sysctl

Get or set the state of the socket manager

Syntax:

sysctl [-n] name...

sysctl [-n] -w name=value...

sysctl [-n] -a|A

Options:

-a

List all the currently available string or integer values.

-A

List all the known MIB names including tables. Those with string or integer values are be printed with the -a flag; for the table values, the name of the utility to retrieve them is given.

-n

Suppress the printing of the field name and output only its value. This flag is also used for setting shell variables. For example, to save the IP TTL value in the variable ipttl:

set ipttl=`sysctl -n net.inet.ip.ttl`
      

-w

If just a MIB style name is given, the corresponding value is retrieved. To set a value specify: this flag, the MIB name followed by an equal sign, and the new value to be used.

Description:

The sysctl utility retrieves the state of the socket manager and allows processes with appropriate privilege to set the state. The state to be retrieved or set is described using a Management Information Base (MIB) stylename, described as a dotted set of components.

The information available from sysctl consists of integers and tables. The tabular information can only be retrieved by special purpose programs such as netstat and arp. The integer information is summarized below. For a detailed description of these variable see sysctl(). The changeable column indicates whether a process with appropriate privilege can change the value.

Examples:

Check to see if the UDP checksum is enabled:

sysctl net.inet.udp.checksum

Enable IP forwarding so that the host acts as a router:

sysctl -w net.inet.ip.forwarding=1

See also:

netstat

sysctl() in the Library Reference