NATflow

A fast forwarding stanalone kernel module with zero-patch to kernel. It could be a lite replacement of kmod-ipt-offload.

Notes

Only work for x-wrt(https://github.com/x-wrt/x-wrt)

hwnat support for mt7621/mt7622/MT7981/MT7986

hwnat with wed support for mt7622/MT7981/MT7986

port--port hwnat supported:
port-->ppe-->port
port<--ppe<--port

wifi--port hwnat supported:
wifi-->cpu-->ppe-->port
wifi<--cpu<--ppe<--port

wifi-port hwnat with wed supported:
wifi-->cpu-->ppe-->port
wifi<--ppe<--port

build

To build with path and urllogger module run:

make EXTRA_CFLAGS="-DCONFIG_NATFLOW_PATH -DCONFIG_NATFLOW_URLLOGGER"

CONFIG_HWNAT_EXTDEV_USE_VLAN_HASH option to make hwnat ext dev work via vlan hash mode, this mode would disable bridge vlan filter. this is required on MT7622 if hwnat ext dev is needed.

make EXTRA_CFLAGS="-DCONFIG_HWNAT_EXTDEV_USE_VLAN_HASH"

CONFIG_HWNAT_EXTDEV_DISABLED option to disable hwnat ext dev. if this is set, bridge vlan filter could be sure to work on MT7622.

make EXTRA_CFLAGS="-DCONFIG_HWNAT_EXTDEV_DISABLED"

Warnning

Since kernel < 4.10 cannot handle NF_STOLEN in ingress hook correctly, so kernel patch needed:

diff --git a/include/linux/netfilter_ingress.h b/include/linux/netfilter_ingress.h
index 5fcd375ef175..b407128a35c0 100644
--- a/include/linux/netfilter_ingress.h
+++ b/include/linux/netfilter_ingress.h
@@ -17,11 +17,15 @@ static inline bool nf_hook_ingress_active(const struct sk_buff *skb)
 static inline int nf_hook_ingress(struct sk_buff *skb)
 {
        struct nf_hook_state state;
+       int ret;

        nf_hook_state_init(&state, &skb->dev->nf_hooks_ingress,
                           NF_NETDEV_INGRESS, INT_MIN, NFPROTO_NETDEV,
                           skb->dev, NULL, NULL, dev_net(skb->dev), NULL);
-       return nf_hook_slow(skb, &state);
+       ret = nf_hook_slow(skb, &state);
+       if (ret == 0)
+               return -1;
+       return ret;
 }

 static inline void nf_hook_ingress_init(struct net_device *dev)
diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index f39276d1c2d7..905597547b08 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -320,6 +320,8 @@ next_hook:
                                goto next_hook;
                        kfree_skb(skb);
                }
+       } else if (verdict == NF_STOLEN) {
+               ret = 0;
        }
        rcu_read_unlock();
        return ret;

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