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Make UPnP optional for security #339

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Make UPnP optional for security #339

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4de6d28
Make UPnP optional for security
nsekulov Feb 9, 2026
9e99c62
Enable upnp by default
nsekulov Feb 18, 2026
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11 changes: 10 additions & 1 deletion src/csm/Networking/Config/ServerConfig.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,12 +15,14 @@ public class ServerConfig
/// <param name="username">The user name for the hosting player.</param>
/// <param name="password">The optional password for this server.</param>
/// <param name="maxPlayers">The maximum amount of players that can connect to the server.</param>
public ServerConfig(int port, string username, string password, int maxPlayers)
/// <param name="enablePortForwarding">Whether automatic port forwarding (UPnP) should be enabled.</param>
public ServerConfig(int port, string username, string password, int maxPlayers, bool enablePortForwarding)
{
Port = port;
Username = username;
Password = password;
MaxPlayers = maxPlayers;
EnablePortForwarding = enablePortForwarding;
}

public ServerConfig()
Expand All @@ -29,6 +31,7 @@ public ServerConfig()
Username = "";
Password = "";
MaxPlayers = 0;
EnablePortForwarding = true;
}

/// <summary>
Expand All @@ -50,5 +53,11 @@ public ServerConfig()
/// Gets the optional server password.
/// </summary>
public string Password;

/// <summary>
/// Gets whether automatic port forwarding (UPnP) should be enabled.
/// Default is false for security reasons.
/// </summary>
public bool EnablePortForwarding;
}
}
24 changes: 17 additions & 7 deletions src/csm/Networking/Server.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -117,15 +117,25 @@ public bool StartServer(ServerConfig serverConfig)
// First strategy for NAT traversal: Hole punching
SetupHolePunching();

// Second strategy for NAT traversal: Upnp
try
// Second strategy for NAT traversal: Upnp (only if enabled in config)
if (Config.EnablePortForwarding)
{
NatDiscoverer nat = new NatDiscoverer();
nat.DiscoverDeviceAsync().ContinueWith(task => task.Result.CreatePortMapAsync(new Mapping(Protocol.Udp, Config.Port,
Config.Port, "Cities Skylines Multiplayer (UDP)"))).Wait();
AutomaticSuccess = true;
try
{
Log.Info("Attempting automatic port forwarding via UPnP...");
NatDiscoverer nat = new NatDiscoverer();
nat.DiscoverDeviceAsync().ContinueWith(task => task.Result.CreatePortMapAsync(new Mapping(Protocol.Udp, Config.Port,
Config.Port, "Cities Skylines Multiplayer (UDP)"))).Wait();
AutomaticSuccess = true;
Log.Info("Automatic port forwarding successful.");
}
catch (Exception)
{
AutomaticSuccess = false;
Log.Warn("Automatic port forwarding failed. You may need to manually forward port " + Config.Port);
}
}
catch (Exception)
else
{
AutomaticSuccess = false;
}
Expand Down
22 changes: 14 additions & 8 deletions src/csm/Panels/HostGamePanel.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@ public class HostGamePanel : UIPanel

private UICheckBox _passwordBox;
private UICheckBox _rememberBox;
private UICheckBox _portForwardingBox;

private ServerConfig _serverConfig;
private bool _hasRemembered;
Expand All @@ -44,7 +45,7 @@ public override void Start()
color = new Color32(110, 110, 110, 250);

width = 360;
height = 600;
height = 625;
relativePosition = PanelManager.GetCenterPosition(this);

// Title Label
Expand Down Expand Up @@ -78,20 +79,25 @@ public override void Start()
_rememberBox = this.CreateCheckBox("Remember Me", new Vector2(10, -325));
_rememberBox.isChecked = _hasRemembered;

_connectionStatus = this.CreateLabel("", new Vector2(10, -350));
// Port Forwarding box (UPnP)
_portForwardingBox = this.CreateCheckBox("Enable Port Forwarding (UPnP)", new Vector2(10, -350));
_portForwardingBox.isChecked = _serverConfig.EnablePortForwarding;
_portForwardingBox.tooltip = "Automatically forward ports via UPnP.";

_connectionStatus = this.CreateLabel("", new Vector2(10, -375));
_connectionStatus.textAlignment = UIHorizontalAlignment.Center;
_connectionStatus.textColor = new Color32(255, 0, 0, 255);

// Create Local IP Label
_localIp = this.CreateLabel("", new Vector2(10, -380));
_localIp = this.CreateLabel("", new Vector2(10, -405));
_localIp.textAlignment = UIHorizontalAlignment.Center;

// Create External IP Label
_externalIp = this.CreateLabel("", new Vector2(10, -400));
_externalIp = this.CreateLabel("", new Vector2(10, -425));
_externalIp.textAlignment = UIHorizontalAlignment.Center;

// Create VPN IP Label
_vpnIp = this.CreateLabel("", new Vector2(10, -420));
_vpnIp = this.CreateLabel("", new Vector2(10, -445));
_vpnIp.textAlignment = UIHorizontalAlignment.Center;

// Request IP addresses async
Expand All @@ -105,11 +111,11 @@ public override void Start()
};

// Create Server Button
_createButton = this.CreateButton("Create Server", new Vector2(10, -465));
_createButton = this.CreateButton("Create Server", new Vector2(10, -490));
_createButton.eventClick += OnCreateServerClick;

// Close this dialog
_closeButton = this.CreateButton("Cancel", new Vector2(10, -535));
_closeButton = this.CreateButton("Cancel", new Vector2(10, -560));
_closeButton.eventClick += (component, param) =>
{
isVisible = false;
Expand Down Expand Up @@ -165,7 +171,7 @@ private void RequestIPs()
/// </summary>
private void OnCreateServerClick(UIComponent uiComponent, UIMouseEventParameter eventParam)
{
_serverConfig = new ServerConfig(Int32.Parse(_portField.text), _usernameField.text, _passwordField.text, 0);
_serverConfig = new ServerConfig(Int32.Parse(_portField.text), _usernameField.text, _passwordField.text, 0, _portForwardingBox.isChecked);
ConfigData.Save<ServerConfig>(ref _serverConfig, ConfigData.ServerFile, _rememberBox.isChecked);

_connectionStatus.textColor = new Color32(255, 255, 0, 255);
Expand Down