wallet/docs/setup/wireguard.md

---
title: Wireguard
...

Setting up your own vpn using wireguard and a Debian 11 server in the cloud

This tutorial largely stolen from [Linuxbabe](https://www.linuxbabe.com/debian/wireguard-vpn-server-debian){target="_blank"}  It is slightly
more up to date than her version at the time of writing.

# WireGuard VPN

Openvpn uses ssl, (not to be confused with ssh)  Wireguard uses algorithms
and code developed by privacy advocates.  SSL has numerous well known
vulnerabilities, notably that it is subject to active attack by any group
that has a CA in its pocket.  The NSA has a passive attack, which is not
understood, but OpenSSL has an enormous  codebase, that
is impossible to audit with an architecture that seems designed for hiding
obfuscated vulnerabilities, and NSA has contributed much to its codebase
through innumerable proxies, who are evasive when I talk to them.

Wireguard uses cryptographic libraries developed by our allies, rather than our enemies.  

Wireguard is lightweight and fast, blowing OpenVPN out of the water.

Openvpn is a gigantic pile of code, a maze of strange architectural
decisions that slow things down, which vast complicated pile of
incomprehensible things seem to be to provide no useful purpose other
than places to hide backdoors in.

Wireguard is open source and and cross-platform. WireGuard can run on
Linux, BSD, macOS, Windows, Android, iOS, and OpenWRT.

User authentication is done by exchanging public keys, similar to SSH keys.

Assigns static tunnel IP addresses to VPN clients. 

Mobile devices can switch between Wi-Fi and mobile network seamlessly
without dropping any connectivity.

Supercedes OpenVPN and IPSec, which are obsolete and insecure.

# Requirements

I assume you have a host in the cloud, with world accessible network address and ports, that can access blocked websites freely outside of your country or Internet filtering system.

We are going to enable ip4 and ipv6 on our vpn.  The tutorial assumes ipv6 is working.  Check that it *is* working by pinging your server `ping -6 «server»`, then ssh in to your server and attempt to `ping -6 «something»`

It may well happen that your server is supposed to have an ipv6 address and /64 ipv6 subnet, but something is broken.


The VPN server is running Debian 11 operating system.  This tutorial is not
going to work on Debian 10 or lower.  Accessing your vpn from a windows
client, however, easy since the windows wireguard windows client is very
friendly.   Setting up wireguard on windows is easy. Setting up a wireguard
VPN server on windows is, on the other hand, very difficult.  Don't even
try.  I am unaware of anyone succeeding.

## Make sure you have control of nameservice

No end of people are strangely eager to provide free nameservice.  If it is a
free service, you are the product.  And some of them have sneaky ways to get
you use their nameservice whether you want it or not.

Nameservice reveals which websites you are visiting.  We are going to set up
our own nameserver for the vpn clients, but it will have to forward to a
bigger nameserver, thus revealing which websites the clients are visiting,
though not which client is visiting them.  Lots of people are strangely eager
to know which websites you are visiting.  If you cannot control your
nameservice, then when you set up your own nameserver, it is likely to
behave strangely.

No end of people's helpful efforts to help you automatically set up
nameservice are likely foul up your nameservice for your vpn clients.

```bash
cat /etc/resolv.conf
```

Probably at least two of them are google, which logs everything and
shares the data with the Global American Empire, and the other two are
mystery meat.  Maybe good guys provided by your good guy ISP, but I
would not bet on it.  Your ISP probably went along with his ISP, and his
ISP may be in the pocket of your enemies.

I use Yandex.com resolvers, since Russia is currently in a state of proxy
war with the Global American Empire which is heading into flat out war,
and I do not care if the Russian government knows which websites I visit,
because it is unlikely to share that data with the five eyes.

So for me

```terminal_image
cat /etc/resolv.conf
nameserver 2a02:6b8::feed:0ff
nameserver 2a02:6b8:0:1::feed:0ff
nameserver 77.88.8.8
nameserver 77.88.8.1
```

Of course your mileage may vary, depending on which enemies you are
worried about, and what the political situation is when you read this  (it
may well change radically in the near future).  Read up on the resolver's
privacy policies, but apply appropriate cynicism.  Political alignments and
vulnerability to power matter more that professed good intentions.

We are going to change this when we set up our own nameserver for the
vpn clients, but if you don't have control, things are likely to get strange. 

You cannot necessarily change your nameservers by editing
`/etc/resolv.conf`, since no end of processes are apt to rewrite that file
durig boot up.  Changing your nameservers depends on how your linux is
set up, but editing `/etc/resolv.conf` currently works on the standard
distribution.  But may well cease to work when you add more software.

If it does not work, maybe you need to subtract some software, but it is
hard to know what software.  A clean fresh install may be needed.

It all depends on which module of far too many modules gets the last
whack at `/etc/resolv.conf` on bootup.  Far too many people display a
curious and excessive interest in controlling what nameserver you are
using, and if they have their claw in your linux distribution, you are going
to have to edit the configuration files of that module.

If something is whacking your `/etc/resolv.conf`, install `openresolv`,
which will generally make sure it gets the last whack, and edit its
configuration files.  Or install a distribution where you *can* control
nameservice by editing `/etc/resolv.conf`

# Install WireGuard on Debian Client and server

```bash
apt update -qy
apt full-upgrade -qy
apt install -qy wireguard wireguard-tools linux-headers-$(uname -r)
```

## Generate Public/Private Keypairs

On the server

```bash
sudo mkdir -p /etc/wireguard
wg genkey | sudo tee /etc/wireguard/server_private.key | wg pubkey | sudo tee /etc/wireguard/server_public.key
sudo chmod 600 /etc/wireguard/ -R
```

On the client

```bash
sudo mkdir -p /etc/wireguard
wg genkey | sudo tee /etc/wireguard/private.key | wg pubkey | sudo tee /etc/wireguard/public.key
sudo chmod 600 /etc/wireguard/ -R
```
# Configure Wireguard on server

## Create WireGuard Server Configuration File

This configuration file is for two clients, one of which is a bitcoin peer for which port forwarding is provided, and to provide them a nat translated IPv4 address, and an IPv6 address on a random /112 subnet of the vpn servers /64 subnet.  Adjust to taste.  IPv6 is tricky.

Use a command-line text editor like Nano to create a WireGuard configuration file on the Debian server. `wg0` will be the network interface name.

```bash
    sudo nano /etc/wireguard/wg0.conf
```

Copy the following text and paste it to your configuration file. You need to use your own server private key and client public key.

The curly braces mean that you do not copy the text inside the curly braces, which is only there for example.  You have to substitute your own private key (since everyone now knows this private key), and your own client public key., mutas mutandis.

```default
[Interface]
# public key = CHRh92zutofXTapxNRKxYEpxzwKhp3FfwUfRYzmGHR4=
Address = 10.10.10.1/24, 2405:4200:f001:13f6:7ae3:6c54:61ab:0001/112
ListenPort = 115
PrivateKey = iOdkQoqm5oyFgnCbP5+6wMw99PxDb7pTs509BD6+AE8=

[Peer]
PublicKey = rtPdw1xDwYjJnDNM2eY2waANgBV4ejhHEwjP/BysljA=
AllowedIPs = 10.10.10.4/32,  2405:4200:f001:13f6:7ae3:6c54:61ab:0009/128

[Peer]
PublicKey = YvBwFyAeL50uvRq05Lv6MSSEFGlxx+L6VlgZoWA/Ulo=
AllowedIPs = 10.10.10.8/32,  2405:4200:f001:13f6:7ae3:6c54:61ab:0019/128

[Peer]
PublicKey = XpT68TnsSMFoZ3vy/fVvayvrQjTRQ3mrM7dmyjoWJgw=
AllowedIPs = 10.10.10.12/32,  2405:4200:f001:13f6:7ae3:6c54:61ab:0029/128

[Peer]
PublicKey =  f2m6KRH+GWAcCuPk/TChzD01fAr9fHFpOMbAcyo3t2U=
AllowedIPs = 10.10.10.16/32,  2405:4200:f001:13f6:7ae3:6c54:61ab:0039/128
```

```default
[Interface]
Address = 10.10.10.1/24
ListenPort = «51820»
PrivateKey = «cD+ZjXiVIX+0iSX1PNijl4a+88lCbDgw7kO78oXXLEc=»

[Peer]
PublicKey = «AYQJf6HbkQ0X0Xyt+cTMTuJe3RFwbuCMF46LKgTwzz4=»
AllowedIPs = 10.10.10.2/32
```

As always «...» means that this is an example value, and you need to
substitute your own actual value.   "_Mutas mutandis_" means "changing that
which ought to be changed".  In other words, watch out for those   «...» .

Or, as those that want to baffle you would say, metasyntactic variables are enclosed in «...» .


Where:

- **Address**: Specify the private IP address of the VPN server. Here I’m using the 10.10.10.0/24 network range, so it won’t conflict with your home network range. (Most home routers use 192.168.0.0/24 or 192.168.1.0/24). 10.10.10.1 is the private IP address for the VPN server.
- **PrivateKey**: The private key of VPN server, which can be found in the `/etc/wireguard/server_private.key` file on the server.
- **ListenPort**: WireGuard VPN server will be listening on UDP port 51820, which is the default.
- **PublicKey**: The public key of VPN client, which can be found in the `/etc/wireguard/public.key` file on the client computer.
- **AllowedIPs**: IP addresses the VPN client is allowed to use. In this example, the client can only use the 10.10.10.2 IP address inside the VPN tunnel.

Change the file permission mode so that only root user can read the files.  Private keys are supposed to be _private_,

```bash
sudo chmod 600 /etc/wireguard/ -R
```

## Configure IP Masquerading on the Server

We need to set up IP masquerading in the server firewall, so that the server becomes a virtual router for VPN clients. I will use UFW, which is a front end to the iptables firewall. Install UFW on Debian with:

``` bash
apt -qy install ufw
```

If ufw is already installed and running

``` bash
ufw disable
```

First, you need to allow SSH traffic.

```bash
ufw allow 22/tcp
```

Next, find the name of your server’s main network interface.

```bash
ip addr | grep BROADCAST
server_network_interface=$(ip addr | grep BROADCAST |sed -r "s/.*:[[:space:]]*([[:alnum:]]+)[[:space:]]*:.*/\1/")
echo $server_network_interface
```

As you can see, it’s named `eth0` on my Debian server.

```terminal_image
:~# ip addr | grep BROADCAST
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq state UP group default qlen 1000
:~# server_network_interface=$(ip addr | grep BROADCAST |sed -r "s/([[:alnum:]]+):[[:space:]]*(.*)[[:space:]]*:(.*)/\2/")
:~# echo $server_network_interface
eth0
```

To configure IP masquerading, we have to add iptables command in a UFW configuration file.

```bash
 nano /etc/ufw/before.rules
```

By default, there are some rules for the `filter` table. Add the following
lines at the end of these default rules. Replace `eth0` with your own
network interface name.

    # NAT table rules
    *nat
    :POSTROUTING ACCEPT [0:0]
    -F
    -A POSTROUTING -o «eth0» -j MASQUERADE

    # End each table with the 'COMMIT' line or these rules
    # won't be processed
    COMMIT

"MASQUERADE" is NAT packet translation.  This puts your IP4
forwarded network addresses behind a NAT firewall, so that they appear
on the internet with network address of the server.

If you want to NAT translate your IPv6 addresses, will have to do
something similar in `/etc/ufw/before6.rules`.  But you usually have lots
of IPv6 addresses, so you seldom want to nat translate IPv6

In Nano text editor, you can go to the end of the file by pressing `Ctrl+W`, then pressing `Ctrl+V`.

```terminal_image
-A ufw-before-input -p udp -d 239.255.255.250 --dport 1900 -j ACCEPT

# don't delete the 'COMMIT' line or these rules won't be processed
COMMIT

# NAT table rules
*nat
:POSTROUTING ACCEPT [0:0]
-F
-A POSTROUTING -o eth0 -j MASQUERADE
COMMIT
```

The above lines will append `-A` a rule to the end of the`POSTROUTING` chain of  the `nat` table. It will link your virtual private network with the Internet. And also hide your network from the outside world. So the Internet can only see your VPN server’s IP, but can’t see your VPN client’s IP, just like your home router hides your private home network.

Like your home router, it means your client system behind the nat has no open ports.

If you want to open some ports, for example the bitcoin port 8333 so that you can run bitcoin core and the monaro ports.

```terminal_image
NAT table rules
*nat
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A POSTROUTING -o eth0 -j MASQUERADE
-A PREROUTING -d «123.45.67.89»/32 -i eth0 -p tcp --dport 8333 -j DNAT --to-destination 10.10.10.«5»:8333
-A PREROUTING -d «123.45.67.89»/32 -i eth0 -p udp --dport 8333 -j DNAT --to-destination 10.10.10.«5»:8333
-A PREROUTING -d «123.45.67.89»/32 -i eth0 -p tcp --dport 18080 -j DNAT --to-destination 10.10.10.«5»:18080
-A PREROUTING -d «123.45.67.89»/32 -i eth0 -p tcp --dport 18089 -j DNAT --to-destination 10.10.10.«5»:18089

COMMIT
```

Then open the corresponding ports in ufw

```bash
ufw allow in  8333
ufw enable
ufw status verbose
```

If you have made an error in `/etc/ufw/before6.rules` enable will fail.

If you have enabled UFW before, then you can use systemctl to restart UFW.

## Configure forwarding on the Server

### Allow routing

By default, UFW forbids packet forwarding. We can allow forwarding for our private network,  mutas mutandis.

```bash
ufw route allow in on wg0
ufw route allow out on wg0
ufw allow in on wg0
ufw allow in from 10.10.10.0/24
ufw allow in from 2405:4200:f001:13f6:7ae3:6c54:61ab:0001/112
ufw allow «51820»/udp
ufw allow to 10.10.10.1/24
ufw allow to 2405:4200:f001:13f6:7ae3:6c54:61ab:0001/112
```

As always «...» means that this is an example value, and you need to substitute your actual value.   "_Mutas mutandis_" means "changing that which should be changed", in other words, watch out for those   «...» .

Note that the last line is intended to leave your clients naked on the IPv6
global internet with their own IPv6 addresses, as if they were in the cloud
with no firewall.  This is often desirable for linux systems, but dangerous
for windows, android, and mac systems which always have loads of
undocumented closed source mystery meat processes running that do who
knows what.

You could open only part of the IPv6 subnet to incoming, and put
windows, mac, and android clients in the part that is not open.

`wg0` is the virtual network card that `wg0.conf` specifies.  If you called it `«your name».conf` then mutatis mutandis.

### Enable routing

You just told ufw to allow your vpn clients to see each other on the internet, but allowing routing does not in itself result in any routing.

To actually enable routing, edit the system kernel configuration file, and uncomment the following lines. `nano  /etc/sysctl.conf`

```terminal_image
# Uncomment the next line to enable packet forwarding for IPv4
net.ipv4.ip_forward=1

# Uncomment the next line to enable packet forwarding for IPv6
#  Enabling this option disables Stateless Address Autoconfiguration
#  based on Router Advertisements for this host
net.ipv6.conf.all.forwarding=1
```

For these changes to take effect:

```bash
sysctl -p
```

Now if you list the rules in the POSTROUTING chain of the NAT table by using the following command:

```bash
iptables -t nat -L POSTROUTING
```

You can see the Masquerade rule.

```terminal_image
:~# iptables -t nat -L POSTROUTING
Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
MASQUERADE  all  --  anywhere             anywhere
```
## Install a DNS Resolver on the Server

Since we will specify the VPN server as the DNS server for client, we need to run a DNS resolver on the VPN server. We can install the bind9 DNS server.

```bash
apt install bind9
```

Once it’s installed, BIND will automatically start. You can check its status with:

```bash
systemctl status bind9
```

Sample output:

```terminal_image
:~$ systemctl status bind9
● named.service - BIND Domain Name Server
     Loaded: loaded (/lib/systemd/system/named.service; enabled; vendor preset: enabled)
     Active: active (running) since Wed 2022-09-21 20:14:33 EDT; 6min ago
       Docs: man:named(8)
   Main PID: 1079 (named)
      Tasks: 5 (limit: 1132)
     Memory: 16.7M
        CPU: 86ms
     CGroup: /system.slice/named.service
             └─1079 /usr/sbin/named -f -u bind

Sep 21 20:14:33 rho.la named[1079]: command channel listening on ::1#953
Sep 21 20:14:33 rho.la named[1079]: managed-keys-zone: loaded serial 0
Sep 21 20:14:33 rho.la named[1079]: zone 0.in-addr.arpa/IN: loaded serial 1
Sep 21 20:14:33 rho.la named[1079]: zone 127.in-addr.arpa/IN: loaded serial 1
Sep 21 20:14:33 rho.la named[1079]: zone 255.in-addr.arpa/IN: loaded serial 1
Sep 21 20:14:33 rho.la named[1079]: zone localhost/IN: loaded serial 2
Sep 21 20:14:33 rho.la named[1079]: all zones loaded
Sep 21 20:14:33 rho.la named[1079]: running
Sep 21 20:14:33 rho.la named[1079]: managed-keys-zone: Initializing automatic trust anchor management for zone '.'; >
Sep 21 20:14:33 rho.la named[1079]: resolver priming query complete
```

If it’s not running, start it with:

```bash
systemctl start bind9
```

Check that lookups still work:

```bash
curl -6 icanhazip.com
curl -4 icanhazip.com
```

See what dns server you are in fact using

```bash
dig icanhazip.com
```

You will notice you are not using your own bind9

Edit the BIND DNS server’s configuration file.

```bash
nano /etc/bind/named.conf.options
```

Add some acls above the options block, one for your networks, and one for potential attackers.

Add some real forwarders

And add allow recursion for your subnets.

After which it should look something like this:


```terminal_image
:~# cat /etc/bind/named.conf.options | tail -n 9
acl bogusnets {
    0.0.0.0/8;  192.0.2.0/24; 224.0.0.0/3;
    10.0.0.0/8; 172.16.0.0/12; 192.168.0.0/16;
};

acl my_net {
        127.0.0.1;
        ::1;
        116.251.216.176;
        10.10.10.0/24;
        2405:4200:f001:13f6::/64;
};

options {
   directory "/var/cache/bind";
    forwarders {
        2a02:6b8::feed:0ff;
        2a02:6b8:0:1::feed:0ff;
        77.88.8.8;
        77.88.8.1;
    };

    //==========================
    // If BIND logs error messages about the
    // root key being expired,
    // you will need to update your keys. 
    // See https://www.isc.org/bind-keys
    //==========================
    
    dnssec-validation auto;

    listen-on-v6 { any; };

    allow-recursion { my_net; };
    blackhole { bogusnets; };
    };
```

Then edit the `/etc/default/named` files.

```bash
nano /etc/default/named
```

If on an IPv4 network, add `-4` to the `OPTIONS` to ensure BIND can query root DNS servers.

    OPTIONS="-u bind -4"

If on the other hand, you are on a network that supports both IPv6 and
IPv4, this will cause unending havoc and chaos, as bind9's behavior
comes as a surprise to other components of the network, and bind9 crashes
on IPv6 information in its config files.

Save and close the file.

Restart `bind9` for the changes to take effect.

```bash
systemctl restart bind9
systemctl status bind9
dig -t txt -c chaos VERSION.BIND @127.0.0.1
```

Your ufw firewall will allow vpn clients to access `bind9` because you earlier allowed everything from `wg0` in.


## Start WireGuard on the server

Run the following command on the server to start WireGuard.

```bash
wg-quick up /etc/wireguard/wg0.conf
```

To stop it, run

```bash
wg-quick down /etc/wireguard/wg0.conf
```

You can also use systemd service to start WireGuard.

```bash
systemctl start wg-quick@wg0.service
```

Enable auto-start at system boot time.

```bash
systemctl enable wg-quick@wg0.service
```

Check its status with the following command. Its status should be `active (exited)`.

```bash
systemctl status wg-quick@wg0.service
```

Now WireGuard server is ready to accept client connections.

# Configure Wireguard on Debian 11 client.

```bash
apt -qy install openresolv
nano /etc/wireguard/wg-client0.conf
```

You will edit the wireguard client config file so that the client will use
`openresolv` to use your server's resolver to find the network addresses of
domain names instead of leaking your activities all over the internet.

Copy the following text and paste it to your configuration file. You need to
use your own client private key and server public key, _and your own endpoint and port_.
Remember, curly braces mean that the material is only
for example, and has to be customized.  Mutas mutandis.  Metasyntactic variables.

```default
[Interface]
Address = 10.10.10.2/24
DNS = 10.10.10.1
PrivateKey = «cOFA+x5UvHF+a3xJ6enLatG+DoE3I5PhMgKrMKkUyXI=»

[Peer]
PublicKey = «kQvxOJI5Km4S1c7WXu2UZFpB8mHGuf3Gz8mmgTIF2U0=»
AllowedIPs = 0.0.0.0/0
Endpoint = «123.45.67.89:51820»
PersistentKeepalive = 25
```

Where:

- `Address`: Specify the private IP address of the VPN client.
- `DNS`: specify 10.10.10.1 (the VPN server) as the DNS server. It will be configured via the `resolvconf` command. You can also specify multiple DNS servers for redundancy like this: `DNS = 10.10.10.1 8.8.8.8`
- `PrivateKey`: The client’s private key, which can be found in the `/etc/wireguard/private.key` file on the client computer.
- `PublicKey`: The server’s public key, which can be found in the `/etc/wireguard/server_public.key` file on the server.
- `AllowedIPs`: 0.0.0.0/0 represents the whole Internet, which means all traffic to the Internet should be routed via the VPN.
- `Endpoint`: The public IP address and port number of VPN server. Replace 123.45.67.89 with your server’s real public IP address and the port number with your server’s real port number.
- `PersistentKeepalive`: Send an authenticated empty packet to the peer every 25 seconds to keep the connection alive. If PersistentKeepalive isn’t enabled, the VPN server might not be able to ping the VPN client.

Save and close the file.

Change the file mode so that only root user can read the files.

```bash
chmod 600 /etc/wireguard/ -R
```

Start WireGuard.

```bash
systemctl start wg-quick@wg-client0.service
```

Enable auto-start at system boot time.

```bash
systemctl enable wg-quick@wg-client0.service
```

Check its status:

```bash
systemctl status wg-quick@wg-client0.service
```

Now go to this website: `http://icanhazip.com/` to check your public IP address. If everything went well, it should display your VPN server’s public IP address instead of your client computer’s public IP address.

You can also run the following command to get the current public IP address.

```bash
curl https://icanhazip.com
```

To get the geographic location
```bash
curl https://www.dnsleaktest.com |grep from
```

# Troubleshooting

## Check if UDP port «51820» is open

Install the `tshark` network traffic analyzer on the server. Tshark is the command-line version of Wireshark.

```bash
apt install -qy tshark
adduser «your-username» wireshark
su -l «your-username»
tshark -i «eth0» "udp port «51820»"
```

If you are asked “_Should non-superusers be able to capture packets?_”,
answer _Yes_. Once it’s installed, run the following command to add your
user account to the `wireshark` group so that you can capture packets.

If the WireGuard client is able to connect to UDP port «51820» of the server, then you will see packets being captured by tshark like below. As you can see, the client started the handshake initiation, and the server sent back a handshake response. Once the connection is established, the client sends keepalive packets.

```terminal_image
Capturing on 'eth0'
  1 105.092578905 11.22.33.44 → 12.34.56.78 WireGuard 190 Handshake Initiation, sender=0x3F1A04AB
  2 110.464628716 12.34.56.78 → 11.22.33.44 WireGuard 134 Handshake Response, sender=0x34ED7471, receiver=0xD4B23800
  3 110.509517074 11.22.33.44 → 12.34.56.78 WireGuard 74 Keepalive, receiver=0x34ED7471, counter=0
```

If the WireGuard client can not connect to UDP port 51820 of the server, then you will only see handshake initiation packets. There’s no handshake respsonse.

```terminal_image
Capturing on 'eth0' 
   1 105.092578905 11.22.33.44 → 12.34.56.78 WireGuard 190 Handshake Initiation, sender=0x3F1A04AB
    2 149.670118573 11.22.33.44 → 12.34.56.78 WireGuard 190 Handshake Initiation, sender=0x7D584974
        3 152.575188680 11.22.33.44 → 12.34.56.78 WireGuard 190 Handshake Initiation, sender=0x8D2407B9
        4 153.706876729 12.34.56.78 → 11.22.33.44 WireGuard 190 Handshake Initiation, sender=0x47690027
        5 154.789959772 11.22.33.44 → 12.34.56.78 WireGuard 190 Handshake Initiation, sender=0x993232FC
        6 157.956576772 11.22.33.44 → 12.34.56.78 WireGuard 190 Handshake Initiation, sender=0x06AD433B
        7 159.082825929 12.34.56.78 → 11.22.33.44 WireGuard 190 Handshake Initiation, sender=0x8C089E1
```

## Ping test

You can ping from the VPN server to VPN client (`ping 10.10.10.2`) to see if the tunnel works. If you see the following error message in the ping,

```terminal_image
ping: sendmsg: Required key not available
```

it might be that the `AllowedIPs`  parameter is wrong, like a typo.

If the ping error message is

```terminal_image
ping: sendmsg: Destination address required
```

it could be that the private/public key is wrong in your config files.

## Not able to browse the Internet

If the VPN tunnel is successfully established, but the client public IP
address doesn’t change, that’s because the masquerading or forwarding
rule in your UFW config file is not working, typically typo in the
`/etc/ufw/before.rules` file

## Enable Debug logging in Linux Kernel

If you use Linux kernel 5.6+, you can, as root, enable debug logging for
WireGuard with the following command.  As a non root wireguard user,
cannot log kernel.

    sudo su -
    echo module wireguard +p > /sys/kernel/debug/dynamic_debug/control

Then you can view the debug logs with

    sudo dmesg -wH

or

    sudo journalctl -kf

## Restart

If your VPN still doesn’t work, try restarting the VPN server and client.

# Adding Additional VPN Clients

WireGuard is designed to associate one IP address with one VPN client. To add more VPN clients, you need to create a unique private/public key pair for each client, then add each VPN client’s public key in the server’s config file (`/etc/wireguard/wg0.conf`) like this:

```default
[Interface]
Address = 10.10.10.1/24
PrivateKey = «UIFH+XXjJ0g0uAZJ6vPqsbb/o68SYVQdmYJpy/FlGFA=»
ListenPort = «51820»

[Peer]
PublicKey = «75VNV7HqFh+3QIT5OHZkcjWfbjx8tc6Ck62gZJT/KRA=»
AllowedIPs = 10.10.10.2/32

[Peer]
PublicKey = «YYh4/1Z/3rtl0i7cJorcinB7T4UOIzScifPNEIESFD8=»
AllowedIPs = 10.10.10.3/32

[Peer]
PublicKey = «EVstHZc6QamzPgefDGPLFEjGyedJk6SZbCJttpzcvC8=»
AllowedIPs = 10.10.10.4/32
```

Each VPN client will have a static private IP address (10.10.10.2,
10.10.10.3, 10.10.10.4, etc). Restart the WireGuard server for the changes
to take effect.

Then add WireGuard configuration on each VPN client as usual.

## Configure VPN Client on iOS/Andorid

Install the `WireGuard` app from the App store. Then open this app and click the `Add a tunnel` button.

You have 3 methods to create a new WireGuard tunnel.

- create from file or archive
- create from QR code
- Create from scratch

"Create from scratch" means that the Wireguard app gives you a private and public key pair, and an empty wg-client.conf file that you populate in
the wireguard app ui.  This is likely to result in a lot of typing where you
are bound to do a typo, even though the correct and working information
is already on your debian server and client and you would like to just copy
and paste it.

Create from QR code means that you create `ios.conf` in your client, as before for debian, add the public key to your server `wg0.conf` as before for debian, restart the server as before, and then generate the QR code with

```bash
apt install -qy qrencode
cat /etc/wireguard/ios.conf | qrencode -t ansiutf8
```
This is apt to be easier, because it is likely to be hard to transfer information between android systems.

Grencode is very useful for transferring data to android systems, which tend to be locked down against ordinary users transferring computer data.

## Configure  VPN Client on Windows 

Download the [WireGuard installer for Windows](https://www.wireguard.com/install/).

Once it’s installed, start the WireGuard program. You need to right-click
on the left sidebar to _create a new empty tunnel_. It will automatically
create a public/private key for the Windows client.

And from there on, same as with the android client.

On Windows, you can [use the PowerShell program to SSH into your
Linux server](https://www.linuxbabe.com/linux-server/ssh-windows), so you do not have the problem you had with android.


# Policy Routing, Split Tunneling & VPN Kill Switch

It’s not recommended to use _policy routing_, _split tunneling_, or _VPN kill switch_ in conjunction with each other. If you use policy routing, then you should not enable split tunneling or VPN kill switch, and vice versa.

## Policy Routing

By default, all traffic on the VPN client will be routed through the VPN
server. Sometimes you may want to route only a specific type of traffic,
based on the transport layer protocol and the destination port. This is
known as policy routing.

Policy routing is configured on the client computer, and we need to stop
the WireGuard client process and edit the client configuration file.

```bash
systemctl stop wg-quick@wg0.service
nano /etc/wireguard/wg-client0.conf
```

For example, if you add the following 3 lines in the `[interface]` section,
then WireGuard will create a routing table named “1234” and add the ip rule
into the routing table. In this example, traffic will be routed through VPN
server only when TCP is used as the transport layer protocol and the
destination port is 25, i.e, when the client computer sends emails.

```default
Table = 1234
PostUp = ip rule add ipproto tcp dport 25 table 1234
PreDown = ip rule delete ipproto tcp dport 25 table 1234
```

```terminal_image
[Interface]
Address = 10.10.10.2/24
DNS = 10.10.10.1
PrivateKey = «cOFA+x5UvHF+a3xJ6enLatG+DoE3I5PhMgKrMKkUyXI=»
Table = 1234
PostUp = ip rule add ipproto tcp dport 25 table 1234
PreDown = ip rule delete ipproto tcp dport 25 table 1234

[Peer]
PublicKey = «kQvxOJI5Km4S1c7WXu2UZFpB8mHGuf3Gz8mmgTIF2U0=»
AllowedIPs = 0.0.0.0/0
Endpoint = «123.45.67.89:51820»
PersistentKeepalive = 25
```

Save and close the file. Then start WireGuard client again.

## Split Tunneling

By default, all traffic on the VPN client will be routed through the VPN
server. Here’s how to enable split tunneling, so only traffic to the
`10.10.10.0/24` IP range will be tunneled through WireGuard VPN. This is useful when you want to build a private network for several cloud servers, because VPN clients will run on cloud servers and if you use a full VPN tunnel, then you will probably lose connection to the cloud servers.

Edit the client configuration file.

```default
nano /etc/wireguard/wg-client0.conf
```

Change

```default
AllowedIPs = 0.0.0.0/0
```

To

```default
AllowedIPs = 10.10.10.0/24
```

So traffic will be routed through VPN only when the destination address is
in the 10.10.10.0/24 IP range. Save and close the file. Then restart WireGuard client.

    sudo systemctl restart wg-quick@wg0.service

## VPN Kill Switch

By default, your computer can access the Internet via the normal gateway
when the VPN connection is disrupted. You may want to enable the kill switch
feature, which prevents the flow of unencrypted packets through
non-WireGuard interfaces.

Stop the WireGuard client process and the client configuration file.

```default
systemctl stop wg-quick@wg0.service
nano /etc/wireguard/wg-client0.conf
````

Add the following two lines in the `[interface]` section.

```default
PostUp = iptables -I OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT
PreDown = iptables -D OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT
```

Like this:
```terminal_image
[Interface]
Address = 10.10.10.2/24
DNS = 10.10.10.1
PrivateKey = cOFA+x5UvHF+a3xJ6enLatG+DoE3I5PhMgKrMKkUyXI=
PostUp = iptables -I OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT
PreDown = iptables -D OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT

[Peer]
PublicKey = kQvxOJI5Km4S1c7WXu2UZFpB8mHGuf3Gz8mmgTIF2U0=
AllowedIPs = 0.0.0.0/0
Endpoint = 12.34.56.78:51820
PersistentKeepalive = 25
```

Save and close the file. Then start the WireGuard client.