3 ms·
Not quite. Yes, that may be true for ping, but ping is very much special. It builds its raw packets. But do a "strace -econnect nc 0 22" and you'll see that ye
by knorker 6y ago
Not quite. Yes, that may be true for ping, but ping is very much special. It builds its raw packets.
But do a "strace -econnect nc 0 22" and you'll see that yes, actually, a connect() syscall to "0.0.0.0" does connect to localhost.
- firethief 6y agoInteresting. That doesn't seem to be specified in the RFC1122 standard or the Linux ip(7) docs, but it's an explicit special case in the kernel (ip_route_output_key_hash_rcu): if (!fl4->daddr) { fl4->daddr = fl4->saddr; if (!fl4->daddr) fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK); ...