IP_TRANSPARENT

---

bind

--inet_bind
 +--inet_addr_valid_or_nonlocal

static inline bool inet_can_nonlocal_bind(struct net *net,
					  struct inet_sock *inet)
{
	return READ_ONCE(net->ipv4.sysctl_ip_nonlocal_bind) ||
		inet->freebind || inet->transparent;
}