The other day I updated the binaries on our pmax system to those
contained in arch/pmax/snapshot-1997-07-19.  I also compiled a new
kernel from the -current source (24Jul97).  When I booted this system
I started having this problem where anytime I was telnet'ed to the machine
and did something that generated a large (like 2 or 3 k) amount of
output the telnet connection hangs.  Other TCP based services
like ftp or nntp do not act like this, only telnet.  I tried recompiling
telnetd, libtelnet, libc, libutil, but the problem remains.

When a telnet connection gets hung it shows up in netstat like this:

Proto Recv-Q Send-Q  Local Address          Foreign Address        (state)
tcp        0   3097  lazy.CS.UNLV.EDU.telne duke.CS.UNLV.EDU.2376  ESTABLISHED


Any ideas as to what's going on here?  Is there some magic piece of the
system that I need to recompile?

On the off chance that it matters I've included the kernel config file for
the system:

#
# DECstation 5000/200
#
include		"arch/pmax/conf/std.pmax"

maxusers	64

options		MIPS1			# R2000/R3000 support (new)

# replaces "cpu ds5k/240"
#options	DS5000_240		# 3MAXPLUS (kn03) support
#options	DS5000_100		# 3MIN (kn02ba/kmin) support
#options	DS5000_25		# MAXINE (kn02ca/xine) support
options		DS5000_200		# 3MAX (kn02) support, one day

#options	DS3100			# PMAX (kn01) DECstation 2100, 3100


# Standard system options
#options	DIAGNOSTIC		# extra kernel debugging checks
#options	DEBUG			# extra kernel debugging support
options		"COMPAT_43"		# compatibility with 4.3BSD binaries
options		KTRACE			# system call tracing support
options		"NKMEMCLUSTERS=2048"	# (was 1024 4K pages in kernel malloc pool)
options		"NMBCLUSTERS=4096"	# default is 1024 for mb_map full error
options		"CCDNBUF=128"
options		"DFLDSIZ=209715200"	# 200meg datasize (news can get huge)

#options	KGDB			# support for kernel gdb
#options	"KGDBRATE=19200"	# kernel gdb port rate (default 9600)
#options	"KGDBDEV=15*256+0"	# device for kernel gdb

# Filesystem options
file-system	FFS		# fast filesystem with user and group quotas
#file-system	MFS		# memory-based filesystem
#file-system	KERNFS		# kernel data-structure filesystem
#file-system	FDESC			# user file descriptor filesystem
file-system	NULLFS		# null layer filesystem
file-system 	NFS		# Sun NFS-compatible filesystem (client)

# Networking options
options		NFSSERVER	# Sun NFS-compatible filesystem (server)
options		FIFO

options		INET		# Internet protocols
options		"TCP_COMPAT_42"	# compatibility with 4.2BSD TCP/IP
#options	GATEWAY		# IP packet forwarding
#options	MULTICAST	# Multicast support
#options	MROUTING	# Multicast routing support
#options	ISO		# OSI networking
#options	TPIP
#options	EON

options		COMPAT_10	# Pre-NetBSD 1.1 compatibility
options		COMPAT_11
options		COMPAT_12

# pmax specific
options		COMPAT_ULTRIX	# ultrix compatibility
options         EXEC_ECOFF      # Ultrix RISC binaries are ECOFF format
options		"HZ=256"	# RTC rate required

# Note that this configuration is unlikely to work, yet...
config		netbsd	root on ? type ?


include         "arch/pmax/conf/tc.std"

# ioasic standard baseboard options (5000/2x, 5000/1xx, 5000/2[46]0)
include         "arch/pmax/conf/builtin.ioasic"

# 5000/200-only (aka 3MAX aka KN02) baseboard devices.
# (KN02 has turbochannel but no IOASIC).
ioasic0         at      tc?
include         "arch/pmax/conf/builtin.3max"

########################################################################
# SCSI configuration                                                   #
########################################################################
#
# SCSI configuration for old DECstation SCSI driver
#
oldscsibus*	at asc?

include 	"arch/pmax/conf/scsi.pmax"

#
# pseudo-devices
#

pseudo-device	pty		64	# pseudo ptys
pseudo-device	bpfilter	8	# packet filter ports
pseudo-device	loop
pseudo-device	vnd		4	# virtual disk ick

#pseudo-device	ether			# From old config. what does it mean?
pseudo-device	rasterconsole	1 	# NB: raster console requires "fb"
pseudo-device	fb		3	# up to 3 framebuffers
pseudo-device  ccd     4               # concatenated disk devices
					--Greg