1y ago

Weird Wireguard issues I could use some help with.

I've hit a wall with a weird Wireguard issue. I'm trying to connect my phone (over cell) to my home router using wireguard and it will not connect.

The keys are all correct.
The IPs are all correct.
The ports are open on the firewall.
My router has a public IP, no CGNAT.

The router is opnsense, I have a tcpdump session going and when I attempt a connection from the phone I see 0 packets on that port. I am able to ping the router and reach the web server sitting behind it from the phone.

I have a VPS that I configured WG on and the phone connects fine to that. I also tested configuring the VPS to connect to my home router and that also works fine.

I'm really at a loss as to where to go next.

Edit 2: I completely blew out the config on both sides and rebuilt it from scratch, using a different UDP port, and it all appears to be working now. Thanks for everyone's help in tracking this down.

Edit: It was requested I provide my configs.

opnsense:

 undefined

    
####################################################
# Interface settings, not used by `wg`             #
# Only used for reference and detection of changes #
# in the configuration                             #
####################################################
# Address =  172.31.254.1/24
# DNS =
# MTU =
# disableroutes = 0
# gateway =

[Interface]
PrivateKey = 
ListenPort = 51821

[Peer]
# friendly_name = note20
PublicKey = 
AllowedIPs = 172.31.254.100/32

Android:

 undefined

    
[Interface]
Address = 172.31.254.100/32
PrivateKey = 

[Peer]
AllowedIPs = 0.0.0.0/32
Endpoint = :51821
PublicKey =

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29 comments

Did you setup a NAT on the firewall? You have to setup a static NAT on the interface that your Public IP sits on and to the private IP address of your VPS (you are using a private network space from one of the other interfaces on your FW right?).
Make sure that the policy that you create with the NAT includes UDP 51820 (unless you changed the default port) People often mistake using TCP which is a different protocol. If that doesn’t work, then look at the traffic on your FW
- Meant to say if you still get stuck, run Wireshark on your FW and your VPS and run a tcp dump and filter the traffic to see where the data stops.
  You can also use traceroute to your public IP on the port 51820 and check your connectivity or even curl: -v http:////publicip:51820
  
  Yeah I would probably try if the phone can actually access anything on that port.
  On router: netcat -vvvl 0.0.0.0 51820
  On phone: http://router_ip:51820
  The browser will fail opening it but on router you should see the first incoming HTTP GET packet.
  Or one could run a local shell on the phone (assuming android) and try netcat too.
  (or this http server one liner python3 -m http.server can be used instead of netcat)
  
  I have an network tools app that lets me test arbitrary ports and I do see those packets on a tcpdump, but this app (and you're suggestions above) are all TCP while Wireguard listens on UDP. I haven't come up with a way to test UDP from the phone yet.
  
  Netcat can do UDP with -u flag, to get netcat on the phone (android) you could try local shell (Connect Bot app can do it) and try calling the local netcat (nc, though it's a simple busybox implementation so it might not have all the features). Not sure if it would let you send udp just like that.
  
  They call it a tcpdump but Wireshark analyzes all network traffic. You can use the udp.port == 51820
  Do you have a laptop? Probably more tools and easier to test from there.
- There's some confusion here. I'm running wireguard on my opnsense router and I'm trying to connect my Android phone to it.
  I just used the VPS to help troubleshoot to show other clients can connect to opnsense AND the phone can connect to other servers but the phone and opn won't talk.
  I know this screams config issue. I've gone over it and rebuilt it multiple times. I can't find anything wrong. Someone else asked to see configs so I'll post those tomorrow.
  
  It is a config issue. Allowed IPs for your client should be 0.0.0.0/0 not 0.0.0.0/32

29 comments