A unicast DHCP renewal reply currently reaches dhcpcd only by matching
the firewall's ESTABLISHED,RELATED conntrack rule against the outbound
request. When that conntrack entry has already expired the reply is
dropped silently, with no log line anywhere. The client's broadcast
paths (DISCOVER, rebind) bypass netfilter entirely via a raw BPF
socket and never depend on this state — only the unicast renewal path
does.
This removes that dependency by accepting DHCP client traffic
unconditionally, gated on the firewall being enabled at all. It does
not identify or claim to fix the cause of any particular observed
renewal failure.
Refs #3389
c3f5479ca8