README 10.7 KB
Newer Older
Ted Lemon's avatar
Ted Lemon committed
1
		     Internet Software Consortium
2
	   Dynamic Host Configuration Protocol Distribution
Ted Lemon's avatar
Ted Lemon committed
3 4
			 Development Snapshot
			  November 22, 1997
5

Ted Lemon's avatar
Ted Lemon committed
6 7
This is a development snapshot of work in progress on version 2.0 of
the Internet Software Consortium DHCP Distribution.  In version 2.0,
8
this distribution includes a DHCP server, a DHCP client, and a
Ted Lemon's avatar
Ted Lemon committed
9 10 11 12 13 14
BOOTP/DHCP relay agent.  The engineering snapshot has become a lot
more stable since the last snapshot, and will soon go into beta.
However, DHCP server users running a production environment should
probably still use the latest version on the 1.0 release branch, which
is more stable, having been in a feature freeze since November of
1996.
15 16 17

In this release, the server and relay agent currently work well on
Digital Alpha OSF/1, SunOS 4.1.4, NetBSD, FreeBSD, BSD/OS and Ultrix.
18 19 20 21
They can also be run usefully on Solaris as long as only one broadcast
network interface is configured.  They 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
Ted Lemon's avatar
Ted Lemon committed
22 23
address.  If you are running a Linux 2.0.31 kernel, the DHCP daemons
may be able to operate on more than one interface.
24

Ted Lemon's avatar
Ted Lemon committed
25 26 27 28 29
The DHCP client currently only knows how to configure the network on
NetBSD, FreeBSD, BSD/os, Linux, Solaris and NextStep.  The client
depends on a system-dependent shell script to do network
configuration - support for other operating systems is simply a matter
of porting this shell script to the new platform.
30 31 32 33 34 35 36 37

If you wish to run the DHCP Distribution 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 or
Ultrix, please read the notes for those operating systems below.
Ted Lemon's avatar
Ted Lemon committed
38
If you are running NeXTSTEP, please see the notes on NeXTSTEP below.
39

40 41 42 43 44
If you start dhcpd and get a message, "no free bpf", that means you
need to configure the Berkeley Packet Filter into your operating
system kernel.   On NetBSD, FreeBSD and BSD/os, type ``man bpf'' for
information.   On Digital Unix, type ``man pfilt''.

Ted Lemon's avatar
Ted Lemon committed
45

46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61
		    BUILDING THE DHCP DISTRIBUTION

To build the DHCP Distribution, 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 the DHCP Distribution working.

				LINUX

62 63 64
There are three big LINUX issues: the all-ones broadcast address,
Linux 2.1 ip_bootp_agent enabling, and operations with more than one
network interface.
Ted Lemon's avatar
Ted Lemon committed
65 66 67

                              BROADCAST

68 69 70 71 72
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
Ted Lemon's avatar
Ted Lemon committed
73 74
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
75
see DHCPOFFER messages from the server.
Ted Lemon's avatar
Ted Lemon committed
76

77 78 79 80
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:
Ted Lemon's avatar
Ted Lemon committed
81

82
	route add -host 255.255.255.255 dev eth0
Ted Lemon's avatar
Ted Lemon committed
83

84 85 86
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:
Ted Lemon's avatar
Ted Lemon committed
87

88
255.255.255.255	all-ones
Ted Lemon's avatar
Ted Lemon committed
89

90
Then, try:
Ted Lemon's avatar
Ted Lemon committed
91

92
	route add -host all-ones dev eth0
Ted Lemon's avatar
Ted Lemon committed
93

94
Another route that has worked for some users is:
Ted Lemon's avatar
Ted Lemon committed
95

96
	route add -net 255.255.255.0 dev eth0
Ted Lemon's avatar
Ted Lemon committed
97

98 99
If you are not using eth0 as your network interface, you should
specify the network interface you *are* using in your route command.
Ted Lemon's avatar
Ted Lemon committed
100

101 102 103 104 105 106 107 108
			    IP BOOTP AGENT

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


Ted Lemon's avatar
Ted Lemon committed
109 110 111
                        MULTIPLE INTERFACES

Most older versions of the Linux kernel do not provide a networking
Ted Lemon's avatar
Ted Lemon committed
112 113 114 115 116 117 118 119
API that allows dhcpd to operate correctly if the system has more than
one broadcast network interface.  However, Linux 2.0 kernels with
version numbers greater than or equal to 2.0.31 add an API feature:
the SO_BINDTODEVICE socket option.  If SO_BINDTODEVICE is present, it
is possible for dhcpd to operate on Linux with more than one network
interface.  In order to take advantage of this, you must be running a
2.0.31 or greater kernel, and you must have 2.0.31 system headers
installed *before* you build dhcpd.
Ted Lemon's avatar
Ted Lemon committed
120

121 122 123 124 125 126 127
NOTE: People have been having problems finding the 2.0.31 kernel
because it was only available as a prerelease patch.   As of October
17, Linux 2.0.31 is the stable Linux kernel, and is available as a
kernel distribution rather than as a test patch.   With any luck, it
will be in the latest version of your favourite Linux distribution
soon.

Ted Lemon's avatar
Ted Lemon committed
128 129
If you are running a Linux 2.1 kernel, this does not guarantee that you
have SO_BINDTODEVICE.   Linux 2.0.31 was released quite a while after 2.1
130 131
kernel development began.   The earliest Linux kernel in the 2.1
development stream with SO_BINDTODEVICE is version 2.1.68.
Ted Lemon's avatar
Ted Lemon committed
132

Ted Lemon's avatar
Ted Lemon committed
133 134 135 136 137
We have heard reports that you must still add routes to 255.255.255.255
in order for the all-ones broadcast to work, even on 2.0.31 kernels.
In fact, you now need to add a route for each interface.   Hopefully
the Linux kernel gurus will get this straight eventually.

138
				 SCO
Ted Lemon's avatar
Ted Lemon committed
139

140 141 142 143
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:
Ted Lemon's avatar
Ted Lemon committed
144

145
	ifconfig net0 alias 10.1.1.1 netmask 8.0.0.0
Ted Lemon's avatar
Ted Lemon committed
146

147 148 149 150 151 152 153
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.
Ted Lemon's avatar
Ted Lemon committed
154

155 156 157
				HP-UX

HP-UX has the same problem with the all-ones broadcast address that
158 159 160 161 162 163 164 165 166 167
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
168

169 170 171 172 173 174 175 176 177 178 179 180 181
The above hack supposedly does not work on HP-UX version 9.x.
However, another hack which supposedly _does_ work on 9.x is to add
the following entry to your /etc/hosts or DNS database:

255.255.255.255 all-ones

Then modify the broadcast as follows (change to suit your
configuration, of course):

ifconfig lan0 [your ip addr] netmask [your netmask]  broadcast all-ones

I would appreciate any reports as to how well this works for you.

182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199
				ULTRIX

Now that we have Ultrix packet filter support, the DHCP Distribution
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.

			       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.
Ted Lemon's avatar
Ted Lemon committed
200

Ted Lemon's avatar
Ted Lemon committed
201 202 203
                              NeXTSTEP

The NeXTSTEP support uses the NeXTSTEP Berkeley Packet Filter
Ted Lemon's avatar
Ted Lemon committed
204 205
extension, which is not included in the base NextStep system.  You
must install this extension in order to get dhcpd or dhclient to work.
Ted Lemon's avatar
Ted Lemon committed
206

Ted Lemon's avatar
Ted Lemon committed
207 208
			       SUPPORT

Ted Lemon's avatar
Ted Lemon committed
209 210 211 212 213 214
The Internet Software Consortium DHCP server 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.
215 216 217

If you are going to use dhcpd, you should probably subscribe to the
dhcp-server and dhcp-announce mailing lists.  If you will be using
Ted Lemon's avatar
Ted Lemon committed
218 219 220 221 222 223 224 225 226 227 228
dhclient, you should subscribe to the dhcp-client mailing list.
PLEASE DO NOT send queries about non-isc clients to the dhcp-client
mailing list.   If you're asking about them on an ISC mailing list,
it's probably because you're using the ISC DHCP server, so ask there.

Please see http://www.fugue.com/dhcp/lists for details on how to
subscribe.  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.
229 230 231 232 233 234 235 236 237 238 239

PLEASE DO NOT SEND REQUESTS FOR SUPPORT DIRECTLY TO ME!  The number of
people using the DHCP Distribution 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.
Ted Lemon's avatar
Ted Lemon committed
240

Ted Lemon's avatar
Ted Lemon committed
241 242
				 BUGS

243 244 245 246 247
This release of the DHCP Distribution does not yet contain support for
DHCPINFORM.  Support for DHCPINFORM will be present in the release at
a later time.  DHCPINFORM is somewhat tangential to the main purpose
of the DHCP protocol, so this probably won't be a major problem for
most users.
Ted Lemon's avatar
Ted Lemon committed
248

249
Vendor tags and User tags are not currently supported.
Ted Lemon's avatar
Ted Lemon committed
250 251