can't ping remote side IP range from WG instance

[Kalin KOZHUHAROV]

I am really not sure, but let me have a stab:

On Sun, Mar 25, 2018 at 11:19 AM, Adrián Mihálko <adriankoooo at gmail.com> wrote:
> auto wg0
> iface wg0 inet static
>   pre-up ip link add dev wg0 type wireguard
>   post-up wg setconf wg0 /etc/wireguard/wireguard.conf
>   post-up ip link set dev wg0 up
>   post-up ip route add 192.168.1.0/24 via 192.168.5.1 dev wg0
>   post-up iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
>
* I guess that should be
post-up iptables -t nat -A POSTROUTING -o wg0 -j MASQUERADE

Please try to use generic OS commands to describe the situation
whenever possible (avoiding or in addition to LEDE-specific config).
e.g.
`ip addr`
`ip route`
`wg`

* Any other iptables rules? Try disabling all FW first. (also on Ubuntu server)
* Any bridging (often the case in LEDE)?
* run tcpdump/tshark to see what is going on

> Everything is working great,
What exactly is working?

> except that on the "Pi Zero with Wireguard" I can't access/ping remote devices in the 192.168.1.0/24 range, only the remote server 192.168.1.54.
> From any other machine in the same "A side" I am able to access devices in the 192.168.1.0/24 range, just from the Pi Zero itself not.
>
So the difference here is (looking from inside Pi0), "other machine"
traverses the FORWARD chain, while "Pi Zero with Wireguard" traverses
OUTPUT (then reply via INPUT).
I guess fixing the MASQUEARADE line will do it (on both sides).

Being able to ping only the router of a remote net means that it
doesn't route the echo-request:
* due to FW policy
* due to "bad src address" (e.g. if you somehow manage to ping from
1.1.1.1 (via many tunnels) to 2.2.2.2 and 2.2.2.2 cannot directly
reach 1.1.1.1)
{I am guessing Pi0 sends ping from wg0/192.168.5.2 to Ubuntu
wg0/192.168.5.1, forwarded to 192.168.1.100, it has no route to
192.168.5.2, so sends it to 192.168.1.1 as default... asymmetric route
blocking?)

* on 192.168.1.100, run tshark to see if you even get an echo-request
packet when you try to ping it.
* What is the route to 192.168.5.2 on 192.168.1.100? (on 192.168.1.100
run `ip route get 192.168.5.2`)

And before doing any of the above, sit down and draw a map, with
colorful pens for wired and WG connections. It does help, trust me.

Kalin.