On systems with Docker or other container runtimes, the ICMP proxy was
selecting virtual bridge interfaces (br-*, docker*, veth*) instead of
physical interfaces (eth*, enp*, ens*, wlan*).
This change:
- Adds interface filtering to exclude known virtual/bridge interfaces
- Prioritizes physical interfaces when selecting ICMP source addresses
- Changes fallback dial target from 192.168.0.1 to 8.8.8.8 for better
default route detection
- Applies the same filtering to IPv6 source selection
The existing --icmpv4-src and --icmpv6-src flags continue to work as
manual overrides.
Fixes#1546
0b90c422c4