Public to Public IP GRE

Question

I've managed to setup a GRE tunnel between two servers using BuyVM's very great guide (also used a guide via ServerFault) It simply works. I can ping internally

So. To get into perspective:

• A = 1.1.1.1
• B = 2.2.2.2

DDOS PROTECTED IP:

• C = 3.3.3.3

I want all traffic from A (1.1.1.1) to go to B (2.2.2.2)
Simply I want this due to DDoS protection. The latencey is 10ms between A and B so I think that's a fair trade off.

When Using buyVM's tutorial, the connection is made and both servers can ping each other in its respective IP (192.168.168.1) for A and (192.168.168.2) for B.
Now wanting to route my DDoS secured IP (3.3.3.3) to 2.2.2.2 (B)
iptables -t nat -A POSTROUTING -s 192.168.168.0/30 ! -o gre+ -j SNAT --to-source 3.3.3.3
-> Outcome of Curl

[root@DKDOS ~]# curl ipinfo.io/ip --interface 192.168.168.1 curl: (7) bind failed with errno 99: Cannot assign requested address
Could someone tell me what I am doing wrong?

Thanks

Answer 1

For each and everyone

modprobe ip_gre
modprobe ip_nat_pptp
modprobe ip_conntrack_pptp

Then per IPTables allowing the connections to happend fixed my issue. br> Thanks anyway everyone that have looked at this