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vpn/IMPLEMENTATION.md
mguschin b117efc604 Init
2026-02-02 20:11:05 +03:00

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Implementation Plan

Prerequisites

  • SSH access to both VDS servers (RU: 176.124.216.197, DE: 194.31.173.178)
  • Root or sudo privileges on both servers
  • Basic firewall rules allowing SSH access

Phase 1: DE VDS Setup (Exit Node)

The simpler node - just accepts traffic from RU VDS and NATs it to the internet.

Step 1.1: Install packages

apt update && apt install -y wireguard nftables

Step 1.2: Enable IP forwarding

echo 'net.ipv4.ip_forward = 1' >> /etc/sysctl.d/99-vpn.conf
sysctl -p /etc/sysctl.d/99-vpn.conf

Step 1.3: Generate WireGuard keys

mkdir -p /etc/wireguard/keys
chmod 700 /etc/wireguard/keys
wg genkey | tee /etc/wireguard/keys/server.key | wg pubkey > /etc/wireguard/keys/server.pub
chmod 600 /etc/wireguard/keys/*

Step 1.4: Create WireGuard config

Create /etc/wireguard/wg0.conf:

[Interface]
Address = 10.20.0.2/30
ListenPort = 51821
PrivateKey = <DE_SERVER_PRIVATE_KEY>
PostUp = nft -f /etc/nftables.conf
PostDown = nft flush ruleset

[Peer]
# RU VDS
PublicKey = <RU_SERVER_PUBLIC_KEY>
AllowedIPs = 10.20.0.1/32, 10.10.0.0/24

Step 1.5: Configure nftables

Create /etc/nftables.conf:

#!/usr/sbin/nft -f

flush ruleset

table inet filter {
    chain input {
        type filter hook input priority 0; policy drop;

        # Allow established connections
        ct state established,related accept

        # Allow loopback
        iif lo accept

        # Allow SSH (adjust port if needed)
        tcp dport 22 accept

        # Allow WireGuard from RU VDS only
        ip saddr 176.124.216.197 udp dport 51821 accept

        # Allow ICMP
        icmp type echo-request accept
    }

    chain forward {
        type filter hook forward priority 0; policy drop;

        # Allow forwarding from VPN
        iifname "wg0" accept

        # Allow established connections back
        ct state established,related accept
    }

    chain output {
        type filter hook output priority 0; policy accept;
    }
}

table inet nat {
    chain postrouting {
        type nat hook postrouting priority 100;

        # NAT traffic from VPN to internet
        oifname != "wg0" ip saddr { 10.10.0.0/24, 10.20.0.0/30 } masquerade
    }
}

Step 1.6: Enable and start services

systemctl enable --now nftables
systemctl enable --now wg-quick@wg0

Step 1.7: Verify

wg show
ip addr show wg0

Phase 2: RU VDS Setup (Gateway)

The main node - handles user connections, DNS-based routing decisions.

Step 2.1: Install packages

apt update && apt install -y wireguard dnsmasq nftables ipset

Step 2.2: Enable IP forwarding

echo 'net.ipv4.ip_forward = 1' >> /etc/sysctl.d/99-vpn.conf
sysctl -p /etc/sysctl.d/99-vpn.conf

Step 2.3: Generate WireGuard keys

mkdir -p /etc/wireguard/keys
chmod 700 /etc/wireguard/keys

# Server key for user-facing interface
wg genkey | tee /etc/wireguard/keys/server.key | wg pubkey > /etc/wireguard/keys/server.pub

# Key for DE tunnel
wg genkey | tee /etc/wireguard/keys/de-tunnel.key | wg pubkey > /etc/wireguard/keys/de-tunnel.pub

chmod 600 /etc/wireguard/keys/*

Step 2.4: Create routing tables

Add to /etc/iproute2/rt_tables:

200 proxy

Step 2.5: Create WireGuard configs

Create /etc/wireguard/wg0.conf (user-facing):

[Interface]
Address = 10.10.0.1/24
ListenPort = 51820
PrivateKey = <RU_SERVER_PRIVATE_KEY>
PostUp = /etc/wireguard/postup.sh
PostDown = /etc/wireguard/postdown.sh

# Users will be added here as [Peer] sections

Create /etc/wireguard/wg1.conf (DE tunnel):

[Interface]
Address = 10.20.0.1/30
PrivateKey = <RU_DE_TUNNEL_PRIVATE_KEY>

[Peer]
# DE VDS
PublicKey = <DE_SERVER_PUBLIC_KEY>
Endpoint = 194.31.173.178:51821
AllowedIPs = 0.0.0.0/0
PersistentKeepalive = 25

Step 2.6: Create PostUp script

Create /etc/wireguard/postup.sh:

#!/bin/bash

# Create ipsets for routing decisions
ipset create direct hash:net -exist
ipset create proxy hash:net -exist

# Add default route via DE tunnel for 'proxy' table
ip route add default via 10.20.0.2 table proxy

# Load nftables rules
nft -f /etc/nftables.conf

Make executable:

chmod +x /etc/wireguard/postup.sh

Step 2.7: Create PostDown script

Create /etc/wireguard/postdown.sh:

#!/bin/bash

# Flush routing table
ip route flush table proxy

# Destroy ipsets
ipset destroy direct 2>/dev/null
ipset destroy proxy 2>/dev/null

# Flush nftables
nft flush ruleset

Make executable:

chmod +x /etc/wireguard/postdown.sh

Step 2.8: Configure nftables

Create /etc/nftables.conf:

#!/usr/sbin/nft -f

flush ruleset

table inet filter {
    chain input {
        type filter hook input priority 0; policy drop;

        # Allow established
        ct state established,related accept

        # Allow loopback
        iif lo accept

        # Allow SSH
        tcp dport 22 accept

        # Allow WireGuard from anywhere (user connections)
        udp dport 51820 accept

        # Allow DNS from VPN clients only
        iifname "wg0" udp dport 53 accept
        iifname "wg0" tcp dport 53 accept

        # Allow ICMP
        icmp type echo-request accept
    }

    chain forward {
        type filter hook forward priority 0; policy drop;

        # Allow forwarding from user VPN
        iifname "wg0" accept

        # Allow forwarding from DE tunnel
        iifname "wg1" accept

        # Allow established
        ct state established,related accept
    }

    chain output {
        type filter hook output priority 0; policy accept;
    }
}

table inet nat {
    chain postrouting {
        type nat hook postrouting priority 100;

        # NAT direct traffic (going out main interface)
        oifname != "wg0" oifname != "wg1" ip saddr 10.10.0.0/24 masquerade
    }
}

table inet mangle {
    chain prerouting {
        type filter hook prerouting priority -150;

        # Mark packets destined for 'proxy' ipset
        ip daddr @proxy meta mark set 0x1
    }
}

Note: nftables native sets will be used instead of ipset. See Step 2.10 for updated approach.

Step 2.9: Configure dnsmasq

Disable systemd-resolved if running:

systemctl disable --now systemd-resolved
rm /etc/resolv.conf
echo "nameserver 8.8.8.8" > /etc/resolv.conf

Create /etc/dnsmasq.d/vpn-routing.conf:

# Listen only on VPN interface
interface=wg0
bind-interfaces

# Upstream DNS
server=8.8.8.8
server=8.8.4.4

# Don't read /etc/resolv.conf
no-resolv

# Cache size
cache-size=10000

# Log queries (optional, disable in production)
# log-queries

# Russian TLDs - route directly (add to 'direct' ipset)
ipset=/ru/direct
ipset=/рф/direct
ipset=/su/direct

# Everything else goes to proxy (default)
# This is handled by routing table, not ipset

Important: dnsmasq's ipset feature requires ipset, not nftables sets. We'll use a hybrid approach.

Step 2.10: Updated routing approach (hybrid ipset + nftables)

Since dnsmasq works with ipset, we'll use ipset for the sets and nftables for the rules.

Update /etc/nftables.conf:

#!/usr/sbin/nft -f

flush ruleset

table inet filter {
    chain input {
        type filter hook input priority 0; policy drop;

        ct state established,related accept
        iif lo accept
        tcp dport 22 accept
        udp dport 51820 accept
        iifname "wg0" udp dport 53 accept
        iifname "wg0" tcp dport 53 accept
        icmp type echo-request accept
    }

    chain forward {
        type filter hook forward priority 0; policy drop;

        iifname "wg0" accept
        iifname "wg1" accept
        ct state established,related accept
    }

    chain output {
        type filter hook output priority 0; policy accept;
    }
}

table inet nat {
    chain postrouting {
        type nat hook postrouting priority 100;

        # NAT direct traffic going out main interface
        oifname != "wg0" oifname != "wg1" ip saddr 10.10.0.0/24 masquerade
    }
}

Update /etc/wireguard/postup.sh:

#!/bin/bash

# Create ipsets
ipset create direct hash:net -exist
ipset flush direct

# Add default route via DE tunnel for 'proxy' table
ip route add default via 10.20.0.2 table proxy 2>/dev/null || true

# Policy routing: packets NOT going to 'direct' ipset use 'proxy' table
ip rule add from 10.10.0.0/24 fwmark 0x1 table proxy priority 100 2>/dev/null || true

# Load nftables
nft -f /etc/nftables.conf

# Add iptables rule for fwmark (nftables mangle is complex with ipset)
iptables -t mangle -A PREROUTING -m set ! --match-set direct dst -s 10.10.0.0/24 -j MARK --set-mark 0x1

Update /etc/wireguard/postdown.sh:

#!/bin/bash

ip rule del from 10.10.0.0/24 fwmark 0x1 table proxy priority 100 2>/dev/null || true
ip route flush table proxy 2>/dev/null || true
iptables -t mangle -F PREROUTING 2>/dev/null || true
ipset destroy direct 2>/dev/null || true
nft flush ruleset

Step 2.11: Enable and start services

systemctl enable --now dnsmasq
systemctl enable --now wg-quick@wg0
systemctl enable --now wg-quick@wg1

Step 2.12: Verify

wg show
ip route show table proxy
ipset list direct

Phase 3: Key Exchange

After generating keys on both servers, exchange public keys:

On DE VDS:

cat /etc/wireguard/keys/server.pub
# Copy this value

On RU VDS:

cat /etc/wireguard/keys/server.pub
cat /etc/wireguard/keys/de-tunnel.pub
# Copy these values

Update configs:

  1. DE VDS /etc/wireguard/wg0.conf: Replace <RU_SERVER_PUBLIC_KEY> with RU's de-tunnel.pub
  2. RU VDS /etc/wireguard/wg1.conf: Replace <DE_SERVER_PUBLIC_KEY> with DE's server.pub

Restart WireGuard:

# On DE VDS
systemctl restart wg-quick@wg0

# On RU VDS
systemctl restart wg-quick@wg1

Verify tunnel:

# On RU VDS
ping 10.20.0.2
wg show wg1

Phase 4: Add First Client

Step 4.1: Generate client keys (on RU VDS)

CLIENT_NAME="phone"
wg genkey | tee /etc/wireguard/keys/client_${CLIENT_NAME}.key | wg pubkey > /etc/wireguard/keys/client_${CLIENT_NAME}.pub
chmod 600 /etc/wireguard/keys/client_${CLIENT_NAME}.*

Step 4.2: Add peer to server

CLIENT_IP="10.10.0.2"
CLIENT_PUBKEY=$(cat /etc/wireguard/keys/client_${CLIENT_NAME}.pub)

wg set wg0 peer ${CLIENT_PUBKEY} allowed-ips ${CLIENT_IP}/32
wg-quick save wg0

Step 4.3: Create client config

CLIENT_NAME="phone"
CLIENT_IP="10.10.0.2"
SERVER_PUBKEY=$(cat /etc/wireguard/keys/server.pub)
CLIENT_PRIVKEY=$(cat /etc/wireguard/keys/client_${CLIENT_NAME}.key)

cat > /etc/wireguard/clients/${CLIENT_NAME}.conf << EOF
[Interface]
PrivateKey = ${CLIENT_PRIVKEY}
Address = ${CLIENT_IP}/32
DNS = 10.10.0.1

[Peer]
PublicKey = ${SERVER_PUBKEY}
Endpoint = 176.124.216.197:51820
AllowedIPs = 0.0.0.0/0
PersistentKeepalive = 25
EOF

mkdir -p /etc/wireguard/clients
chmod 600 /etc/wireguard/clients/${CLIENT_NAME}.conf

Step 4.4: Transfer to client

Display as QR code (for mobile):

apt install -y qrencode
qrencode -t ansiutf8 < /etc/wireguard/clients/${CLIENT_NAME}.conf

Or copy the file contents manually.


Phase 5: Testing

Test 1: Basic connectivity

# From client
ping 10.10.0.1  # Should work - RU VDS
ping 10.20.0.2  # Should work - DE VDS

Test 2: DNS resolution

# From client
nslookup google.com 10.10.0.1
nslookup yandex.ru 10.10.0.1

Test 3: Routing verification

# On RU VDS - check ipset after client visits some .ru sites
ipset list direct

# From client - check external IP
curl ifconfig.me        # Should show DE VDS IP (194.31.173.178)
curl ifconfig.me --resolve ifconfig.me:80:$(dig +short yandex.ru | head -1)  # Won't work, but...

# Better test - check where traffic goes
curl https://2ip.ru    # Russian service, should go direct, show RU VDS IP
curl https://ifconfig.me  # Should show DE VDS IP

Test 4: Check that .ru domains go direct

# From client
traceroute yandex.ru   # Should not go through DE
traceroute google.com  # Should go through DE (you'll see 10.20.0.x hop)

Troubleshooting

WireGuard not connecting

# Check if service is running
systemctl status wg-quick@wg0

# Check for errors
journalctl -u wg-quick@wg0 -e

# Verify port is open
ss -ulnp | grep 51820

DNS not working

# Check dnsmasq
systemctl status dnsmasq
journalctl -u dnsmasq -e

# Test locally
dig @127.0.0.1 google.com

Routing not working

# Check ipset
ipset list direct

# Check routing table
ip route show table proxy
ip rule show

# Check marks
iptables -t mangle -L -v

# Test marking
ping -c 1 8.8.8.8
conntrack -L | grep 8.8.8.8

Traffic not NATed

# Check nftables
nft list ruleset

# Check forwarding
cat /proc/sys/net/ipv4/ip_forward

Summary Checklist

  • DE VDS

    • WireGuard installed
    • IP forwarding enabled
    • Keys generated
    • wg0.conf configured
    • nftables configured
    • Services enabled and started
  • RU VDS

    • WireGuard installed
    • dnsmasq installed
    • ipset installed
    • IP forwarding enabled
    • Keys generated
    • Routing table 'proxy' added
    • wg0.conf configured (users)
    • wg1.conf configured (DE tunnel)
    • postup.sh / postdown.sh created
    • nftables configured
    • dnsmasq configured
    • Services enabled and started
  • Key Exchange

    • DE public key → RU wg1.conf
    • RU de-tunnel public key → DE wg0.conf
    • Tunnel verified (ping 10.20.0.2 from RU)
  • First Client

    • Keys generated
    • Peer added to wg0
    • Client config created
    • Connection tested
    • Routing verified