one of the supported systems mentioned earlier, please let us know. If you get errors on a system not mentioned above, you will need to do some programming or debugging on your own to get dhcpd working. LINUX There are two big LINUX issues: Linux 2.1 ip_bootp_agent enabling and the all-ones broadcast address. BOOTP AGENT ENABLING Also, some versions of the Linux 2.1 kernel apparently prevent dhcpd from working unless you enable it by doing the following: echo 1 >/proc/sys/net/ipv4/ip_bootp_agent BROADCAST In order for dhcpd to work correctly with picky DHCP clients (e.g., Windows 95), it must be able to send packets with an IP destination address of 255.255.255.255. Unfortunately, Linux insists on changing 255.255.255.255 into the local subnet broadcast address (here, that's 192.5.5.223). This results in a DHCP protocol violation, and while many DHCP clients don't notice the problem, some (e.g., all Microsoft DHCP clients) do. Clients that have this problem will appear not to see DHCPOFFER messages from the server. It is possible to work around this problem on some versions of Linux by creating a host route from your network interface address to 255.255.255.255. The command you need to use to do this on Linux varies from version to version. The easiest version is: route add -host 255.255.255.255 dev eth0 On some older Linux systems, you will get an error if you try to do this. On those systems, try adding the following entry to your /etc/hosts file: 255.255.255.255 all-ones Then, try: route add -host all-ones dev eth0 Another route that has worked for some users is: route add -net 255.255.255.0 dev eth0 If you are not using eth0 as your network interface, you should specify the network interface you *are* using in your route command. SCO SCO has the same problem as Linux (described earlier). The thing is, SCO *really* doesn't want to let you add a host route to the all-ones broadcast address. One technique that has been successful on some versions of SCO is the very bizarre command: ifconfig net0 alias 10.1.1.1 netmask 8.0.0.0 Apparently this works because of an interaction between SCO's support for network classes and the weird netmask. The 10.* network is just a dummy that can generally be assumed to be safe. Don't ask why this works. Just try it. If it works for you, great. If not, SCO is supposedly adding hooks to support real DHCP service in a future release - I have this on good authority from the people at SCO who do *their* DHCP server and client. HP-UX HP-UX has the same problem with the all-ones broadcast address that SCO and Linux have. One user reported that adding the following to /etc/rc.config.d/netconf helped (you may have to modify this to suit your local configuration): INTERFACE_NAME[0]=lan0 IP_ADDRESS[0]=1.1.1.1 SUBNET_MASK[0]=255.255.255.0 BROADCAST_ADDRESS[0]="255.255.255.255" LANCONFIG_ARGS[0]="ether" DHCP_ENABLE[0]=0 ULTRIX Now that we have Ultrix packet filter support, dhcpd on Ultrix should be pretty trouble-free. However, one thing you do need to be aware of is that it now requires that the pfilt device be configured into your kernel and present in /dev. If you type ``man packetfilter'', you will get some information on how to configure your kernel for the packet filter (if it isn't already) and how to make an entry for it in /dev. DIGITAL UNIX Digital Unix has one minor caveat - this version of the Internet Software Consortium DHCP server cannot currently coexist with rarpd. If you run dhcpd and rarpd together, dhcpd will never see any DHCP requests, because the RARP filter has a higher priority. FreeBSD Versions of FreeBSD prior to 2.2 have a bug in BPF support in that the ethernet driver swaps the ethertype field in the ethernet header downstream from BPF, which corrupts the output packet. If you are running a version of FreeBSD prior to 2.2, and you find that dhcpd can't communicate with its clients, you should #define BROKEN_FREEBSD_BPF in site.h and recompile. SUPPORT ISC DHCPD is not a commercial product, and is not supported in that sense. However, it has attracted a fairly sizable following on the Internet, which means that there are a lot of knowledgable users who may be able to help you if you get stuck. These people generally read the dhcp-server@fugue.com mailing list. If you are going to use dhcpd, you should probably subscribe to the dhcp-server and dhcp-announce mailing lists. For details, please see http://www.fugue.com/dhcp/lists. If you don't have WorldWide Web access, you can send mail to dhcp-request@fugue.com and tell me which lists you want to subscribe to, but please use the web interface if you can, since I have to handle the -request mailing list manually, and I will give you the third degree if you make me do your subscription manually. PLEASE DO NOT SEND REQUESTS FOR SUPPORT DIRECTLY TO ME! The number of people using dhcpd is sufficiently large that if I take an interrupt every time any one of those people runs into trouble, I will never get any more coding done. PLEASE DO NOT CALL ME ON THE PHONE FOR SUPPORT! Answering the phone takes a lot more of my time and attention than answering email. If you do call me on the phone, I will tell you to send email to the mailing list, and I won't answer your question, so there's no point in doing it. BUGS This release of dhcpd does not contain support for DHCPINFORM. Support for DHCPINFORM will be present in the next release. DHCPINFORM is somewhat tangential to the main purpose of the DHCP protocol, so this probably won't be a major problem for most users. Vendor tags and User tags are not currently supported.