Networking Overhaul: Modern packets, buffers, handshake, dispatch & security hardening

See Readme

src/game/firewall_manager.h

@@ -0,0 +1,33 @@
+#ifndef __INC_FIREWALL_MANAGER_H__
+#define __INC_FIREWALL_MANAGER_H__
+
+// Kernel-level firewall management.
+// Linux: iptables chains. FreeBSD: ipfw rules.
+// Installs DROP rules for unsolicited UDP and rate-limits TCP SYN floods.
+// Windows: no-op stubs.
+
+class FirewallManager : public singleton<FirewallManager>
+{
+public:
+	FirewallManager();
+	~FirewallManager();
+
+	// Install firewall rules — call after config_init()
+	bool Initialize(WORD gamePort, WORD p2pPort);
+
+	// Remove firewall rules — call during shutdown
+	void Destroy();
+
+private:
+#ifndef OS_WINDOWS
+	bool RunCommand(const char* fmt, ...);
+	void CleanupRules();
+#endif
+
+	std::string m_chainName;	// Linux: iptables chain name
+	int m_ruleBase = 0;			// FreeBSD: ipfw rule number base
+	int m_ruleCount = 0;		// FreeBSD: number of rules installed
+	bool m_initialized = false;
+};
+
+#endif