How to change captive portal TTL value ???

arnav · Apr 10, 2020, 9:31 AM

Users connected to captive portal are sharing internet via bluetooth . I want to stop that sharing . As a solution i thought to change the TTL ..But m unable to find the way out to change the TTL. Is it possible in pfsense ?

Gertjan · Apr 10, 2020, 11:57 AM

Hi,

You want to 'reset' the TTL info in the coming-back traffic, initiated by the portal visitors, to 1, so it should be discarded by the next hop, or, the device acts as a router / shares the connection.
All returning packets have to be somehow mangled.
That would actually work I guess.

But first you have to write that stateful firewall, or modify an exiting one, that actually permits you to do so.

Look here, from 2005 : https://lists.freebsd.org/pipermail/freebsd-net/2005-April/007098.html

edit : pfSense, the captive portal, uses ipfw. All you need is that user-land program.