Jump to content United States-English
HP.com Home Products and Services Support and Drivers Solutions How to Buy
» Contact HP
More options
HP.com home
HP-UX Reference > N


HP-UX 11i Version 3: February 2007

Technical documentation

» Feedback
Content starts here

 » Table of Contents

 » Index


ndd — network tuning


ndd -get network_device parameter

ndd -set network_device parameter value

ndd -h sup[ported]

ndd -h unsup[ported]

ndd -h [parameter]

ndd -c


The ndd command allows the examination and modification of several tunable parameters that affect networking operation and behavior. It accepts arguments on the command line or may be run interactively.

The -h option displays all the supported and unsupported tunable parameters that ndd provides in the following categories: ARP, IP, IPSEC, IPV6, IPV6 Neighbor Discovery (ND), RAWIP, RAWIP6, SOCKET, TCP, and UDP.

The tunable parameters in each category may be accessed with the proper valid network_device name. The network_device name is referred to as TRANSPORT_NAME[] in /etc/rc.config.d/nddconf.

The valid network_device names (and their associated parameter categories) are:




(IP and IPSEC),


(IPV6, IPV6 Neighbor Discovery, and IPSEC v6),








(TCP), and



Set parameter to ? to get a list of parameters for a particular network_device.

ndd -get

Get the value of the parameter for network_device and print the value to standard output. Returned numbers are always displayed as decimal strings.

ndd -set

Set parameter for network_device to value.

All times are specified in milliseconds; for example, 240000 for 4 minutes. Unless stated otherwise, numbers are assumed to be in decimal. Use "0x" prefix to specify hexadecimal values.

In general, all tunable parameters are global; in other words, they affect all instances of the network module. Some settings take effect immediately, while others are used to initialize data for an instance and will only affect newly opened streams.

ndd -h supported

Display all the supported tunable parameters. This set of parameters are supported by HP and detailed descriptions of these tunable parameters are available through the -h parameter command.

ndd -h unsupported

Display all the unsupported tunable parameters. This set of parameters are not supported by HP and modification of these tunable parameters are not suggested nor recommended. Setting any unsupported tunable parameters on your system may result in adverse effects to your networking operations.

ndd -h

When parameter is specified, a detail description of the parameter, along with its minimum, maximum, and default value are displayed. If no parameter is specified, it displays all supported and unsupported tunable parameters.

ndd -c

Read input from the configuration file /etc/rc.config.d/nddconf and set the tunable parameters. A user may specify tunable parameters in the nddconf configuration file, and these parameters will be set automatically each time the system boots.


When the command fails, an error message is printed to the standard error and the command terminates with an exit value of one.


Care must be used when setting parameters for a network_device. Setting a tunable parameter to an inappropriate value can result in adverse affects to your networking operations.


To get help information on all supported tunable parameters:

ndd -h supported

To get a detail description of the tunable parameter, ip_forwarding:

ndd -h ip_forwarding

To get a list of all TCP related parameters:

ndd -get /dev/tcp ?

To get the current value of the tunable parameter, ip_forwarding:

ndd -get /dev/ip ip_forwarding

To set the value of the default TTL parameter for UDP to 128:

ndd -set /dev/udp udp_def_ttl 128



Contains tunable parameters that will be set automatically each time the system boots.


ndd was developed by HP.

Printable version
Privacy statement Using this site means you accept its terms Feedback to webmaster
© 1983-2007 Hewlett-Packard Development Company, L.P.