mtools

This is a cleaned up version of mtools from the University of Virginia's Multimedia Networks Group, with added IPv6 support.

The tools msend and mreceive can be particulary useful when debugging multicast setups.

Remember, when routing multicast, always check the TTL!

NAME

• msend - send UDP messages to a multicast group
• mreceive - receive UDP multicast messages and display them

SYNOPSIS

msend [-46hnv] [-g GROUP] [-p PORT] [-join] [-t TTL] [-i ADDRESS] [-P PERIOD]
      [-I INTERFACE] [-c NUM] [-text "text"]
mreceive [-46hnv] [-g group] [-p port] [-i ip] ... [-i ip] [-I INTERFACE]

DESCRIPTION

msend continuously sends UDP packets to the multicast group specified by the -g and -p options.

mreceive joins a multicast group specified by the -g and -p options, then receives and displays the multicast packets sent to this group:port combination by the msend command.

OPTIONS

• -4

  Select IPv4 test group, use with -I when not using -i or any group. This is the default. See -6 for an example.

• -6

  Select IPv6 test group, use with -I when not using -i or any group. Example:

    $ msend -6 -I eth0
    Now sending to multicast group: ff2e::1
    Sending msg 1, TTL 1, to ff2e::1:4444:
    ...
  

• -c NUM

  Number of packets to send, default: unlimited.

• -g GROUP

  Specify the IP multicast group address to which packets are sent, or received. The default group is 224.1.1.1 for IPv4 and ff2e::1 for IPv6.

• -p PORT

  Specify the UDP port number used by the multicast group. The default port number is 4444.

• -join

  Multicast sender will join join the multicast group. By default, a multicast sender does not join the group.

• -t TTL

  Specify the TTL (1-255) value in the message sent by msend. You must increase this if you want to route the traffic, otherwise the first router will drop the packets! The default value is 1.

• -i ADDRESS

  Specify the IP address of the interface to be used to send the packets. For mreceive one or more interfaces can be given. The default value is INADDR_ANY which implies that the default interface selected by the system will be used.

• -I INTERFACE

  Specify the interface to send on. Can be specified as an alternative to -i.

• -P PERIOD

  Specify the interval in milliseconds between two transmitted packets. The default value is 1000 milliseconds.

• -q

  Quiet mode, don't print sending or receiving messages. Errors are still printed.

• -text "text"

  Specify a message text which is sent as the payload of the packets and is displayed by the mreceive(8) command. The default value is an empty string.

• -n

  Interpret the contents of the message text as a number instead of a string of characters. Use mreceive -n on the other end to interpret the message text correctly.

• -v

  Print version information.

• -h

  Print the command usage.

BUILD & INSTALL

The build system is a plain Makefile with the following environment variables to control the build and install process:

• CC: possible to override default compiler, alt. to CROSS
• CROSS: set when cross compiling, e.g. CROSS=aarch64-linux-gnu-
• prefix: install prefix, default /usr/local

Example:

$ make all
$ make install prefix=/usr