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pSOSystem System Calls - Read

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pNA+ <strong>System</strong> <strong>Calls</strong> ioctl<br />

default TTL value may be accessed by the IP group MIB commands<br />

SIOCGIPDEFAULTTTL and SIOCSIPDEFAULTTTL.<br />

ICMP and Raw IP packets are assigned a fixed default TTL value for 255. This<br />

system wide default TTL value cannot be changed.<br />

For UDP/IP multicast packets the default TTL value is defined to be 1 but may be<br />

modified using the setsockopt() call.<br />

The following operations are available to change the TTL value on a per socket/<br />

connection basis. Initially the per socket TTL is set as per the rules above. The TTL<br />

value may be changed for each socket. To set or get the IP TTL value the arg<br />

parameter must point to an integer. The TTL value must be non-negative.<br />

Operation Description<br />

SIOCSIPTTL Sets the IP TTL value of the socket.<br />

SIOCGIPTTL Gets the IP TTL value of the socket.<br />

UDP Checksum Operations<br />

The following operations may be used to access or modify the UDP checksum<br />

computation policy. By default, UDP checksum is not computed for outgoing UDP<br />

packets. The arg parameter must point to an integer. The integer is set to 1 to<br />

enable UDP checksum computation or 0 to disable the computation.<br />

Operation Description<br />

SIOCSUDPCHKSUM Sets the UDP checksum computation flag.<br />

SIOCGUDPCHKSUM Gets the UDP checksum computation flag.<br />

MIB-II Related Operations<br />

The ioctl() call is used to access pNA+ MIB-II objects, defined in this subsection.<br />

Refer to <strong>pSO<strong>System</strong></strong> <strong>System</strong> Concepts for more details on set and get operations.<br />

The operations described in the remainder of the ioctl() call description are<br />

defined by symbolic constants in :<br />

<strong>pSO<strong>System</strong></strong> <strong>System</strong> <strong>Calls</strong> 4-29<br />

4

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