HP-UX HB v13.00 Ch-09 - Networking Basics
HP-UX Handbook – Rev 13.00 Page 21 (of 27)
Chapter 09 Network Basics
October 29, 2013
Kernel configuration with ndd
HP-UX gives us lots of opportunities to tune the network stack for performance improvement
and adaptation to different environments. The behavior of the kernel can be changed with the
ndd command.
# ndd –h
This will show you the available kernel parameters. You will get additional information for each
parameter, if you run the command with the option “-h” and the specific parameter, e.g.
# ndd -h ip_ire_gw_probe
Enable dead gateway probes. This option should only be disabled on networks containing
gateways which do not respond to ICMP echo requests (ping).
[0-1] Default: 1 (probe for dead gateways)
The command:
# ndd –get /dev/<device> <parameter>
will show you the current value of the parameter and you can change it with:
# ndd –set /dev/<device> <parameter> <value>
We can deduce the device that we have to use, by looking at the first part of the parameter
names. For example:
# ndd –get /dev/ip ip_ire_gw_probe
1
# ndd –get /dev/tcp tcp_fin_wait_2_timeout
0
Please be aware, that changes done with ndd, will only be done in the running kernel (in
memory) and will not survive a reboot. To make those changes permanent, you should use the
file /etc/rc.config.d/nddconf. For each parameter you have to add three lines – like this:
TRANSPORT_NAME[0]=<device>