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Krzysztof Błażewicz avatar Server

EC2 instance running Ubuntu as a router to Wireguard network

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Krzysztof Błażewicz

I have one machine in AWS EC2 running Ubuntu 16.04 (B) with Wireguard running as a VPN server for some Road Warrior devices (C).

I'll try to sketch it below:

+-----+                              +-----+                            +-----+
|     | ---------------------------> |     | -------------------------> |     |
|  A  | 172.30.0.5/16  172.30.0.6/16 |  B  | 10.70.0.1/24  10.70.0.2/32 |  C  |
|     | ens5                    eth0 |     | wg0                    wg0 |     |
+-----+                              +-----+                            +-----+

I want to route traffic addressed to 10.70.0.0/24 from (A) to (C) via (B).

I tried following config:

On host (A):

ip route add 10.70.0.0/24 via 172.30.0.6

EC2 security group allows all trafic to and from 172.16.0.0/12.

On host (B):

sysctl -w net.ipv4.ip_forward 1
ufw allow from 172.16.0.0/12
ufw route allow out on wg0
iptables -t nat -A POSTROUTING -s 172.16.0.0/12 -o wg0 -j MASQUERADE

I've verified forwarding is enabled for all interfaces as descibed here: https://askubuntu.com/a/923292

net.ipv4.conf.eth0.forwarding = 1
net.ipv4.conf.wg0.forwarding = 1

EC2 security group allows all trafic to and from 172.16.0.0/12.

I even tried setting DEFAULT_FORWARD_POLICY="ACCEPT" in /etc/default/ufw.

I'm out of ideas what else is missing here, I can't get any packets to pass through. On host (B) iptables doesn't see any packets going through its FORWARD chain:

iptables -nv -L FORWARD
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
    0     0 ufw-before-logging-forward  all  --  *      *       0.0.0.0/0            0.0.0.0/0
    0     0 ufw-before-forward  all  --  *      *       0.0.0.0/0            0.0.0.0/0
    0     0 ufw-after-forward  all  --  *      *       0.0.0.0/0            0.0.0.0/0
    0     0 ufw-after-logging-forward  all  --  *      *       0.0.0.0/0            0.0.0.0/0
    0     0 ufw-reject-forward  all  --  *      *       0.0.0.0/0            0.0.0.0/0
    0     0 ufw-track-forward  all  --  *      *       0.0.0.0/0            0.0.0.0/0
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Justin Ludwig
Make sure you disable AWS's packet [source/destination check](https://docs.aws.amazon.com/vpc/latest/userguide/VPC_NAT_Instance.html#EIP_Disable_SrcDestCheck) for host B.
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