This is a command line utility and library written to test out multicast traffic flows on the network, and stress test the network and devices.
This utility is capable of entirely disrupting an L2 environment that isn't robustly configured, so caution is urged.
mcast is a command line utility capable of sending and recieving multicast or generic UDP traffic. It also allows simulation of IGMP joins, leaves, and querying.
NOTE: Currently developed and tested on Mac OSX 10.13.3 with Go version 1.10. The program should work on any Posix / Unix, but currently doesn't fully work on Windows. Superuser rights may be required for some functionality.
This repository is licenses under GPLv3. See LICENSE.md for details.
Copyright (C) 2018 Will Smith
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.
You must have go installed. If you don't, or you're not sure, visit https://golang.org/doc/install. You must also be running a supported and tested OS and Go version.
Install program with
go install github.com/individuwill/mcast
Or alternatively download pre-built binaries from releases v0.1
Run the receiver on one computer
mcast receive
Run the sender on another computer
mcast send
Multicast routing must be enable between hosts
mcast is driven by subcommands. You invoke mcast like:
mcast subcommand [-options...]
The list of subcommands are:
- help
- send
- receive
- join
- leave
- query
Each subcommand then has a set of options to control its behavior. Many of the commands share similar options, and the option syntax is the same when this is the case. Below is a detailed explanation of each subcommand and its associated options.
Display help and usage message for the application
mcast help [command]
Help for a specific subcommand can be shown by specifying the command you want help with.
Will send UDP traffic to the IP address specified. Will send continuously in a loop at specified interval until the program is terminated or max number of messages are sent.
mcast send [-options...]
The options are:
- -group : IP destination address. Can use CIDR notation to send to multiple addresses.
- default : 239.1.1.5
- -port : Destination UDP port
- default : 5050
- -interface-ip : Interface to use defined by IP addrress. Must be in 0.0.0.0:0000 format. Default allows system to decide.
- -ttl : IP ttl (time to live)
- default : 50
- -tos : TOS / DSCP to be set. Only works on unicast addresses. 0xB8 for voice.
- default : 0
- -text : Text / data to send to the receiver. Use '{c}' to access counter
- default : This is test number: {c}
- -padding : Length to pad the message. Will make message take up specified number of bytes.
- default : 0
- -interval : Interval between sending messages (milliseconds).
- default : 1000
- -start-value : Non-negative start value message incrementer / counter
- default : 1
- -max : Number of packets to send. '0' for continuous send
- default : 0
Will listen to UDP traffic on the IP address specified and print out the text content of the received UDP messages if the option is enabled.
mcast receive [-options...]
The options are:
- -group : IP multicast destination address. Can use CIDR notation to listen to multiple multicast address.
- default : 239.1.1.5
- -port : Listen UDP port
- default : 5050
- -interface : Interface name to listen on. Default allows system to decide.
- -show : Print the text contained in the received UDP message.
- default : true
Not implemented yet
Not implemented yet
Not implemented yet
Some basic code tests are currently present in the repository, but much more extensive coverage is needed.
You can manually execute the tests with 1 of the following commands:
go test ./..
go test github.com/individuwill/mcast
go test github.com/individuwill/mcast/multicast
There is a Jenkins file in the root of the repository for automatically running the tests, cross-compiling for 3 operating systems, and creating a zip artifact. There is a git-hook in the repo that runs this on-commit, and it will mark the commit as pass or fail.
The plan is to test the code on the 3 operating systems, and test the interaction between sending and receiving multicast in the jenkins cluster.
There is also a plan to automatically create a new release with binaries when a new tagged commit to master is made and it passes the tests.
Currently only the code tests are executed. They are executed in a linux environment through the official golang docker container. The binaries are stored in Jenkins, and manual releases must be made.
I wrote this program to test multicast functionality in my network designs as I found existing tooling for testing multicast lacking. I needed a small portable binary that I could copy to any host for quick testing. This is especially useful for virtual lab environments.
I also had a need to test and be able to observe traffic behavior in wireless networks to understand vendor configuration options that lead to the most robust multicast configuration for a wireless environment. To this point, with the correct set of options with this program, a single host can cause a DoS to an entire wireless segment if the wireless infrastructure isn't properly configured or the vendor does not provide the ability to configure or control multicast behavior.
I took the opportunity to use this program to learn more about multicast and do some coding in Golang.
I used the https://github.com/troglobit/mtools suite for initial testing of the program while developing it. That toolset was also inspiration for mcast. I chose not to extend mtools as I wanted easy concurrency and easy cross compiling and cross platform binaries.
Here are some other tools I use or used for testing multicast functionality
