Karl Hiramoto wrote: > > Hi all, > > I have a scenario with CLIP IPoA(RFC1577) atm link over ADSL on the > WAN, 801.1q VLANs on the LAN, and NAT/MASQUERADE that does not work. > > > Network config: > Nat_host <--> router <---> server > > a ping from the Nat_host reaches the server on the WAN fine, and the > ping comes back to the router, but the ping response never reaches the > Nat_Host. Using TRACE rules it seems the ICMP ping response gets lost > inside the router. I see the same behavior with TCP and UDP. > > The problem ended up being the packet being corrupted when the vlan tag was being added and skb_cow_head() was being called. Anyone know why skb_cow_head() would corrupt the packet? Perhaps it was not allocated correctly? I'm using a big-endian ARM IXP435 board. NET_SKB_PAD change was already discussed: http://kerneltrap.org/mailarchive/linux-netdev/2009/2/7/4919204 Signed-off by: Karl Hiramoto <karl@xxxxxxxxxxxx> --- linux-2.6.28.4.a/include/linux/if_vlan.h 2009-02-06 22:47:45.000000000 +0100 +++ linux-2.6.28.4.b/include/linux/if_vlan.h 2009-02-16 13:55:35.000000000 +0100 @@ -183,9 +183,12 @@ static inline struct sk_buff *__vlan_put { struct vlan_ethhdr *veth; - if (skb_cow_head(skb, VLAN_HLEN) < 0) { - kfree_skb(skb); - return NULL; + /* If not enough headroom for vlan tag */ + if (skb_headroom(skb) < VLAN_HLEN) { + if (skb_cow_head(skb, VLAN_HLEN) < 0) { + kfree_skb(skb); + return NULL; + } } veth = (struct vlan_ethhdr *)skb_push(skb, VLAN_HLEN) --- linux-2.6.28.4.a/include/linux/skbuff.h 2009-02-06 22:47:45.000000000 +0100 +++ linux-2.6.28.4.b/include/linux/skbuff.h 2009-02-16 13:52:54.000000000 +0100 @@ -1263,7 +1263,7 @@ static inline int skb_network_offset(con * headroom, you should not reduce this. */ #ifndef NET_SKB_PAD -#define NET_SKB_PAD 16 +#define NET_SKB_PAD 32 #endif -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
