[client, management] Add port forwarding (#3275)

Add initial support to ingress ports on the client code.

- new types where added
- new protocol messages and controller

client/firewall/iptables/acl_linux.go

@@ -30,10 +30,8 @@ type entry struct {
 }
 
 type aclManager struct {
-	iptablesClient     *iptables.IPTables
-	wgIface            iFaceMapper
-	routingFwChainName string
-
+	iptablesClient  *iptables.IPTables
+	wgIface         iFaceMapper
 	entries         aclEntries
 	optionalEntries map[string][]entry
 	ipsetStore      *ipsetStore
@@ -41,12 +39,10 @@ type aclManager struct {
 	stateManager *statemanager.Manager
 }
 
-func newAclManager(iptablesClient *iptables.IPTables, wgIface iFaceMapper, routingFwChainName string) (*aclManager, error) {
+func newAclManager(iptablesClient *iptables.IPTables, wgIface iFaceMapper) (*aclManager, error) {
 	m := &aclManager{
-		iptablesClient:     iptablesClient,
-		wgIface:            wgIface,
-		routingFwChainName: routingFwChainName,
-
+		iptablesClient:  iptablesClient,
+		wgIface:         wgIface,
 		entries:         make(map[string][][]string),
 		optionalEntries: make(map[string][]entry),
 		ipsetStore:      newIpsetStore(),
@@ -314,9 +310,12 @@ func (m *aclManager) seedInitialEntries() {
 	m.appendToEntries("INPUT", []string{"-i", m.wgIface.Name(), "-j", chainNameInputRules})
 	m.appendToEntries("INPUT", append([]string{"-i", m.wgIface.Name()}, established...))
 
+	// Inbound is handled by our ACLs, the rest is dropped.
+	// For outbound we respect the FORWARD policy. However, we need to allow established/related traffic for inbound rules.
 	m.appendToEntries("FORWARD", []string{"-i", m.wgIface.Name(), "-j", "DROP"})
-	m.appendToEntries("FORWARD", []string{"-i", m.wgIface.Name(), "-j", m.routingFwChainName})
-	m.appendToEntries("FORWARD", append([]string{"-o", m.wgIface.Name()}, established...))
+
+	m.appendToEntries("FORWARD", []string{"-o", m.wgIface.Name(), "-j", chainRTFWDOUT})
+	m.appendToEntries("FORWARD", []string{"-i", m.wgIface.Name(), "-j", chainRTFWDIN})
 }
 
 func (m *aclManager) seedInitialOptionalEntries() {

client/firewall/iptables/manager_linux.go

@@ -52,7 +52,7 @@ func Create(wgIface iFaceMapper) (*Manager, error) {
 		return nil, fmt.Errorf("create router: %w", err)
 	}
 
-	m.aclMgr, err = newAclManager(iptablesClient, wgIface, chainRTFWD)
+	m.aclMgr, err = newAclManager(iptablesClient, wgIface)
 	if err != nil {
 		return nil, fmt.Errorf("create acl manager: %w", err)
 	}
@@ -226,6 +226,22 @@ func (m *Manager) DisableRouting() error {
 	return nil
 }
 
+// AddDNATRule adds a DNAT rule
+func (m *Manager) AddDNATRule(rule firewall.ForwardRule) (firewall.Rule, error) {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	return m.router.AddDNATRule(rule)
+}
+
+// DeleteDNATRule deletes a DNAT rule
+func (m *Manager) DeleteDNATRule(rule firewall.Rule) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	return m.router.DeleteDNATRule(rule)
+}
+
 func getConntrackEstablished() []string {
 	return []string{"-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"}
 }

client/firewall/iptables/router_linux.go

@@ -16,6 +16,7 @@ import (
 	nberrors "github.com/netbirdio/netbird/client/errors"
 	firewall "github.com/netbirdio/netbird/client/firewall/manager"
 	"github.com/netbirdio/netbird/client/internal/acl/id"
+	"github.com/netbirdio/netbird/client/internal/routemanager/ipfwdstate"
 	"github.com/netbirdio/netbird/client/internal/routemanager/refcounter"
 	"github.com/netbirdio/netbird/client/internal/statemanager"
 	nbnet "github.com/netbirdio/netbird/util/net"
@@ -23,22 +24,36 @@ import (
 
 // constants needed to manage and create iptable rules
 const (
-	tableFilter             = "filter"
-	tableNat                = "nat"
-	tableMangle             = "mangle"
+	tableFilter = "filter"
+	tableNat    = "nat"
+	tableMangle = "mangle"
+
 	chainPOSTROUTING        = "POSTROUTING"
 	chainPREROUTING         = "PREROUTING"
 	chainRTNAT              = "NETBIRD-RT-NAT"
-	chainRTFWD              = "NETBIRD-RT-FWD"
+	chainRTFWDIN            = "NETBIRD-RT-FWD-IN"
+	chainRTFWDOUT           = "NETBIRD-RT-FWD-OUT"
 	chainRTPRE              = "NETBIRD-RT-PRE"
+	chainRTRDR              = "NETBIRD-RT-RDR"
 	routingFinalForwardJump = "ACCEPT"
 	routingFinalNatJump     = "MASQUERADE"
 
-	jumpPre  = "jump-pre"
-	jumpNat  = "jump-nat"
-	matchSet = "--match-set"
+	jumpManglePre = "jump-mangle-pre"
+	jumpNatPre    = "jump-nat-pre"
+	jumpNatPost   = "jump-nat-post"
+	matchSet      = "--match-set"
+
+	dnatSuffix = "_dnat"
+	snatSuffix = "_snat"
+	fwdSuffix  = "_fwd"
 )
 
+type ruleInfo struct {
+	chain string
+	table string
+	rule  []string
+}
+
 type routeFilteringRuleParams struct {
 	Sources     []netip.Prefix
 	Destination netip.Prefix
@@ -62,6 +77,7 @@ type router struct {
 	legacyManagement bool
 
 	stateManager *statemanager.Manager
+	ipFwdState   *ipfwdstate.IPForwardingState
 }
 
 func newRouter(iptablesClient *iptables.IPTables, wgIface iFaceMapper) (*router, error) {
@@ -69,6 +85,7 @@ func newRouter(iptablesClient *iptables.IPTables, wgIface iFaceMapper) (*router,
 		iptablesClient: iptablesClient,
 		rules:          make(map[string][]string),
 		wgIface:        wgIface,
+		ipFwdState:     ipfwdstate.NewIPForwardingState(),
 	}
 
 	r.ipsetCounter = refcounter.New(
@@ -139,9 +156,9 @@ func (r *router) AddRouteFiltering(
 	var err error
 	if action == firewall.ActionDrop {
 		// after the established rule
-		err = r.iptablesClient.Insert(tableFilter, chainRTFWD, 2, rule...)
+		err = r.iptablesClient.Insert(tableFilter, chainRTFWDIN, 2, rule...)
 	} else {
-		err = r.iptablesClient.Append(tableFilter, chainRTFWD, rule...)
+		err = r.iptablesClient.Append(tableFilter, chainRTFWDIN, rule...)
 	}
 
 	if err != nil {
@@ -156,12 +173,12 @@ func (r *router) AddRouteFiltering(
 }
 
 func (r *router) DeleteRouteRule(rule firewall.Rule) error {
-	ruleKey := rule.GetRuleID()
+	ruleKey := rule.ID()
 
 	if rule, exists := r.rules[ruleKey]; exists {
 		setName := r.findSetNameInRule(rule)
 
-		if err := r.iptablesClient.Delete(tableFilter, chainRTFWD, rule...); err != nil {
+		if err := r.iptablesClient.Delete(tableFilter, chainRTFWDIN, rule...); err != nil {
 			return fmt.Errorf("delete route rule: %v", err)
 		}
 		delete(r.rules, ruleKey)
@@ -212,6 +229,10 @@ func (r *router) deleteIpSet(setName string) error {
 
 // AddNatRule inserts an iptables rule pair into the nat chain
 func (r *router) AddNatRule(pair firewall.RouterPair) error {
+	if err := r.ipFwdState.RequestForwarding(); err != nil {
+		return err
+	}
+
 	if r.legacyManagement {
 		log.Warnf("This peer is connected to a NetBird Management service with an older version. Allowing all traffic for %s", pair.Destination)
 		if err := r.addLegacyRouteRule(pair); err != nil {
@@ -238,6 +259,10 @@ func (r *router) AddNatRule(pair firewall.RouterPair) error {
 
 // RemoveNatRule removes an iptables rule pair from forwarding and nat chains
 func (r *router) RemoveNatRule(pair firewall.RouterPair) error {
+	if err := r.ipFwdState.ReleaseForwarding(); err != nil {
+		log.Errorf("%v", err)
+	}
+
 	if err := r.removeNatRule(pair); err != nil {
 		return fmt.Errorf("remove nat rule: %w", err)
 	}
@@ -264,7 +289,7 @@ func (r *router) addLegacyRouteRule(pair firewall.RouterPair) error {
 	}
 
 	rule := []string{"-s", pair.Source.String(), "-d", pair.Destination.String(), "-j", routingFinalForwardJump}
-	if err := r.iptablesClient.Append(tableFilter, chainRTFWD, rule...); err != nil {
+	if err := r.iptablesClient.Append(tableFilter, chainRTFWDIN, rule...); err != nil {
 		return fmt.Errorf("add legacy forwarding rule %s -> %s: %v", pair.Source, pair.Destination, err)
 	}
 
@@ -277,7 +302,7 @@ func (r *router) removeLegacyRouteRule(pair firewall.RouterPair) error {
 	ruleKey := firewall.GenKey(firewall.ForwardingFormat, pair)
 
 	if rule, exists := r.rules[ruleKey]; exists {
-		if err := r.iptablesClient.DeleteIfExists(tableFilter, chainRTFWD, rule...); err != nil {
+		if err := r.iptablesClient.DeleteIfExists(tableFilter, chainRTFWDIN, rule...); err != nil {
 			return fmt.Errorf("remove legacy forwarding rule %s -> %s: %v", pair.Source, pair.Destination, err)
 		}
 		delete(r.rules, ruleKey)
@@ -305,7 +330,7 @@ func (r *router) RemoveAllLegacyRouteRules() error {
 		if !strings.HasPrefix(k, firewall.ForwardingFormatPrefix) {
 			continue
 		}
-		if err := r.iptablesClient.DeleteIfExists(tableFilter, chainRTFWD, rule...); err != nil {
+		if err := r.iptablesClient.DeleteIfExists(tableFilter, chainRTFWDIN, rule...); err != nil {
 			merr = multierror.Append(merr, fmt.Errorf("remove legacy forwarding rule: %v", err))
 		} else {
 			delete(r.rules, k)
@@ -343,9 +368,11 @@ func (r *router) cleanUpDefaultForwardRules() error {
 		chain string
 		table string
 	}{
-		{chainRTFWD, tableFilter},
-		{chainRTNAT, tableNat},
+		{chainRTFWDIN, tableFilter},
+		{chainRTFWDOUT, tableFilter},
 		{chainRTPRE, tableMangle},
+		{chainRTNAT, tableNat},
+		{chainRTRDR, tableNat},
 	} {
 		ok, err := r.iptablesClient.ChainExists(chainInfo.table, chainInfo.chain)
 		if err != nil {
@@ -365,16 +392,22 @@ func (r *router) createContainers() error {
 		chain string
 		table string
 	}{
-		{chainRTFWD, tableFilter},
+		{chainRTFWDIN, tableFilter},
+		{chainRTFWDOUT, tableFilter},
 		{chainRTPRE, tableMangle},
 		{chainRTNAT, tableNat},
+		{chainRTRDR, tableNat},
 	} {
-		if err := r.createAndSetupChain(chainInfo.chain); err != nil {
+		if err := r.iptablesClient.NewChain(chainInfo.table, chainInfo.chain); err != nil {
 			return fmt.Errorf("create chain %s in table %s: %w", chainInfo.chain, chainInfo.table, err)
 		}
 	}
 
-	if err := r.insertEstablishedRule(chainRTFWD); err != nil {
+	if err := r.insertEstablishedRule(chainRTFWDIN); err != nil {
+		return fmt.Errorf("insert established rule: %w", err)
+	}
+
+	if err := r.insertEstablishedRule(chainRTFWDOUT); err != nil {
 		return fmt.Errorf("insert established rule: %w", err)
 	}
 
@@ -415,27 +448,6 @@ func (r *router) addPostroutingRules() error {
 	return nil
 }
 
-func (r *router) createAndSetupChain(chain string) error {
-	table := r.getTableForChain(chain)
-
-	if err := r.iptablesClient.NewChain(table, chain); err != nil {
-		return fmt.Errorf("failed creating chain %s, error: %v", chain, err)
-	}
-
-	return nil
-}
-
-func (r *router) getTableForChain(chain string) string {
-	switch chain {
-	case chainRTNAT:
-		return tableNat
-	case chainRTPRE:
-		return tableMangle
-	default:
-		return tableFilter
-	}
-}
-
 func (r *router) insertEstablishedRule(chain string) error {
 	establishedRule := getConntrackEstablished()
 
@@ -454,28 +466,43 @@ func (r *router) addJumpRules() error {
 	// Jump to NAT chain
 	natRule := []string{"-j", chainRTNAT}
 	if err := r.iptablesClient.Insert(tableNat, chainPOSTROUTING, 1, natRule...); err != nil {
-		return fmt.Errorf("add nat jump rule: %v", err)
+		return fmt.Errorf("add nat postrouting jump rule: %v", err)
 	}
-	r.rules[jumpNat] = natRule
+	r.rules[jumpNatPost] = natRule
 
-	// Jump to prerouting chain
+	// Jump to mangle prerouting chain
 	preRule := []string{"-j", chainRTPRE}
 	if err := r.iptablesClient.Insert(tableMangle, chainPREROUTING, 1, preRule...); err != nil {
-		return fmt.Errorf("add prerouting jump rule: %v", err)
+		return fmt.Errorf("add mangle prerouting jump rule: %v", err)
 	}
-	r.rules[jumpPre] = preRule
+	r.rules[jumpManglePre] = preRule
+
+	// Jump to nat prerouting chain
+	rdrRule := []string{"-j", chainRTRDR}
+	if err := r.iptablesClient.Insert(tableNat, chainPREROUTING, 1, rdrRule...); err != nil {
+		return fmt.Errorf("add nat prerouting jump rule: %v", err)
+	}
+	r.rules[jumpNatPre] = rdrRule
 
 	return nil
 }
 
 func (r *router) cleanJumpRules() error {
-	for _, ruleKey := range []string{jumpNat, jumpPre} {
+	for _, ruleKey := range []string{jumpNatPost, jumpManglePre, jumpNatPre} {
 		if rule, exists := r.rules[ruleKey]; exists {
-			table := tableNat
-			chain := chainPOSTROUTING
-			if ruleKey == jumpPre {
+			var table, chain string
+			switch ruleKey {
+			case jumpNatPost:
+				table = tableNat
+				chain = chainPOSTROUTING
+			case jumpManglePre:
 				table = tableMangle
 				chain = chainPREROUTING
+			case jumpNatPre:
+				table = tableNat
+				chain = chainPREROUTING
+			default:
+				return fmt.Errorf("unknown jump rule: %s", ruleKey)
 			}
 
 			if err := r.iptablesClient.DeleteIfExists(table, chain, rule...); err != nil {
@@ -520,6 +547,8 @@ func (r *router) addNatRule(pair firewall.RouterPair) error {
 	}
 
 	r.rules[ruleKey] = rule
+
+	r.updateState()
 	return nil
 }
 
@@ -535,6 +564,7 @@ func (r *router) removeNatRule(pair firewall.RouterPair) error {
 		log.Debugf("marking rule %s not found", ruleKey)
 	}
 
+	r.updateState()
 	return nil
 }
 
@@ -564,6 +594,137 @@ func (r *router) updateState() {
 	}
 }
 
+func (r *router) AddDNATRule(rule firewall.ForwardRule) (firewall.Rule, error) {
+	if err := r.ipFwdState.RequestForwarding(); err != nil {
+		return nil, err
+	}
+
+	ruleKey := rule.ID()
+	if _, exists := r.rules[ruleKey+dnatSuffix]; exists {
+		return rule, nil
+	}
+
+	toDestination := rule.TranslatedAddress.String()
+	switch {
+	case len(rule.TranslatedPort.Values) == 0:
+		// no translated port, use original port
+	case len(rule.TranslatedPort.Values) == 1:
+		toDestination += fmt.Sprintf(":%d", rule.TranslatedPort.Values[0])
+	case rule.TranslatedPort.IsRange && len(rule.TranslatedPort.Values) == 2:
+		// need the "/originalport" suffix to avoid dnat port randomization
+		toDestination += fmt.Sprintf(":%d-%d/%d", rule.TranslatedPort.Values[0], rule.TranslatedPort.Values[1], rule.DestinationPort.Values[0])
+	default:
+		return nil, fmt.Errorf("invalid translated port: %v", rule.TranslatedPort)
+	}
+
+	proto := strings.ToLower(string(rule.Protocol))
+
+	rules := make(map[string]ruleInfo, 3)
+
+	// DNAT rule
+	dnatRule := []string{
+		"!", "-i", r.wgIface.Name(),
+		"-p", proto,
+		"-j", "DNAT",
+		"--to-destination", toDestination,
+	}
+	dnatRule = append(dnatRule, applyPort("--dport", &rule.DestinationPort)...)
+	rules[ruleKey+dnatSuffix] = ruleInfo{
+		table: tableNat,
+		chain: chainRTRDR,
+		rule:  dnatRule,
+	}
+
+	// SNAT rule
+	snatRule := []string{
+		"-o", r.wgIface.Name(),
+		"-p", proto,
+		"-d", rule.TranslatedAddress.String(),
+		"-j", "MASQUERADE",
+	}
+	snatRule = append(snatRule, applyPort("--dport", &rule.TranslatedPort)...)
+	rules[ruleKey+snatSuffix] = ruleInfo{
+		table: tableNat,
+		chain: chainRTNAT,
+		rule:  snatRule,
+	}
+
+	// Forward filtering rule, if fwd policy is DROP
+	forwardRule := []string{
+		"-o", r.wgIface.Name(),
+		"-p", proto,
+		"-d", rule.TranslatedAddress.String(),
+		"-j", "ACCEPT",
+	}
+	forwardRule = append(forwardRule, applyPort("--dport", &rule.TranslatedPort)...)
+	rules[ruleKey+fwdSuffix] = ruleInfo{
+		table: tableFilter,
+		chain: chainRTFWDOUT,
+		rule:  forwardRule,
+	}
+
+	for key, ruleInfo := range rules {
+		if err := r.iptablesClient.Append(ruleInfo.table, ruleInfo.chain, ruleInfo.rule...); err != nil {
+			if rollbackErr := r.rollbackRules(rules); rollbackErr != nil {
+				log.Errorf("rollback failed: %v", rollbackErr)
+			}
+			return nil, fmt.Errorf("add rule %s: %w", key, err)
+		}
+		r.rules[key] = ruleInfo.rule
+	}
+
+	r.updateState()
+	return rule, nil
+}
+
+func (r *router) rollbackRules(rules map[string]ruleInfo) error {
+	var merr *multierror.Error
+	for key, ruleInfo := range rules {
+		if err := r.iptablesClient.DeleteIfExists(ruleInfo.table, ruleInfo.chain, ruleInfo.rule...); err != nil {
+			merr = multierror.Append(merr, fmt.Errorf("rollback rule %s: %w", key, err))
+			// On rollback error, add to rules map for next cleanup
+			r.rules[key] = ruleInfo.rule
+		}
+	}
+	if merr != nil {
+		r.updateState()
+	}
+	return nberrors.FormatErrorOrNil(merr)
+}
+
+func (r *router) DeleteDNATRule(rule firewall.Rule) error {
+	if err := r.ipFwdState.ReleaseForwarding(); err != nil {
+		log.Errorf("%v", err)
+	}
+
+	ruleKey := rule.ID()
+
+	var merr *multierror.Error
+	if dnatRule, exists := r.rules[ruleKey+dnatSuffix]; exists {
+		if err := r.iptablesClient.Delete(tableNat, chainRTRDR, dnatRule...); err != nil {
+			merr = multierror.Append(merr, fmt.Errorf("delete DNAT rule: %w", err))
+		}
+		delete(r.rules, ruleKey+dnatSuffix)
+	}
+
+	if snatRule, exists := r.rules[ruleKey+snatSuffix]; exists {
+		if err := r.iptablesClient.Delete(tableNat, chainRTNAT, snatRule...); err != nil {
+			merr = multierror.Append(merr, fmt.Errorf("delete SNAT rule: %w", err))
+		}
+		delete(r.rules, ruleKey+snatSuffix)
+	}
+
+	if fwdRule, exists := r.rules[ruleKey+fwdSuffix]; exists {
+		if err := r.iptablesClient.Delete(tableFilter, chainRTFWDIN, fwdRule...); err != nil {
+			merr = multierror.Append(merr, fmt.Errorf("delete forward rule: %w", err))
+		}
+		delete(r.rules, ruleKey+fwdSuffix)
+	}
+
+	r.updateState()
+	return nberrors.FormatErrorOrNil(merr)
+}
+
 func genRouteFilteringRuleSpec(params routeFilteringRuleParams) []string {
 	var rule []string
 

client/firewall/iptables/router_linux_test.go

@@ -39,12 +39,14 @@ func TestIptablesManager_RestoreOrCreateContainers(t *testing.T) {
 	}()
 
 	// Now 5 rules:
-	// 1. established rule in forward chain
-	// 2. jump rule to NAT chain
-	// 3. jump rule to PRE chain
-	// 4. static outbound masquerade rule
-	// 5. static return masquerade rule
-	require.Len(t, manager.rules, 5, "should have created rules map")
+	// 1. established rule forward in
+	// 2. estbalished rule forward out
+	// 3. jump rule to POST nat chain
+	// 4. jump rule to PRE mangle chain
+	// 5. jump rule to PRE nat chain
+	// 6. static outbound masquerade rule
+	// 7. static return masquerade rule
+	require.Len(t, manager.rules, 7, "should have created rules map")
 
 	exists, err := manager.iptablesClient.Exists(tableNat, chainPOSTROUTING, "-j", chainRTNAT)
 	require.NoError(t, err, "should be able to query the iptables %s table and %s chain", tableNat, chainPOSTROUTING)
@@ -332,14 +334,14 @@ func TestRouter_AddRouteFiltering(t *testing.T) {
 			require.NoError(t, err, "AddRouteFiltering failed")
 
 			// Check if the rule is in the internal map
-			rule, ok := r.rules[ruleKey.GetRuleID()]
+			rule, ok := r.rules[ruleKey.ID()]
 			assert.True(t, ok, "Rule not found in internal map")
 
 			// Log the internal rule
 			t.Logf("Internal rule: %v", rule)
 
 			// Check if the rule exists in iptables
-			exists, err := iptablesClient.Exists(tableFilter, chainRTFWD, rule...)
+			exists, err := iptablesClient.Exists(tableFilter, chainRTFWDIN, rule...)
 			assert.NoError(t, err, "Failed to check rule existence")
 			assert.True(t, exists, "Rule not found in iptables")
 

client/firewall/iptables/rule.go

@@ -12,6 +12,6 @@ type Rule struct {
 }
 
 // GetRuleID returns the rule id
-func (r *Rule) GetRuleID() string {
+func (r *Rule) ID() string {
 	return r.ruleID
 }