Feature #2966
closedvirtphy should have a localhost-only mode
100%
Description
I am using a virual-um setup on my laptop for osmocom development and testing without additional hardware.
In this situation I do not want virtphy's traffic leaking to the local network,
however the traffic currently leaks.
As a workaround, virtphy could be run in a separate network namespace or a virtual machine.
But this issue seeks a solution which works without resorting to a separate network stack.
Blocking the traffic with iptables leads to errors on virtphy's socket, and adding a route to 224/4 via lo does
not have the desired effect as multicast traffic is still routed towards the default route.
Possible solutions:
Harald suggested trying to set the TTL of multicast packets to 0, and there's also the IP_MULTICAST_IF socket option
which could be used to bind virtphy to a specific interface.
Updated by laforge about 4 years ago
- Assignee set to laforge
- % Done changed from 0 to 10
using osmo_sock_mcast_ttl_set(ofd->fd, 0)
prevents any of the multicast IP packets from being broadcast over the network. As an interesting side-effect, it also makes the GSMTAP IP not show up in any pcap capture anymore, neither on lo
, nor any
, nor the physical ethernet. The latter makes somewhat sense - but is of course not useful for debugging while operating real networks.
Updated by laforge about 4 years ago
- Status changed from New to In Progress
Patch in https://gerrit.osmocom.org/c/osmo-bts/+/17443 adds vty config option on BTS side to configure multicast TTL.
Updated by laforge about 3 years ago
- Status changed from In Progress to Resolved
- % Done changed from 10 to 100
patch has been merged more than a year ago.