Ban lists: where Guard and fail2ban ban addresses

A program bans an address (every port, or a protocol's ports) for a
time; the ban list says what it is kept from: the firewall, some hosts
behind it, or everything. Bans drop ahead of every rule, close the
address's connections, group IPv6 by /64, are kept in the database
across restarts and audited. Never banned: the inside, the firewall's
own addresses, the caller, the list's never. bans grant (bans:write:LIST),
hc banlist/bans/ban/unban, Traffic -> Bans, a fail2ban action in contrib/,
and failed logins and refused tokens logged for Guard and fail2ban.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/render/render.go

@@ -50,6 +50,8 @@ type Options struct {
 	// DeviceSets are the per-device traffic counters' entries
 	// (stats_up_v4 …), so a reload keeps them.
 	DeviceSets map[string][]Element
+	// Bans are the ban lists' active bans, added to their sets.
+	Bans []Ban
 	// Shadow renders for shadow mode: nothing is blocked, rejected,
 	// translated or changed (see the package comment).
 	Shadow bool
@@ -137,6 +139,7 @@ func (r *renderer) render() {
 	w.emit("", "delete table inet %s", Table)
 	w.emit("", "table inet %s {", Table)
 	r.sets()
+	r.banSets()
 	r.deviceSets()
 	devices := r.flowtableDevices()
 	if len(devices) > 0 {
@@ -165,6 +168,7 @@ func (r *renderer) render() {
 	w.line = base + chains.line
 	w.emit("", "}")
 	r.elements()
+	r.banElements()
 }
 
 // ---- sets
@@ -382,6 +386,7 @@ func (r *renderer) input() {
 	if b.Loopback {
 		r.builtin("loopback", "iifname \"lo\" accept")
 	}
+	r.banRules(model.ChainInput)
 	// Rules that count traffic see every packet: before the established
 	// connections are accepted.
 	r.rules(model.ChainInput, true)
@@ -411,6 +416,7 @@ func (r *renderer) forward(flowtable bool) {
 	st := r.st
 	b := st.Settings.Builtins
 	r.chain("forward", "forward", "filter", st.Settings.ForwardPolicy)
+	r.banRules(model.ChainForward)
 	ext := st.ExternalInterfaces()
 	// Shadow mode changes no packet.
 	if b.MSSClamp && len(ext) > 0 && !r.opt.Shadow {