Netgraph ng_patch and ng_input: where to find packets?

Victor Gamov vit at euro-comm.net
Mon Nov 25 17:30:53 UTC 2013


Hi All

I want to get 2 or 3 copies of input packet at my system to resend it to new destinations.  So I prepare following configuration:

# ipfw add 10000 ngtee 100 udp from any to 239.0.0.19 dst-port 1234 in via vlan999

# ngctl mkpeer ipfw: hub 100 hub-in
# ngctl name ipfw:100 hub100

# ngctl mkpeer hub100: patch hub100-out1 in
# ngctl name hub100:hub100-out1 patch100
# ngctl msg patch100: setconfig '{ count=1 csum_flags=1 ops=[ { value=0xc0a8e680 offset=16 length=4 mode=1 } ] }'

Now when I connect to patch:out as 
# nghook -a patch100: out

then I see packets with new IP:

0000:  45 00 05 40 00 00 40 00 ff 11 b9 27 c0 a8 0d 12
0010:  c0 a8 e6 80 04 dc 04 dc 05 2c 00 00 47 4c ef 1a

Now I want to put this packets back into IP processing to send it to new destination 192.168.230.128 (0xc0a8e680):

# ngctl mkpeer patch100: ip_input out new100_to_dst_1

But packets not shown on outgoing interface:

# ifconfig vlan333
vlan333: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
	options=103<RXCSUM,TXCSUM,TSO4>
	ether 00:1b:21:5b:7e:e9
	inet 192.168.230.9 netmask 0xffffff00 broadcast 192.168.230.255

# arp 192.168.230.128
? (192.168.230.128) at 62:99:4c:3b:22:fc on vlan333 expires in 1190 seconds [vlan]


Can somebody explain me where I was wrong?

Thanks!

--
CU,
Victor Gamov






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