netfilter .. (openswan) nat problem ..

["ji'e'toh" <jietoh@o2online.de>]

i have to solv the following problem (debian 3.1, kernel 2.6.14 from kernel
org, no patches, openswan 2.x.x maybe important):

netA - gwA - gwB - netB - internet, where 

netA: 192.168.0.0/24
gwA: 192.168.0.1 + pppoe-ip-addr
gwB: 100.100.100.100 (static official ip)
netB: 100.100.100.100/32 (no real subnet)

gwA and gwB are both real gateways

tunnel works in the following way:

netA/gwA to netB/gwB and netB/gwB to netA/gwA, all I think .

now I want to forward a spezial port on gwB, perhaps 50000 to an address in
netA (192.168.0.100:50000), ok np from gwB, but ! I could not connect from
the internet over gwB to this spezial host

my nat rules, nothing else ..

iptables -t nat -A PREROUTING -j DNAT -p tcp -s 0/0 --dport 50000
--to-destination 192.168.0.100:50000 -i eth0
iptables -t nat -A POSTROUTING -j SNAT -p tcp -d 192.168.0.100 --dport 50000
--to 100.100.100.100 -o eth0

tcpdump tell me that all nat works, but no traffic on gwA interfaces
received. gwB send it, but I have a [DF] in that lines, maybe important, I
doesn't know

any suggestions? someone could help?



regards, ji