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Date:      Sun, 1 Dec 1996 19:33:57 -0500 (EST)
From:      Rob Taylor <rtaylor@mpcs.com>
To:        freebsd-questions@freebsd.org
Message-ID:  <Pine.LNX.3.91.961201193317.21489A-100000@bbs.mpcs.com>

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Any help would be appreciated on this:

  I've been trying to track down a problem I'm having between quite a few 
computers and several BSD boxes.   The problem is mostly from NON-Unix 
based boxes (Windows NT, Windows 95, Windows 31, DOS packet stack) trying 
to go to a BSD based system.   

  In the interests of diagnosis we've tried tests in several ways.

 
  From Windows to BSD				- Bad
  From Linux to BSD				- Works
  From BSD to BSD				- Works
  From Win95 to BSD				- Bad
  From WinNT to BSD				- Bad

 We've tried it with several different Systems, and networking techniques 
(Slip/Ethernet/Different Cards/PPP) and the results are consistant. 

 Here's the problem.   Whenever a machine tries to pull large packets 
from the BSD box (MTU > 1024) it dies.  Those same clients can go to 
Linux, SunOS and any other OS other than BSD and work just fine.   
Generally the other operating systems will downsize the MTU to a working 
level.    At the end of this message I will include tcpdumps of working 
and non-working connections.  Also will include a sysctl dump of one of 
the systems in question.  I've tried playing with the sysctl values that 
have to do with networking, but to no avail.   All the systems which can 
not talk to the BSD systems can easily talk to any other OS without problem.
The problem is on our Web servers we have BSD (freebsd) and although I 
love the OS, I can't have it not work with some clients.   I'de like to 
stay with BSD but if I can not get it to work, I will need to switch to 
another OS.

  If anyone has had similar problems or knows of a bug fix, or even has 
an idea what the problem may be please email me.   The results are 
verifyable.  We have several BSD machines and its the same with all of them.
The software packages that have been tried on the clients (that do not 
work are) PC/TCP, Trumpet, Win95 32 bit stack, Trump32, and Netmanage.  
All with the same results.   


tcpdump of a BAD session with a BSD system:

17:59:35.405378 sys2.2222 > sys1.http: S 103427840:103427840(0) win 2048 <mss 1460> (ttl 255, id 415)
17:59:35.406051 sys1.http > sys2.2222: S 3781998081:3781998081(0) ack 103427841 win 17520 <mss 1460> (DF) (ttl 250, id 24112)
17:59:35.406952 sys2.2222 > sys1.http: . ack 1 win 2048 (ttl 255, id 416)
17:59:35.420935 sys2.2222 > sys1.http: P 1:284(283) ack 1 win 2048 (DF) (ttl 255, id 417)
17:59:35.426181 sys1.http > sys2.2222: P 1:257(256) ack 284 win 17520 (DF) (ttl 250, id 24113)
17:59:35.429415 sys1.http > sys2.2222: . 257:1717(1460) ack 284 win 17520 (DF) (ttl 250, id 24114)
17:59:35.648940 sys2.2222 > sys1.http: . ack 257 win 1792 (ttl 255, id 418)
17:59:36.831627 sys1.http > sys2.2222: . 257:1717(1460) ack 284 win 17520 (DF) (ttl 250, id 24121)
17:59:39.830035 sys1.http > sys2.2222: . 257:1717(1460) ack 284 win 17520 (DF) (ttl 250, id 24122)


TCPDUMP of a good session from the same client (sys2) with a Linux system 
(sys3):

18:00:47.323907 sys2.1111 > sys3.http: S 138686464:138686464(0) win 2048 <mss 1460> (ttl 255, id 422)
18:00:47.324715 sys3.http > sys2.1111: S 1140847812:1140847812(0) ack 138686465 win 14335 <mss 1436> (ttl 64, id 31299)
18:00:47.325478 sys2.1111 > sys3.http: . ack 1 win 2048 (ttl 255, id 423)
18:00:47.340212 sys2.1111 > sys3.http: P 1:301(300) ack 1 win 2048 (ttl 255, id 424)
18:00:47.341061 sys3.http > sys2.1111: . ack 301 win 14114 (ttl 64, id 31301)
18:00:47.564598 sys3.http > sys2.1111: P 1:320(319) ack 301 win 14335 (ttl 64, id 31307)
18:00:47.567620 sys3.http > sys2.1111: F 320:320(0) ack 301 win 14335 (ttl 64, id 31308)
18:00:47.568328 sys2.1111 > sys3.http: . ack 321 win 1729 (ttl 255, id 425)
18:00:47.571407 sys2.1111 > sys3.http: F 301:301(0) ack 321 win 1729 (ttl 255, id 426)
18:00:47.572211 sys3.http > sys2.1111: . ack 302 win 14334 (ttl 64, id 31309)


SYSCTL from one of the BSD systems (sys1):

kern.osrelease = 2.1.5-RELEASE
kern.osrevision = 199306
kern.version = FreeBSD 2.1.5-RELEASE #0: Sat Nov 23 17:09:58 EST 1996
kern.maxvnodes = 2257
kern.maxproc = 500
kern.maxfiles = 1000
kern.argmax = 65536
kern.securelevel = -1
kern.hostid = 0
kern.clockrate: hz = 100, tick = 10000, profhz = 1024, stathz = 128
kern.posix1version = 198808
kern.ngroups = 16
kern.job_control = 1
kern.saved_ids = 1
kern.boottime = Sun Nov 24 15:01:03 1996
kern.domainname = mpcs.com
kern.update = 30
kern.osreldate = 199607
kern.bootfile = /kernel
kern.maxfilesperproc = 1000
kern.maxprocperuid = 499
kern.dumpdev = disabled
kern.somaxconn = 128
kern.maxsockbuf = 262144
kern.ps_strings = -272637968
kern.usrstack = -272637952
kern.sockbuf_waste_factor = 8
vm.loadavg: 0.00 0.00 0.00
net.inet.ip.forwarding = 0
net.inet.ip.redirect = 1
net.inet.ip.ttl = 250
net.inet.ip.rtexpire = 93
net.inet.ip.rtminexpire = 10
net.inet.ip.rtmaxcache = 128
net.inet.ip.sourceroute = 0
net.inet.icmp.maskrepl = 0
net.inet.tcp.rfc1323 = 0
net.inet.tcp.rfc1644 = 0
net.inet.tcp.mssdflt = 512
net.inet.tcp.rttdflt = 15
net.inet.tcp.keepidle = 14400
net.inet.tcp.keepintvl = 150
net.inet.tcp.sendspace = 16384
net.inet.tcp.recvspace = 16384
net.inet.udp.checksum = 1
net.inet.udp.maxdgram = 9216
net.inet.udp.recvspace = 41600
hw.machine = i386
hw.model = i486DX
hw.ncpu = 1
hw.byteorder = 1234
hw.physmem = 32014336
hw.usermem = 26832896
hw.pagesize = 4096
hw.floatingpoint = 1
machdep.console_device = ??
machdep.adjkerntz = 18000
machdep.disable_rtc_set = 0
user.cs_path = /usr/bin:/bin:/usr/sbin:/sbin:
user.bc_base_max = 99
user.bc_dim_max = 2048
user.bc_scale_max = 99
user.bc_string_max = 1000
user.coll_weights_max = 0
user.expr_nest_max = 32
user.line_max = 2048
user.re_dup_max = 255
user.posix2_version = 199212
user.posix2_c_bind = 0
user.posix2_c_dev = 0
user.posix2_char_term = 0
user.posix2_fort_dev = 0
user.posix2_fort_run = 0
user.posix2_localedef = 0
user.posix2_sw_dev = 0
user.posix2_upe = 0
user.stream_max = 20
user.tzname_max = 255


- -- 
- -----------------------------------------------------------------------
Rob Taylor - Owner MPC Systems             VOICE:      (407)  727-9022
- ----------------------------------------+    FAX:      (407)  727-9022
 Is all that we see or seem...          |  EMAIL:     rtaylor@mpcs.com
 ...but a dream within a dream?  (EAP)  |    WEB:  http://www.mpcs.com
- ----------------------------------------+------------------------------
       MPC Systems * PO Box 275 * Melbourne, Fl * 32902-0275
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