NAME

Linux::SocketFilter - interface to Linux's socket packet filtering

DESCRIPTION

This module contains the constants and structure definitions to use Linux's socket packet filtering mechanism.

CONSTANTS

The following constants are exported:

Socket Options

 SO_ATTACH_FILTER SO_DETACH_FILTER

BPF Instructions

 BPF_LD BPF_LDX BPF_ST BPF_STX BPF_ALU BPF_JMP BPF_RET BPF_MISC
 BPF_W BPF_H BPF_B BPF_IMM BPF_ABS BPF_IND BPF_MEM PBF_LEN BPF_MSH
 BPF_ADD BPF_SUB BPF_MUL BPF_DIV BPF_OR BPF_AND BPF_LSH BPF_RSH BPF_NEG
 BPF_JA BPF_JEQ BPF_JGT BPF_JGE BPF_JSET
 BPF_K BPF_X BPF_A BPF_TAX BPF_TXA

This entire set of constants is also exported under the tag name :bpf.

Linux BPF Extension Packet Addresses

 SKF_AD_OFF SKF_AD_PROTOCOL SKF_AD_PKTTYPE SKF_AD_IFINDEX
 SKF_NET_OFF SKF_LL_OFF

STRUCTURE FUNCTIONS

$buffer = pack_sock_filter( $code, $jt, $jf, $k )

( $code, $jt, $jf, $k ) = unpack_sock_filter( $buffer )

Pack or unpack a single BPF instruction.

SOCKET FUNCTIONS

attach_filter( $sock, $filter )

Attaches the given filter program to the given socket. The program should be a string formed by concatenating multiple calls to pack_sock_filter() to build the filter program.

detach_filter( $sock )

Detaches the current filter from the socket, returning it to accepting all packets.

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>