[3735] in linux-net channel archive
Linux DHCP servers
daemon@ATHENA.MIT.EDU (Mark Fernandes)
Wed Jul 17 03:47:24 1996
Date: Mon, 15 Jul 96 10:59:47 -0700
From: Mark Fernandes <fizban@apple.com>
To: <net-patches@lxorguk.ukuu.org.uk>, <linux-net@vger.rutgers.edu>,
<lenehan@cs.latrobe.edu.au>, <JBRUNI@autobaun.com>
--Emailer_-1374240707
Content-Type: text/plain; charset="US-ASCII"
Hello,
The following issue was originally sent to Apple Developer Technical
Support. It was thought to have been a problem with OpenTransport, but
upon further investigation it was decided that the issue lies with Linux.
We would like to resolve this issue and ask your help in doing so. At a
minimum we would ask that you send us an acknowledgement that you have
received this report. We would also ask that, if it's possible, you send
any information you can as to a resolution of this issue, e.g. that
you're working on it, have a fix, aren't going to fix it, etc.
Please let us know if there is any further information we can provide to
help you resolve this issue. If your testing indicate that the problem
might be ours, send it back to us with your test results so we can do
further testing to isolate the cause.
Network traces tests with OpenTransport 1.1.1b4 are available in the
enclosed folder labeled ExtraInfo. The enclosure is SelfExtracting and
binhexed.
Myself and the originator of the problem would greatly appreciate being
added to the mailing list for correspondences related to this issue.
Regards,
Mark Fernandes
fizban@apple.com
Developer Technical Support
Apple Computer, Inc.
originator: JBRUNI@AUTOBAUN.COM
----------------------------------------------------------------
Bug ID # 1353121
** TITLE: DHCP seems not to like the way Linux has implemented the DHCP
server
Developer States:
I think I may have found a bug in OT's DHCP. DHCP seems not to like the
way Linux has
implemented the DHCP server, because OT crashes whenever I try to use it.
We have a Linux system running as our DNS and DHCP server (among other
things).
If I select DHCP in the TCP/IP control panel and then launch a TCP
application
such as Fetch or NCSA Telnet, my Mac locks up. After OT lets go of the
system,
I can see that the correct information has been filled out in the TCP/IP
control panel but doing anything with any TCP application causes the Mac
to
freeze completely. Even trying to restart from the Finder causes it to
hang.
BootP, however, works fine.
Our resident unix-head admits that Linux probably
got the DHCP server wrong, since you have tested your DHCP implementation
against SunOS and other real versions of Unix; but, I have a problem
with OT
crashing my computer just because a server fed it bad information.
There is one thing wrong in the BootP. We have two internal DNS servers,
and the BootP
server is giving out the IP addresses for both of them. However, OT only
seems
to be understanding the first (primary), and it doesn't get the
secondary.
The unix-head mentioned something about OT's UDP packet size being too
small
and so it isn't getting the rest of the data. I'm not sure how valid this
information is, however.
Here are the versions I'm using:
OT 1.1
Debian
Linux 1.1
Fetch 3.0.1
NCSA Telnet 2.6
** CONFIGURATION:
May 24 1996 4:52PM
Quadra 610, 16M RAM
PM 6100/66, 24M RAM
PM 9500/120, 24M RAM
All were running
System 7.5.3 with OT 1.1.
** DIAGNOSIS:
May 28 1996 10:25AM
OT understands and
configures all DNS server addresses returned by the DHCP server.
However, it
only displays in the TCP/IP control panel the first one. This will be
changed
in a later version of OT.
(The same thing happens with default routers
returned by the DHCP server - OT currently displays only the first.)
I would also like to know what the developer means by "...After OT lets
go of the
system..." - to me, that sounds like a hang, not a crash, and might be
seen as
reinforcement of my suspicions about the IP address lease interval.
Please see if the developer can get this information for me. Any kind of
packet trace
would be useful, but EtherPeek would be best.
Jun 10 1996 2:10PM
Additional Developer Info:
I've run another test with OT 1.1.1b4 and the
results with DHCP are
pretty much the same as 1.1. However, the behavior
seems to be slightly
different.
I'll try to describe the behavior I'm
finding in more descriptive terms.
I set TCP/IP to use the DHCP in the
Configure popup menu. TCP/IP is set
to load only when needed. I launch NCSA
Telnet 2.6 to cause TCP/IP to
load and the machine freezes for about 30
seconds. After which I can use
the machine again.
However, the TCP/IP stack
is dead in that no internet program can do
anything. When I try to telnet
into a host, I'm unable to resolve names.
Entering the IP address directly
doesn't work either. In addition to NCSA
Telnet, I tried doing the same
thing with Cyberdog. Again, no luck,
Cyberdog is unable to resolve names.
With OT 1.1.1, I'm able to restart my machine cleanly. When I was using
OT 1.1, I was unable to restart my machine from the Finder because it
would freeze after choosing "Restart". When I switch back to BootP,
everything works fine.
Jun 10 1996 4:39PM
Thanks for the packet trace.
As I suspected, the problem is that no IP address
lease interval is provided. According to RFCs 1531 and 1541 (the first
and
current DHCP specifications), an IP address lease interval MUST
(emphasis from
the RFC) be provided in the Options field of every DHCPACK packet - the
message from the server that actually grants the lease. The Linux DHCP
server
does not include that option (hex 33, decimal 51).
Because no lease interval
was provided, OT's code winds up believing that the interval is zero.
OT's
DHCP client then generates a lease renewal interval, which, if not
explicitly
provided by the DHCP server, is half of the lease interval (still zero).
As
the packet trace shows, OT then attempts to renew the lease (the second
DHCPREQUEST). Eventually the renewal effort times out, the lease interval
itself times out (still zero), and OT unloads the TCP/IP stack. Result:
exactly what the developer sees - no network traffic.
If the Linux DHCP
server wants to assign an IP address lease that is of unlimited
duration, it
must do so explicitly by specifying a lease interval of 0xFFFFFFFF
(minus-1).
Otherwise, it must specifiy a nonzero lease interval in seconds; the
smallest
compliant interval is 1 hour.
Please return as a third-party problem (Linux).
--Emailer_-1374240707
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