From 206bb580735d9bb4264d7ced3fca85b0e379fae3 Mon Sep 17 00:00:00 2001
From: alexion <contact@alexion.dev>
Date: Wed, 7 Oct 2026 19:29:20 -0400
Subject: [PATCH] fix(nixos): harden SSH client configuration

---
 configs/nixos/modules/network/ssh.nix | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/configs/nixos/modules/network/ssh.nix b/configs/nixos/modules/network/ssh.nix
index 19e07b5..69c68b3 100644
--- a/configs/nixos/modules/network/ssh.nix
+++ b/configs/nixos/modules/network/ssh.nix
@@ -38,30 +38,27 @@ let
     neogaia = {
       hostName = registry.address.neogaia.self;
       clientKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIGxQ4kWsBo2OGYIPOkFe0vNEcB3yoJwAu0y9wrdQzALE alexion@neogaia";
-      hostKeys = [
-        "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJS+wp7K123+4BT6G4f954R6WyrbWveY7VlpoBUf6I5p neogaia"
-        "ssh-rsa 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 neogaia"
-      ];
+      hostKeys = hostKeysFor "neogaia";
     };
 
     zeus = {
       hostName = registry.address.zeus.self;
       clientKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIIRBcHHuubptXCdvED/p2dR3MpjGN/AimqLasLY5984G alexion@zeus";
-      hostKeys = [
-        "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJ4GBPt966LR4LpmXgiMMkepIqNIlXTUBh4zdNeek/lN root@zeus"
-        "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAACAQC3xOxGAJCG9PE0FVufgJX9VRO64IUUlRGHSOfYfAI4Mit46xKsr7z/OvqPPE9z8rOIcVPbLkc/mkMuHbDgolleunAFCIeuIIYpkL4o4/TZECh9BtN2WdPhjcD7S0rV+rR7p24Qy5bTCSwZmsQq8QxHTVPjjBngtPGRSpKVrZAuHCcdCJ13hBWAvnaav5KysKC89nMj/7FIh02v8kipGfq5LGCZ20Qp2lmv2DS24NhBPXzcw8pLN47I5GYVkZh/0RWOByteo3eXtKCF+JCwfUPCTP+zHGD+1tbO8//B2fkt3Pe9lUrn5eM2ZnX1emXSWfQng3cMqkftzWqvBwv0sSDU+9YV6H2Ury+GrrfukpBtQVe9PQcBWqbRPhxuagncR+af/tx0ZohZS0t74m3WgLtZ4r2mpTZS4oBmRsfvWzMFGSgwtva+3Y+NsLjPPM1Cz5Dn05JJlidzcABfsUg2H23vkmO2otaQI01dUni+szlRn4w6sVyxNcvY2fQGjmt9k7jmVI5D2A3yl+OLJguAAlw3ia335X1tNUG8FoI/VyZNhOckIihmbTtihNIg37Ro4yiuPRhnUWFvg2hcBCa9hzNP7XDUPnoCRQyJ4adQHQA/x4Kh+HJ6pZqtGcdqU80fzmWtrLkWG6v5/NRKs6soYDup7oQIKbJo9TtXvqtzmVmovQ== root@zeus"
-      ];
+      hostKeys = hostKeysFor "zeus";
     };
 
     pikachu = {
       hostName = registry.address.pikachu.self;
       clientKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAINNqJIC6VRXyvrNf3n9su9KdPCikC3CjK/QrCK2reHdB alexion@pikachu";
-      hostKeys = [
-        "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIKljRf4pJO+pqEqjpPz08gOYq3g1PpxvE66xVw7uMEnA root@pikachu"
-        "ssh-rsa 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 root@pikachu"
-      ];
+      hostKeys = hostKeysFor "pikachu";
     };
   };
+  hostKeysFor =
+    host:
+    map builtins.readFile [
+      (../../hosts + "/${host}/ssh_host_ed25519_key.pub")
+      (../../hosts + "/${host}/ssh_host_rsa_key.pub")
+    ];
   workstationNames = [
     "neogaia"
     "zeus"
@@ -206,8 +203,10 @@ in
           owner = user;
         };
 
-        home-manager.users.${user}.programs.ssh.settings."*".IdentityFile =
-          config.sops.secrets.${userKeySecret}.path;
+        home-manager.users.${user}.programs.ssh.settings."*" = {
+          IdentityFile = config.sops.secrets.${userKeySecret}.path;
+          IdentitiesOnly = true;
+        };
       })
     ]
   );