diff --git a/ops/nixos/lib/home-manager/ext.nix b/ops/nixos/lib/home-manager/ext.nix
new file mode 100644
index 0000000000..d87b549992
--- /dev/null
+++ b/ops/nixos/lib/home-manager/ext.nix
@@ -0,0 +1,17 @@
+{ config, lib, pkgs, ... }:
+
+let
+  caKnownHostsFile = pkgs.writeText "ca-known-hosts" ''
+    @cert-authority * ${builtins.readFile ../../../secrets/server-ca.pub}
+  '';
+in {
+  programs.ssh = {
+    extraConfig = ''
+      CanonicalizeHostname yes
+      CanonicalDomains int.as205479.net as205479.net
+      CanonicalizeMaxDots 0
+      CanonicalizePermittedCNAMEs *.lukegb.com:*.as205479.net,*.int.as205479.net *.lukegb.dev:*.as205479.net,*.int.as205479.net *.zxcvbnm.ninja:*.as205479.net,*.int.as205479.net
+    '';
+    userKnownHostsFile = "~/.ssh/known_hosts ${caKnownHostsFile}";
+  };
+}
diff --git a/ops/nixos/lib/home-manager/porcorosso-wsl.nix b/ops/nixos/lib/home-manager/porcorosso-wsl.nix
index 7f42fc1273..04afafaab5 100644
--- a/ops/nixos/lib/home-manager/porcorosso-wsl.nix
+++ b/ops/nixos/lib/home-manager/porcorosso-wsl.nix
@@ -1,6 +1,6 @@
 { pkgs, depot, lib, config, ... }:
 {
-  imports = [ ./graphical-client-wayland.nix ];
+  imports = [ ./graphical-client-wayland.nix ./ext.nix ];
 
   config = {
     programs.keychain = {