Hi,
I'm trying to setup a NAT on my router with nftables, my LAN is wlan0
with address 192.168.20.1 and a the LAN is eth0 with address
192.168.1.7, ip forwarding is enabled:
[~]# ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:0d:b9:34:2b:e8
inet addr:192.168.1.7 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20d:b9ff:fe34:2be8/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:353 errors:0 dropped:0 overruns:0 frame:0
TX packets:305 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:39409 (38.4 KiB) TX bytes:39077 (38.1 KiB)
[~]# ifconfig wlan0
wlan0 Link encap:Ethernet HWaddr 04:f0:21:0c:a3:7d
inet addr:192.168.20.1 Bcast:192.168.20.255 Mask:255.255.255.0
inet6 addr: fe80::6f0:21ff:fe0c:a37d/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1612 Metric:1
RX packets:475 errors:0 dropped:0 overruns:0 frame:0
TX packets:232 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:48202 (47.0 KiB) TX bytes:41345 (40.3 KiB)
[~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
192.168.20.0 0.0.0.0 255.255.255.0 U 0 0 0 wlan0
[~]# cat /proc/sys/net/ipv4/ip_forward
1
I've setup nftables like this:
[~]# nft -n list table nat
table ip nat {
chain postrouting {
type nat hook postrouting priority 0;
ip saddr 192.168.20.0/24 oif eth0 snat 192.168.1.7
}
}
It correctly forwards the packet with the new address, but doesn't
send the replies back:
[~]# tcpdump -pni wlan0 icmp
IP 192.168.20.23 > 8.8.8.8: ICMP echo request, id 9107, seq 11, length 64
IP 192.168.20.23 > 8.8.8.8: ICMP echo request, id 9107, seq 12, length 64
IP 192.168.20.23 > 8.8.8.8: ICMP echo request, id 9107, seq 13, length 64
[~]# tcpdump -pni eth0 icmp
IP 192.168.1.7 > 8.8.8.8: ICMP echo request, id 9107, seq 21, length 64
IP 8.8.8.8 > 192.168.1.7: ICMP echo reply, id 9107, seq 21, length 64
IP 192.168.1.7 > 8.8.8.8: ICMP echo request, id 9107, seq 22, length 64
IP 8.8.8.8 > 192.168.1.7: ICMP echo reply, id 9107, seq 22, length 64
IP 192.168.1.7 > 8.8.8.8: ICMP echo request, id 9107, seq 23, length 64
IP 8.8.8.8 > 192.168.1.7: ICMP echo reply, id 9107, seq 23, length 64
I can't see any problem in the configuration, any hint?
Cheers,
--
Matteo Croce
OpenWrt Developer
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