mirror of
https://github.com/Brandon-Rozek/website.git
synced 2024-09-19 06:05:14 -04:00
52 lines
No EOL
1.2 KiB
Markdown
52 lines
No EOL
1.2 KiB
Markdown
---
|
|
date: 2020-11-18 15:09:15
|
|
draft: false
|
|
medium_enabled: true
|
|
medium_post_id: 6f6efe549a47
|
|
tags:
|
|
- Linux
|
|
- Networking
|
|
title: Multicast Receive Script
|
|
---
|
|
|
|
I use `socat` to debug mutlicast traffic, though the syntax for it is complicated to learn. Here is the command that I normally use to debug multicast traffic.
|
|
|
|
```bash
|
|
socat UDP4-RECVFROM:"$port",ip-add-membership="$multicast_address":0.0.0.0,fork -
|
|
```
|
|
|
|
This says to:
|
|
|
|
- Listen to UDP traffic from `$port`.
|
|
- Subscribe to `$multicast_address`.
|
|
- `0.0.0.0` means to do it from the interface that matches the routing table for the multicast address.
|
|
- The rest makes it print the traffic to standard out.
|
|
|
|
To make life easier I created a little script called `mrecv` that takes a multicast address and port and forms the socat command for me.
|
|
|
|
```bash
|
|
#!/bin/bash
|
|
|
|
show_usage() {
|
|
echo "Usage: mrecv [multicast_address] [port]"
|
|
exit 1
|
|
}
|
|
|
|
contains_help_flag() {
|
|
if [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
|
|
return 0
|
|
fi
|
|
return 1
|
|
}
|
|
|
|
if [ "$#" -ne 2 ] ||
|
|
contains_help_flag "$1" ||
|
|
contains_help_flag "$2"; then
|
|
show_usage
|
|
fi
|
|
|
|
multicast_address="$1"
|
|
port="$2"
|
|
|
|
socat UDP4-RECVFROM:"$port",ip-add-membership="$multicast_address":0.0.0.0,fork -
|
|
``` |