OPNsense Forum

Archive => 19.7 Legacy Series => Topic started by: JasMan on January 06, 2020, 02:07:40 pm

Title: How to handle Multicasts with TTL=1?
Post by: JasMan on January 06, 2020, 02:07:40 pm

Hey,

I've seperated all my IoT devices into a single VLAN.
The associated Android management app of one of the IoT devices uses Multicasts to discover the device. Unfortunately the Multicast packets from the app have an TTL of 1. My mobile phone is in another VLAN and therefore the packets are discarted before PIMD can forward them to the IoT VLAN.

What would be the Best-Practise to handle this? Should I use iptable to mangle the TTL of the packets?

Jas

Title: Re: How to handle Multicasts with TTL=1?
Post by: marjohn56 on January 06, 2020, 04:03:37 pm

mangle is a Linux feature, not FreeBSD. See https://forum.opnsense.org/index.php?topic=15385.0 (https://forum.opnsense.org/index.php?topic=15385.0)

Title: Re: How to handle Multicasts with TTL=1?
Post by: JasMan on January 06, 2020, 04:39:08 pm

Quote from: marjohn56 on January 06, 2020, 04:03:37 pm

mangle is a Linux feature, not FreeBSD.

Ahh, good to know. I didn't know that.

Quote from: marjohn56 on January 06, 2020, 04:03:37 pm

See https://forum.opnsense.org/index.php?topic=15385.0 (https://forum.opnsense.org/index.php?topic=15385.0)

Yep, I already saw this thread but it doesn't work for the affected device. Because the TTL of the Multicast is 1, the packet is discarded before PIMD can handle it. The packets are not transmitted to the IoT VLAN.  :(

In my opinion I need to increase the TTL, or to tell OPNsense to ignore the TTL.

Title: Re: How to handle Multicasts with TTL=1?
Post by: marjohn56 on January 06, 2020, 05:01:46 pm

Read the last couple of messages in that thread. We are no longer using pimd.

Title: Re: How to handle Multicasts with TTL=1?
Post by: marjohn56 on January 06, 2020, 06:31:59 pm

I've just finished setting up Monit to start it at boot and restart it should it fail for any reason.


We are using Sky Q and the Sky Go app, the issue is TTL=1, this has sorted it and it's working well.