diff --git a/flake.lock b/flake.lock
index c00847e..73e405c 100644
--- a/flake.lock
+++ b/flake.lock
@@ -7,11 +7,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1619884579,
-        "narHash": "sha256-tkvPHzE5eYhBIqwAIQE0t1K87uh8QhlWmn8F83rSC+s=",
+        "lastModified": 1619907041,
+        "narHash": "sha256-BTvU2QTX1/I+2T9001Jd9f/azzXuVBM58OLLYXEQX3U=",
         "owner": "nix-community",
         "repo": "home-manager",
-        "rev": "614a5b55bf46673c174dd3775e7fb1d6f9e14dfa",
+        "rev": "ca7868dc2977e2bdb4b1c909768c686d4ec0a412",
         "type": "github"
       },
       "original": {
diff --git a/machines/hephaestus/configuration.nix b/machines/hephaestus/configuration.nix
index 8b400c0..fddae6f 100644
--- a/machines/hephaestus/configuration.nix
+++ b/machines/hephaestus/configuration.nix
@@ -15,6 +15,9 @@
   networking.useDHCP = false;
   networking.interfaces.enp34s0.useDHCP = true;
 
+  # Enable the OpenSSH server.
+  services.sshd.enable = true;
+
   services.xserver.videoDrivers = [ "nvidia" ];
 
   # Evolution
diff --git a/main/configuration.nix b/main/configuration.nix
index 04f0872..3c9224f 100644
--- a/main/configuration.nix
+++ b/main/configuration.nix
@@ -9,6 +9,12 @@
     keyMap = "us";
   };
 
+  networking.firewall = {
+    allowPing = false;
+    enable = true;
+    trustedInterfaces = [ "tailscale0" ];
+  };
+
   # Enable the GNOME 3 Desktop Environment.
   services.xserver.enable = true;
   services.xserver.displayManager.gdm.enable = true;