311 lines
14 KiB
Plaintext
311 lines
14 KiB
Plaintext
Internet Software Consortium
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Dynamic Host Configuration Protocol Distribution
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Version 2, Beta 1, Patchlevel 18
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March 5, 1998
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This is the first Beta release of Version 2 of the Internet Software
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Consortium DHCP Distribution. In version 2.0, this distribution
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includes a DHCP server, a DHCP client, and a BOOTP/DHCP relay agent.
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This beta is believed to be fairly stable. However, DHCP server users
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running a production environment should probably still use version
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1.0, which is more stable, having been in a feature freeze since
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November of 1996.
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In this release, the server and relay agent currently work well on
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NetBSD, Linux, FreeBSD, BSD/OS, Ultrix, Digital Alpha OSF/1, and SunOS
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4.1.4. They can also be run usefully on Solaris as long as only one
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broadcast network interface is configured. They also runs on QNX as
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long as only one broadcast network interface is configured and a host
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route is added from that interface to the 255.255.255.255 broadcast
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address. If you are running a Linux 2.0.30 or previous kernel, the
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DHCP daemons will only be able to operate on machines with a single
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network interface.
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The DHCP client currently only knows how to configure the network on
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NetBSD, FreeBSD, BSD/os, Linux, Solaris and NextStep. The client
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depends on a system-dependent shell script to do network
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configuration - support for other operating systems is simply a matter
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of porting this shell script to the new platform.
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If you wish to run the DHCP Distribution on Linux, please see the
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Linux-specific notes later in this document. If you wish to run on an
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SCO release, please see the SCO-specific notes later in this document.
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You particularly need to read these notes if you intend to support
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Windows 95 clients. If you are running a version of FreeBSD prior to
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2.2, please read the note on FreeBSD. If you are running HP-UX or
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Ultrix, please read the notes for those operating systems below.
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If you are running NeXTSTEP, please see the notes on NeXTSTEP below.
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If you start dhcpd and get a message, "no free bpf", that means you
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need to configure the Berkeley Packet Filter into your operating
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system kernel. On NetBSD, FreeBSD and BSD/os, type ``man bpf'' for
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information. On Digital Unix, type ``man pfilt''.
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BUILDING THE DHCP DISTRIBUTION
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To build the DHCP Distribution, unpack the compressed tar file using
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the tar utility and the gzip command - type something like:
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zcat dhcp-2.0b1pl18.tar.gz |tar xvf -
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Now, cd to the dhcp-2.0b1pl18 subdirectory that you've just created and
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configure the source tree by typing:
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./configure
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If the configure utility can figure out what sort of system you're
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running on, it will create a custom Makefile for you for that
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system; otherwise, it will complain. If it can't figure out what
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system you are using, that system is not supported - you are on
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your own.
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Once you've run configure, just type ``make'', and after a while
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you should have a dhcp server. If you get compile errors on one
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of the supported systems mentioned earlier, please let us know.
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If you get warnings, it's not likely to be a problem - the DHCP
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server compiles completely warning-free on as many architectures
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as we can manage, but there are a few for which this is difficult.
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If you get errors on a system not mentioned above, you will need
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to do some programming or debugging on your own to get the DHCP
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Distribution working.
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Once you have successfully gotten the DHCP Distribution to build, you
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can install it by typing ``make install''. If you already have an old
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version of the DHCP Distribution installed, you may want to save it
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before typing ``make install''.
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LINUX
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There are three big LINUX issues: the all-ones broadcast address,
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Linux 2.1 ip_bootp_agent enabling, and operations with more than one
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network interface. There are also two potential compilation/runtime
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problems for Linux 2.1/2.2: the "SO_ATTACH_FILTER undeclared" problem
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and the "protocol not configured" problem.
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LINUX: SO_ATTACH_FILTER UNDECLARED
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In addition, there is a minor issue that we will mention here because
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this release is so close on the heels of the Linux 2.2 release: there
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is a symlink in /usr/include that points at the linux asm headers. It
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appears to be not uncommon that this link won't be updated correctly,
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in which case you'll get the following error when you try to build:
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lpf.c: In function `if_register_receive':
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lpf.c:152: `SO_ATTACH_FILTER' undeclared (first use this function)
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lpf.c:152: (Each undeclared identifier is reported only once
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lpf.c:152: for each function it appears in.)
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The line numbers may be different, of course. If you see this
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header, your linux asm header link is probably bad, and you should
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make sure it's pointing to correct linux source directory.
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LINUX: PROTOCOL NOT CONFIGURED
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One additional Linux 2.1/2.2 issue: if you get the following message,
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it's because your kernel doesn't have the linux packetfilter
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configured:
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Can't install packet filter program: Protocol not available
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exiting.
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If this happens, you need to edit your linux kernel .config file, set
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CONFIG_FILTER=y, and rebuild your kernel. If the preceding sentence
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made no sense to you, ask your Linux vendor/guru for help - please
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don't ask us.
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LINUX: BROADCAST
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In order for dhcpd to work correctly with picky DHCP clients (e.g.,
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Windows 95), it must be able to send packets with an IP destination
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address of 255.255.255.255. Unfortunately, Linux insists on changing
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255.255.255.255 into the local subnet broadcast address (here, that's
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192.5.5.223). This results in a DHCP protocol violation, and while
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many DHCP clients don't notice the problem, some (e.g., all Microsoft
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DHCP clients) do. Clients that have this problem will appear not to
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see DHCPOFFER messages from the server.
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It is possible to work around this problem on some versions of Linux
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by creating a host route from your network interface address to
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255.255.255.255. The command you need to use to do this on Linux
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varies from version to version. The easiest version is:
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route add -host 255.255.255.255 dev eth0
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On some older Linux systems, you will get an error if you try to do
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this. On those systems, try adding the following entry to your
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/etc/hosts file:
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255.255.255.255 all-ones
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Then, try:
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route add -host all-ones dev eth0
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Another route that has worked for some users is:
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route add -net 255.255.255.0 dev eth0
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If you are not using eth0 as your network interface, you should
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specify the network interface you *are* using in your route command.
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LINUX: IP BOOTP AGENT
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Some versions of the Linux 2.1 kernel apparently prevent dhcpd from
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working unless you enable it by doing the following:
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echo 1 >/proc/sys/net/ipv4/ip_bootp_agent
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LINUX: MULTIPLE INTERFACES
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Most older versions of the Linux kernel do not provide a networking
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API that allows dhcpd to operate correctly if the system has more than
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one broadcast network interface. However, Linux 2.0 kernels with
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version numbers greater than or equal to 2.0.31 add an API feature:
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the SO_BINDTODEVICE socket option. If SO_BINDTODEVICE is present, it
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is possible for dhcpd to operate on Linux with more than one network
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interface. In order to take advantage of this, you must be running a
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2.0.31 or greater kernel, and you must have 2.0.31 or later system
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headers installed *before* you build the DHCP Distribution.
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We have heard reports that you must still add routes to 255.255.255.255
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in order for the all-ones broadcast to work, even on 2.0.31 kernels.
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In fact, you now need to add a route for each interface. Hopefully
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the Linux kernel gurus will get this straight eventually.
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SCO
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SCO has the same problem as Linux (described earlier). The thing is,
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SCO *really* doesn't want to let you add a host route to the all-ones
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broadcast address. One technique that has been successful on some
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versions of SCO is the very bizarre command:
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ifconfig net0 alias 10.1.1.1 netmask 8.0.0.0
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Apparently this works because of an interaction between SCO's support
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for network classes and the weird netmask. The 10.* network is just a
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dummy that can generally be assumed to be safe. Don't ask why this
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works. Just try it. If it works for you, great. If not, SCO is
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supposedly adding hooks to support real DHCP service in a future
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release - I have this on good authority from the people at SCO who do
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*their* DHCP server and client.
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HP-UX
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HP-UX has the same problem with the all-ones broadcast address that
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SCO and Linux have. One user reported that adding the following to
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/etc/rc.config.d/netconf helped (you may have to modify this to suit
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your local configuration):
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INTERFACE_NAME[0]=lan0
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IP_ADDRESS[0]=1.1.1.1
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SUBNET_MASK[0]=255.255.255.0
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BROADCAST_ADDRESS[0]="255.255.255.255"
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LANCONFIG_ARGS[0]="ether"
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DHCP_ENABLE[0]=0
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ULTRIX
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Now that we have Ultrix packet filter support, the DHCP Distribution
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on Ultrix should be pretty trouble-free. However, one thing you do
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need to be aware of is that it now requires that the pfilt device be
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configured into your kernel and present in /dev. If you type ``man
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packetfilter'', you will get some information on how to configure your
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kernel for the packet filter (if it isn't already) and how to make an
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entry for it in /dev.
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FreeBSD
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Versions of FreeBSD prior to 2.2 have a bug in BPF support in that the
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ethernet driver swaps the ethertype field in the ethernet header
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downstream from BPF, which corrupts the output packet. If you are
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running a version of FreeBSD prior to 2.2, and you find that dhcpd
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can't communicate with its clients, you should #define BROKEN_FREEBSD_BPF
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in site.h and recompile.
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NeXTSTEP
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The NeXTSTEP support uses the NeXTSTEP Berkeley Packet Filter
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extension, which is not included in the base NextStep system. You
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must install this extension in order to get dhcpd or dhclient to work.
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SOLARIS
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One problem which has been observed and is not fixed in this
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patchlevel has to do with using DLPI on Solaris machines. The symptom
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of this problem is that the DHCP server never receives any requests.
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If you are using Solaris 2.6, and you encounter this symptom, and
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you are running the DHCP server on a machine with a single broadcast
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network interface, you may wish to edit the includes/site.h file and
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uncomment the #define USE_SOCKETS line. Then type ``make clean;
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make''.
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The DHCP client on Solaris will only work with DLPI. If you run it
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and it just keeps saying it's sending DHCPREQUEST packets, but never
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gets a response, you may be having DLPI trouble as described above.
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If so, you are SOL. Also, because Solaris requires you to "plumb" an
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interface before it can be detected by the DHCP client, you must
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either specify the name(s) of the interface(s) you want to configure
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on the command line, or must plumb the interfaces prior to invoking
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the DHCP client. This can be done with ``ifconfig iface plumb'',
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where iface is the name of the interface (e.g., ``ifconfig hme0
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plumb'').
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It should be noted that Solaris versions from 2.6 onward include a
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DHCP client that you can run with ``/sbin/ifconfig iface dhcp start''
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rather than using the ISC DHCP client. The feature set of the Solaris
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client is different (not necessarily better or worse) than that of the
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ISC client, but in most cases it will be a lot easier for you to just
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use that. Please do not ask for help in using the Solaris DHCP client
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on Internet Software Consortium mailing lists - that's why you're
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paying Sun the big bucks. If you're having a problem with the
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Solaris client interoperating with the ISC dhcp server, that's another
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matter, but please check with Sun first.
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SUPPORT
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The Internet Software Consortium DHCP server is not a commercial
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product, and is not supported in that sense. However, it has
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attracted a fairly sizable following on the Internet, which means that
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there are a lot of knowledgable users who may be able to help you if
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you get stuck. These people generally read the dhcp-server@fugue.com
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mailing list.
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If you are going to use dhcpd, you should probably subscribe to the
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dhcp-server and dhcp-announce mailing lists. If you will be using
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dhclient, you should subscribe to the dhcp-client mailing list.
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PLEASE DO NOT send queries about non-isc clients to the dhcp-client
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mailing list. If you're asking about them on an ISC mailing list,
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it's probably because you're using the ISC DHCP server, so ask there.
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Please see http://www.fugue.com/dhcp/lists for details on how to
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subscribe. If you don't have WorldWide Web access, you can send mail
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to dhcp-request@fugue.com and tell me which lists you want to
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subscribe to, but please use the web interface if you can, since I
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have to handle the -request mailing list manually, and I will give you
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the third degree if you make me do your subscription manually.
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PLEASE DO NOT SEND REQUESTS FOR SUPPORT DIRECTLY TO ME! The number of
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people using the DHCP Distribution is sufficiently large that if I
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take an interrupt every time any one of those people runs into
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trouble, I will never get any more coding done.
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PLEASE DO NOT CALL ME ON THE PHONE FOR SUPPORT! Answering the phone
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takes a lot more of my time and attention than answering email. If you
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do call me on the phone, I will tell you to send email to the mailing
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list, and I won't answer your question, so there's no point in doing
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it.
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BUGS
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This release of the DHCP Distribution does not yet contain support for
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DHCPINFORM. Support for DHCPINFORM will be present in the release at
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a later time. DHCPINFORM is somewhat tangential to the main purpose
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of the DHCP protocol, so this probably won't be a major problem for
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most users.
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Vendor tags and User tags are not currently supported.
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