Network: Auto-kick clients after too many failed rcon/settings attempts

src/network/network_server.cpp

@@ -1039,9 +1039,12 @@ NetworkRecvStatus ServerNetworkGameSocketHandler::Receive_CLIENT_SETTINGS_PASSWO
 		DEBUG(net, 0, "[settings-ctrl] wrong password from client-id %d", this->client_id);
 		NetworkServerSendRcon(this->client_id, CC_ERROR, "Access Denied");
 		this->settings_authed = false;
+		NetworkRecvStatus status = this->HandleAuthFailure(this->settings_auth_failures);
+		if (status != NETWORK_RECV_STATUS_OKAY) return status;
 	} else {
 		DEBUG(net, 0, "[settings-ctrl] client-id %d", this->client_id);
 		this->settings_authed = true;
+		this->settings_auth_failures = 0;
 	}
 
 	return this->SendSettingsAccessUpdate(this->settings_authed);
@@ -1592,7 +1595,7 @@ NetworkRecvStatus ServerNetworkGameSocketHandler::Receive_CLIENT_RCON(Packet *p)
 
 	if (_settings_client.network.rcon_password.empty()) {
 		NetworkServerSendRcon(this->client_id, CC_ERROR, "Access Denied");
-		return NETWORK_RECV_STATUS_OKAY;
+		return this->HandleAuthFailure(this->rcon_auth_failures);
 	}
 
 	std::vector<byte> password = p->Recv_buffer();
@@ -1601,7 +1604,7 @@ NetworkRecvStatus ServerNetworkGameSocketHandler::Receive_CLIENT_RCON(Packet *p)
 	if (password != this->rcon_password_hash_cache.GetHash(_settings_client.network.rcon_password, this->rcon_hash_bits)) {
 		DEBUG(net, 0, "[rcon] wrong password from client-id %d", this->client_id);
 		NetworkServerSendRcon(this->client_id, CC_ERROR, "Access Denied");
-		return NETWORK_RECV_STATUS_OKAY;
+		return this->HandleAuthFailure(this->rcon_auth_failures);
 	}
 
 	DEBUG(net, 3, "[rcon] Client-id %d executed: %s", this->client_id, command.c_str());
@@ -1609,6 +1612,7 @@ NetworkRecvStatus ServerNetworkGameSocketHandler::Receive_CLIENT_RCON(Packet *p)
 	_redirect_console_to_client = this->client_id;
 	IConsoleCmdExec(command.c_str());
 	_redirect_console_to_client = INVALID_CLIENT_ID;
+	this->rcon_auth_failures = 0;
 	return NETWORK_RECV_STATUS_OKAY;
 }
 
@@ -1638,6 +1642,17 @@ NetworkRecvStatus ServerNetworkGameSocketHandler::Receive_CLIENT_MOVE(Packet *p)
 	return NETWORK_RECV_STATUS_OKAY;
 }
 
+NetworkRecvStatus ServerNetworkGameSocketHandler::HandleAuthFailure(uint &failure_count)
+{
+	failure_count++;
+	if (_settings_client.network.max_auth_failures != 0 && failure_count >= _settings_client.network.max_auth_failures) {
+		DEBUG(net, 0, "Kicked client-id #%d due to too many failed authentication attempts", this->client_id);
+		return this->SendError(NETWORK_ERROR_KICKED);
+	} else {
+		return NETWORK_RECV_STATUS_OKAY;
+	}
+}
+
 const char *ServerNetworkGameSocketHandler::GetClientStatusName(ClientStatus status)
 {
 	static const char* _client_status_names[] {

src/network/network_server.h

@@ -100,6 +100,9 @@ public:
 	uint desync_frame_seed = 0;
 	uint desync_frame_state_checksum = 0;
 
+	uint rcon_auth_failures = 0;
+	uint settings_auth_failures = 0;
+
 	ServerNetworkGameSocketHandler(SOCKET s);
 	~ServerNetworkGameSocketHandler();
 
@@ -131,6 +134,8 @@ public:
 	NetworkRecvStatus SendConfigUpdate();
 	NetworkRecvStatus SendSettingsAccessUpdate(bool ok);
 
+	NetworkRecvStatus HandleAuthFailure(uint &failure_count);
+
 	std::string GetDebugInfo() const override;
 
 	static void Send();

src/settings_type.h

@@ -383,6 +383,7 @@ struct NetworkSettings {
 	std::string network_id;                               ///< network ID for servers
 	std::string company_password_storage_token;           ///< company password storage token
 	std::string company_password_storage_secret;          ///< company password storage secret
+	uint8       max_auth_failures;                        ///< maximum auth failures before client is kicked
 	bool        autoclean_companies;                      ///< automatically remove companies that are not in use
 	uint8       autoclean_unprotected;                    ///< remove passwordless companies after this many months
 	uint8       autoclean_protected;                      ///< remove the password from passworded companies after this many months

src/table/settings/network_settings.ini

@@ -256,3 +256,11 @@ var      = network.reload_cfg
 flags    = SF_NOT_IN_SAVE | SF_NO_NETWORK_SYNC | SF_NETWORK_ONLY
 def      = false
 cat      = SC_EXPERT
+
+[SDTC_VAR]
+var      = network.max_auth_failures
+type     = SLE_UINT8
+flags    = SF_NOT_IN_SAVE | SF_NO_NETWORK_SYNC | SF_NETWORK_ONLY
+def      = 10
+min      = 0
+max      = 255