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--- wireguard [2025/12/03 14:08]
djgalloway [How To]
+++ wireguard [2025/12/17 18:25] (current)
dmick [Mac/Linux]
@@ Line 4: / Line 4: @@
 ===== How To =====
+Overall flow:
+* install Wireguard
+* generate a public/private keypair;
+* send in the public key to David/Dan to get a server entry
+* get an IP address to use in return
+* use the private key, the IP address, and these instructions to configure your
+client
+==== Mac/Linux ==
 . For Mac, Install Wireguard from the App Store\\
@@ Line 10: / Line 20: @@
 For Linux,\\
 <code>
-sudo apt install wireguard-tools
+sudo apt install wireguard-tools resolvconf
 # or
 sudo dnf install wireguard-tools
 </code>
-. Install ''wireguard-tools'' using [[https://brew.sh/|Homebrew]]\\
+For Mac, install ''wireguard-tools'' using [[https://brew.sh/|Homebrew]]\\
 <code>
 brew install wireguard-tools
@@ Line 26: / Line 36: @@
 . Generate a keypair
 <code>
 wg genkey | tee ~/.wireguard/private.key | wg pubkey > ~/.wireguard/public.key
@@ Line 32: / Line 43: @@
 **Keep the Private Key secret!!**
-. Send the public.key contents to David or Dan.  They will update the Wireguard server and give you your VPN IP address.
+. Send the Wireguard public key (''~/.wireguard/public.key'' contents) to David or Dan.  They will update the Wireguard server and give you your VPN IP address.
-. Create ''~/.wireguard/client.conf''\\
+. Create ''~/.wireguard/client.conf''  (note that the $PRIVATE_KEY must expand to
+the actual text of your private key)\\
 <code>
 PRIVATE_KEY=$(cat ~/.wireguard/private.key)
@@ Line 43: / Line 55: @@
 Address = X.X.X.X/32
 DNS = 10.20.192.11, front.sepia.ceph.com, ipmi.sepia.ceph.com
+MTU = 1200
 [Peer]
@@ Line 54: / Line 67: @@
 . Once Dan or David give you your private IP, replace ''X.X.X.X'' in ''client.conf'' with it.
-=== TODO: Linux CLI instructions ===
+. Bring up the interface
-. On Mac OS, open the Wireguard GUI.  Press Command+O and open ''~/.wireguard/client.conf''
+**On Mac OS**, open the Wireguard GUI.  Press Command+O and open ''~/.wireguard/client.conf''.  Click **Activate**
-. Click **Activate**
+Success looks like\\
-Success looks like
 {{::screenshot_2025-12-03_at_9.08.01_am.png?400|}}
+**On Ubuntu**,\\
+<code>
+sudo mkdir -p /etc/wireguard
+sudo mv ~/.wireguard/client.conf /etc/wireguard/wg0.conf
+sudo chmod 600 /etc/wireguard/wg0.conf
+sudo wg-quick up wg0
+</code>
+use wg show to show status.
+==== Windows ====
+.  Install Windows client from https://www.wireguard.com/install/
+. In the wireguard app, select "Add tunnel/Add empty tunnel".  A public and private key will be automatically generated for you.  Note them.  KEEP THE PRIVATE KEY SECRET.
+. send in your public key to David/Dan
+. get an IP address in return
+. add the configuration to the wireguard app.  The first two lines
+([Interface] and PrivateKey = <your private key>) will already be present.
+Be very careful to not change anything besides your Address.  In
+particular, do not edit [Peer] PublicKey; that is the server's public key
+and does not change.
+<code>
+[Interface]
+PrivateKey = <your private key>
+Address = <address from communication with David/Dan>/32
+DNS = 10.20.192.11, front.sepia.ceph.com, ipmi.sepia.ceph.com
+MTU = 1200
+[Peer]
+PublicKey = kyEHy3ZBewI5RiK4/a0/UQn6O1kMt3h8V3u0OwsfUXc=
+AllowedIPs = 172.16.48.0/24, 10.20.192.0/20, 10.20.208.0/20, 172.16.50.0/23, 172.16.53.0/25, 172.16.55.0/26, 172.16.56.0/23, 172.16.59.0/25, 172.16.60.0/25
+Endpoint = 192.86.31.5:1194
+PersistentKeepalive = 25
+</code>
+. Save the configuration, which should activate the wg0 tunnel.  If all goes well, you will see "Latest Handshake" in the Peer section be a few seconds out of date
+. despite DNS = , the current wireguard client does not properly handle split-horizon DNS.  You must add Powershell scripts to the configuration, and enable their execution with a Windows Registry setting.
+Add the following after MTU = in the [Interface] section:
+<code>
+PostUp = powershell -ExecutionPolicy Bypass -File "C:\Wireguard\wg-up.ps1"
+PostDown = powershell -ExecutionPolicy Bypass -File "C:\Wireguard\wg-down.ps1"
+</code>
+and add the scripts to C:\Wireguard:
+<code>
+# wg-up.ps1
+param(
+    [string[]]$Domains = @("sepia.ceph.com", "front.sepia.ceph.com"),
+    [string]$DNSServer = "10.20.192.11"
+)
+# Ensure admin
+if (-not ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator")) {
+    Write-Error "This script must be run as Administrator."
+    exit 1
+}
+# Auto-detect WireGuard interface (by type)
+$Interface = Get-NetAdapter | Where-Object { $_.InterfaceDescription -match "WireGuard" -and $_.Status -eq "Up" } | Select-Object -First 1
+if (-not $Interface) {
+    Write-Error "No active WireGuard interface found."
+    exit 1
+}
+$InterfaceAlias = $Interface.Name
+Write-Output "Using WireGuard interface: $InterfaceAlias"
+# Add NRPT rules (idempotent)
+foreach ($domain in $Domains) {
+    if (-not (Get-DnsClientNrptRule | Where-Object { $_.Namespace -eq $domain })) {
+        Write-Output "Adding NRPT rule for $domain -> $DNSServer"
+        Add-DnsClientNrptRule -Namespace $domain -NameServers $DNSServer
+    }
+}
+# Set connection-specific DNS suffix (short names)
+Set-DnsClient -InterfaceAlias $InterfaceAlias -ConnectionSpecificSuffix $Domains[0]
+Write-Output "Set connection-specific suffix: $($Domains[0])
+</code>
+<code>
+# wg-down.ps1
+param(
+    [string[]]$Domains = @("sepia.ceph.com")
+)
+# Ensure admin
+if (-not ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator")) {
+    Write-Error "This script must be run as Administrator."
+    exit 1
+}
+# Auto-detect WireGuard interface (by type)
+$Interface = Get-NetAdapter | Where-Object { $_.InterfaceDescription -match "WireGuard" -and $_.Status -eq "Up" } | Select-Object -First 1
+if (-not $Interface) {
+    Write-Output "No active WireGuard interface found; skipping cleanup."
+    exit 0
+}
+$InterfaceAlias = $Interface.Name
+Write-Output "Using WireGuard interface: $InterfaceAlias"
+# Remove NRPT rules safely
+foreach ($domain in $Domains) {
+    Get-DnsClientNrptRule |
+        Where-Object { $_.Namespace -eq $domain } |
+        Remove-DnsClientNrptRule -ErrorAction SilentlyContinue
+    Write-Output "Removed NRPT rule for $domain"
+}
+# Clear connection-specific suffix
+Set-DnsClient -InterfaceAlias $InterfaceAlias -ConnectionSpecificSuffix ''
+Write-Output "Cleared connection-specific suffix"
+</code>
+Add to the registry:
+<code>
+HKEY_LOCAL_MACHINE\Software\WireGuard\DangerousScriptExecution
+</code>
+set it to 1.  You can do this with a Command prompt running as administrator:
+<code>
+reg add HKLM\Software\WireGuard /v DangerousScriptExecution /t REG_DWORD /d 1 /f
+</code>
+===== More about DNS Configuration on Linux =====
+If you're using systemd-resolved, stop.  It is incapable of handling split DNS.  I would not use resolvconf.
+The way I (dmick) chose on Fedora 41 was to disable systemd-resolved and set up a dnsmasq instance behind /etc/resolv.conf.  Here's what I did:
+) sudo systemctl stop systemd-resolved; sudo systemctl disable systemd-resolved
+) add this to /etc/systemd/networkd.conf and restart networkd (because I'm running networkd to configure networks):
+<code>
+[Network]
+DynamicUser=no
+ManageResolver=false
+</code>
+) install dnsmasq if necessary, and configure it.  I chose to put my configuration in /etc/dnsmasq.d/dnsmasq.conf (because my system runs dnsmasq with a conf search path of /etc/dnsmasq.d):
+<code>
+# add domain to shortnames in /etc/hosts; may be helpful
+expand-hosts
+# don't use /etc/resolv.conf for servers configured here
+no-resolv
+# for debugging, enable log-queries
+# log-queries
+# set the server that should handle these three domains
+server=/sepia.ceph.com/10.20.192.11
+server=/front.sepia.ceph.com/10.20.192.11
+server=/ipmi.sepia.ceph.com/10.20.192.11
+# set the upstream servers for anything else
+server=1.1.1.1
+server=9.9.9.9
+</code>
+) remove the existing /etc/resolv.conf and replace with this:
+<code>
+nameserver 127.0.0.1
+search front.sepia.ceph.com ipmi.sepia.ceph.com sepia.ceph.com
+options ndots:2
+</code>
+) systemctl restart dnsmasq
+Now lookups of shortname or shortname.front or shortname.ipmi should work.  Note that dig does not respect the search domains in /etc/resolv.conf by default; you must use dig +search <domain>

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