Relay multicast packets between interfaces
Useful, for example, if you have Sonos speakers on one interface, or VLAN, and you want to be able to control them from devices on a different interface/VLAN. Similar for Chromecast devices.
By default, SSDP multicast packets received on 239.255.255.250:1900 are relayed to the other interfaces listed, as well as multicast DNS packets received on 224.0.0.251:5353.
Please note that even when your devices have discovered one another, at least in the Sonos case, a unicast connection will be established from the speakers back to the controlling-telephone. You will need to make sure that IP forwarding is enabled (echo 1 > /proc/sys/net/ipv4/ip_forward) and that no firewalling is in place that would prevent connections being established.
usage: multicast-relay.py [-h] --interfaces INTERFACE INTERFACE [INTERFACE ...] [--relay MULTICAST:PORT [MULTICAST:PORT ...]] [--noMDNS] [--noSSDP] [--wait] [--foreground] [--verbose]
--interfaces specifies the >= 2 interfaces that you desire to listen to and relay between.
--relay specifies additional multicast addresses to relay.
--noMDNS disables mDNS relaying.
--noSSDP disables SSDP relaying.
--wait indicates that the relay should wait for an IPv4 address to be assigned to each interface rather than bailing immediately if an interface is yet to be assigned an address.
--foreground stops the process forking itself off into the background. This flag also encourages logging to stdout as well as to the syslog.
--verbose steps up the logging.
multicast-relay.py requires the python 'netifaces' package. Install via 'easy_install netifaces' or 'pip install netifaces'. For ZeroShell users, please review README-ZeroShell for further instructions.
Al Smith ajs@aeschi.eu