link disappears

Hello,

I'm new to networking in general and VPN in particular but need to setup infrastructure to be able to SSH easily to several people who are behind routers (NAT). After reading that WireGuard is super simple - I decided to give it try.

It indeed turned out to be simple till now. I setup a Debian virtual server with a public IP and configure it as follows:

Server:

# wg
interface: wg0
  public key: QMwhCacViCKcTrkevg5NxLnTEJDU1bTNgQp43rp7BHM=
  private key: (hidden)
  listening port: 12000

peer: hiUdjmCK+iZf8wGEB+rYxMYYBF8QoOsm3nkF3asllRY=
endpoint: 37.X.Y.Z:4488
allowed ips: 10.8.8.9/32
latest handshake: 17 minutes, 50 seconds ago
transfer: 30.94 KiB received, 22.03 KiB sent

Node behind NAT:

# wg
interface: wg0
  public key: hiUdjmCK+iZf8wGEB+rYxMYYBF8QoOsm3nkF3asllRY=
  private key: (hidden)
  listening port: 12000

peer: QMwhCacViCKcTrkevg5NxLnTEJDU1bTNgQp43rp7BHM=
endpoint: 195.A.B.C:12000
allowed ips: 10.0.0.0/8
latest handshake: 19 minutes, 11 seconds ago
transfer: 20.70 KiB received, 35.57 KiB sent persistent keepalive: every 25 seconds

Is everything OK here?... At the beginning everything worked as expected
- I could ping/SSH in both directions via the private 10.8.8.8 and 10.8.8.9 addresses. Later I put my desktop into "hibernate mode" and after turning it on again could no longer use the link...

I tried to "ip link set wg0 down" and then "... up" - handshake time gets reseted, but I do not get the link back, "ip a" shows:

6: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state UNKNOWN group default
link/none

How can I revive this link, once the wg0 interface is already configured?

(I have docker and virtualbox running on the desktop, each have its network interface... could they interfere with wg0?)

Thank you in advance!

Where is that port from?

Is everything OK here?... At the beginning everything worked as expected

I guess the NAT router in between dropped your connection by timeout. You either need to ping from behind-NAT first, to re-establish the tunnel, or if you want to do it both-ways setup portforwarding on the NAT.

Check the keepalive opions in wg, in case your NAT has only short memory.

Cheers,
Kalin.