>>>>> "Geoff" == Geoff Mulligan <geoff @
Geoff> Roderick Murchison, Jr. wrote:
>> We have a couple 2.4 machines lying around, and it looks like their max
>> tcp_conn_req_max value is only 32.
Geoff> yes. 2.4 had a maximum allowed value of 32 with a default of 5.
Not quite true. The kernel limit is actually higher, but ndd is forbidden
from raising it over 32. The following script (distributed with Spinner),
overcomes this artificial limitation.
Carson Gaspar -- carson @
edu carson @
<This is the boring business .sig - no outre sayings here>
# script to bump up tcp_conn_req_max > 32 in Solaris 2.4
# This script should be run by root and only by the competent who
# realize that this changes the kernel on the fly and its consequences
# READ THE FOLLOWING BEFORE USING THIS SCRIPT.
# Disclaimer:This is not an officially supported script from Sun
# Questions/comments about this script to mukesh .
# Warning ! This can affect the behavior of *all* TCP listeners on
# the machine. It has the potential to increase kernel memory useage.
# Since the the tcp_conn_req_max parameter is the limit
# the kernel imposes on the listeners, it is only relevant for listener
# applications which are compiled with the backlog parameter of the
# liten() call higher than the limit imposed by the kernel. The default
# limit is 5 in Solaris 2.4 and can be routinely bumped up as follows
# ndd -set tcp_conn_req_max <new limit upto 32>
# ndd imposes a max bound on how high this limit can be bumped up since
# it affects kernel memory resource useage and it is not wise to allow it
# to be increased to a dangerous level. This script is to allow experiments
# to increase it to higher values (The unreleased Solaris 2.5 increases
# this limit to 1024 and that should make this script obsolete).
# The exact value chosen should take into account the
# memory available on the machine and how many TCP listeners are likely
# to be affected by this. The known bound that people have been known
# to have experimented with is 128.
# This script operates by first bumping up the maximum imposed by ndd for
# this parameter using adb on the running kernel image and then using in
# a normal manner to set it to this value.
# To undo its affects, you can use adb to undo what is done here (left
# as an exercise to the reader :-)) or just reboot machine
echo "$*" 1>&2
echo "Aborting command" 1>&2
test "$1" = "uid=0(root)" || fail "You must be super user to run this script."
if [ $# -ne 1 ]; then
fail "Usage: $progname <limit in decimal>"
if [ $limit -gt 32 ]; then
adb -w -k /dev/ksyms /dev/mem << EOF 2>&1 >/dev/null
ndd -set /dev/tcp tcp_conn_req_max $limit