3 ms·

What you say is only true if your firewall is configured to do so. By default (without any firewall), all traffic is exposed to every interface I believe. EDIT

• aaronmdjones 3y ago
  This is not correct. Binding a socket to localhost (UDP, or TCP listener, or SCTP listener, ...) will prevent traffic from other network interfaces using it, even on the same machine. virtus ~ # nft list ruleset virtus ~ # nc -vvv -l -s 127.0.0.1 -p 1234 Listening on localhost 1234 virtus ~ # ip -4 addr show scope global dev enp3s0 2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000 inet 10.20.1.75/24 brd 10.20.1.255 scope global enp3s0 valid_lft forever preferred_lft forever virtus ~ # nc -vvv 10.20.1.75 1234 nc: connect to 10.20.1.75 port 1234 (tcp) failed: Connection refused The security consideration with binding to localhost is that every process in the same network namespace can connect to that socket, regardless of what user the process is running as, unless you use netfilter to isolate what users can connect to where. Even then any process running as the given user will be permitted. A UNIX domain socket bound to a filesystem path can be constrained by filesystem ACLs and chroots, without having to touch netfilter at all.