Linux built-in or open source program to join multicast group?

Question

I'm using tcpdump to capture multicast packets and had to code up a custom program to join multicast feeds so tcpdump will "see" the packets. Just wondering if netcat or any other applications can perform this function instead?

Answer 1

You can do this using the ip maddr add command.

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SYNTAX

ip maddr [ add | del ] MULTIADDR dev STRING 

DESCRIPTION

It attaches/detaches a static link layer multicast address to listen on the interface. Note that it is impossible to join protocol multicast groups statically. This command only manages link layer addresses.

address LLADDRESS (default)
    the link layer multicast address. 
dev NAME
    the device to join/leave this multicast address. 

EXAMPLES

Example for a wired connection:

ip maddr add ff02::fb dev eth0

Example for a wireless connection:

ip maddr add 224.0.0.251 dev wlan0