[client] Redirect dns forwarder port 5353 to new listening port 22054 (#4707)

- Port dnat changes from https://github.com/netbirdio/netbird/pull/4015 (nftables/iptables/userspace)
  - For userspace: rewrite the original port to the target port
  - Remember original destination port in conntrack
  - Rewrite the source port back to the original port for replies
- Redirect incoming port 5353 to 22054 (tcp/udp)
- Revert port changes based on the network map received from management
- Adjust tracer to show NAT stages
This commit is contained in:
Viktor Liu
2025-10-28 15:12:53 +01:00
committed by GitHub
parent 4545ab9a52
commit 404cab90ba
25 changed files with 1125 additions and 196 deletions

View File

@@ -1350,6 +1350,103 @@ func (r *router) UpdateSet(set firewall.Set, prefixes []netip.Prefix) error {
return nil
}
// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services.
func (r *router) AddInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
ruleID := fmt.Sprintf("inbound-dnat-%s-%s-%d-%d", localAddr.String(), protocol, sourcePort, targetPort)
if _, exists := r.rules[ruleID]; exists {
return nil
}
protoNum, err := protoToInt(protocol)
if err != nil {
return fmt.Errorf("convert protocol to number: %w", err)
}
exprs := []expr.Any{
&expr.Meta{Key: expr.MetaKeyIIFNAME, Register: 1},
&expr.Cmp{
Op: expr.CmpOpEq,
Register: 1,
Data: ifname(r.wgIface.Name()),
},
&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 2},
&expr.Cmp{
Op: expr.CmpOpEq,
Register: 2,
Data: []byte{protoNum},
},
&expr.Payload{
DestRegister: 3,
Base: expr.PayloadBaseTransportHeader,
Offset: 2,
Len: 2,
},
&expr.Cmp{
Op: expr.CmpOpEq,
Register: 3,
Data: binaryutil.BigEndian.PutUint16(sourcePort),
},
}
exprs = append(exprs, applyPrefix(netip.PrefixFrom(localAddr, 32), false)...)
exprs = append(exprs,
&expr.Immediate{
Register: 1,
Data: localAddr.AsSlice(),
},
&expr.Immediate{
Register: 2,
Data: binaryutil.BigEndian.PutUint16(targetPort),
},
&expr.NAT{
Type: expr.NATTypeDestNAT,
Family: uint32(nftables.TableFamilyIPv4),
RegAddrMin: 1,
RegProtoMin: 2,
RegProtoMax: 0,
},
)
dnatRule := &nftables.Rule{
Table: r.workTable,
Chain: r.chains[chainNameRoutingRdr],
Exprs: exprs,
UserData: []byte(ruleID),
}
r.conn.AddRule(dnatRule)
if err := r.conn.Flush(); err != nil {
return fmt.Errorf("add inbound DNAT rule: %w", err)
}
r.rules[ruleID] = dnatRule
return nil
}
// RemoveInboundDNAT removes an inbound DNAT rule.
func (r *router) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
if err := r.refreshRulesMap(); err != nil {
return fmt.Errorf(refreshRulesMapError, err)
}
ruleID := fmt.Sprintf("inbound-dnat-%s-%s-%d-%d", localAddr.String(), protocol, sourcePort, targetPort)
if rule, exists := r.rules[ruleID]; exists {
if err := r.conn.DelRule(rule); err != nil {
return fmt.Errorf("delete inbound DNAT rule %s: %w", ruleID, err)
}
if err := r.conn.Flush(); err != nil {
return fmt.Errorf("flush delete inbound DNAT rule: %w", err)
}
delete(r.rules, ruleID)
}
return nil
}
// applyNetwork generates nftables expressions for networks (CIDR) or sets
func (r *router) applyNetwork(
network firewall.Network,