Suggestion: DNS Forwarding Only mode

[phantomcraft]

It's just a suggestion, I don't know if you'll find this relevant, but...

When using privileged containers a transparent forwarder with iptables rules is preferable as its faster, but many transparent forwarders don't provide DNS forwarding that's need for the NATed sandbox, so this feature would be useful.

Something like:

$ slirp4netns --dns-fw 172.16.0.1:10053
$ iptables -t nat -A PREROUTING -i some-veth -p udp -m udp -d 172.16.0.1 --dport 53 -j DNAT --to-destination 172.16.0.1:10053