OPNsense Forum

English Forums => General Discussion => Topic started by: marjohn56 on January 01, 2020, 04:35:11 pm

Title: Changing TTL of packets
Post by: marjohn56 on January 01, 2020, 04:35:11 pm

I ( and a few others ) have a need to be able to change the TTL of incoming packets on a specific interface. The reason for this is the Sky Q app. It appears that this app sends out an SSDP packet with a TTL of 1 to discover the existence of a Sky Q receiver on the same network, which is fine providing its on the same network, but if you use VLANs then even if you use something like PIMD to relay those packets across to the other VLAN(s) it will not get there due to the TTL.


Now it appears that you can do this with iptables on Linux but I'm yet to find a solution for FreeBSD, anyone have any ideas?

Title: Re: Changing TTL of packets
Post by: fabian on January 01, 2020, 04:48:23 pm

You may be able to solve the issue with a proxy and a quick google search brings up that one: https://gist.github.com/02strich/5504767

Title: Re: Changing TTL of packets
Post by: marjohn56 on January 02, 2020, 02:42:42 pm

I was thinking more along the lines of ng_patch... possible?

Title: Re: Changing TTL of packets
Post by: marjohn56 on January 03, 2020, 01:36:42 pm

I've got this working on a VM using my QNAP running Ubuntu and  using this Python script https://github.com/alsmith/multicast-relay (https://github.com/alsmith/multicast-relay)


So it's a solution for me..