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satellite/hosts/nixos/common/global/openssh.nix
2023-05-28 02:00:10 +02:00

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1.7 KiB
Nix

# This setups a SSH server.
{ outputs, config, lib, ... }:
let
# Record containing all the hosts
hosts = outputs.nixosConfigurations;
# Name of the current hostname
hostname = config.networking.hostName;
# Function from hostname to relative path to public ssh key
pubKey = host: ../../${host}/ssh_host_ed25519_key.pub;
in
{
services.openssh = {
enable = true;
# Forbid root login through SSH.
permitRootLogin = "no";
# Use keys only. Remove if you want to SSH using password (not recommended)
passwordAuthentication = false;
# Automatically remove stale sockets
extraConfig = ''
StreamLocalBindUnlink yes
'';
# TODO: look into what this does
# Allow forwarding ports to everywhere
gatewayPorts = "clientspecified";
# Generate ssh key
hostKeys =
let mkKey = type: path: extra: { inherit type path; } // extra;
in
[
(mkKey "ed25519" "/persist/etc/ssh/ssh_host_ed25519_key" { })
(mkKey "rsa" "/persist/etc/ssh/ssh_host_rsa_key" { bits = 4096; })
];
};
# Passwordless sudo when SSH'ing with keys
security.pam.enableSSHAgentAuth = true;
# Add each host in this repo to the knownHosts list
programs.ssh = {
knownHosts = lib.pipe hosts [
# attrsetof host -> attrsetof { ... }
(builtins.mapAttrs
# string -> host -> { ... }
(name: _: {
publicKeyFile = pubKey name;
extraHostNames = lib.optional (name == hostname) "localhost";
}))
# attrsetof { ... } -> attrsetof { ... }
(lib.attrset.filterAttrs
# string -> { ... } -> bool
(_: { publicKeyFile, ... }: builtins.pathExists publicKeyFile))
];
};
}