diff --git a/src/IPAddr.h b/src/IPAddr.h
new file mode 100644
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--- /dev/null
+++ b/src/IPAddr.h
@@ -0,0 +1,162 @@
+
+#ifndef IPADDR_H
+#define IPADDR_H
+
+/// Class storing both IPv4 and IPv6 addresses.
+class IPAddr
+{
+public:
+	/// Address family.
+	enum { IPv4, IPv6 } Family;
+
+	/// Byte order.
+	enum { Host, Network } ByteOrder;
+
+	/// Constructs an address instance from an IPv4 address.
+	///
+	/// @param in6 The IPv6 address.
+	IPAddr(const in4_addr& in4);
+
+	/// Constructs an address instance from an IPv6 address.
+	///
+	/// @param in6 The IPv6 address.
+	IPAddr(const in6_addr& in6);
+
+	/// Constructs an address instance from a string representation.
+	///
+	/// @param s String containing an IP address as either a dotted IPv4
+	/// address or a hex IPv6 address.
+	IPAddr(const string& s);
+
+	/// Constructs an address instance from a string representation.
+	///
+	/// @param s String containing an IP address as either a dotted IPv4
+	/// address or a hex IPv6 address.
+	IPAddr(const BroString& s);
+
+	/// Constructs an address instance from a raw byte representation.
+	///
+	/// @param family The address family.
+	///
+	/// @param bytes A pointer to the raw byte representation. This must point
+	/// to 4 bytes if \a family is IPv4, and to 16 bytes if \a family is
+	/// IPv6.
+	///
+	/// @param order Indicates whether the raw representation pointed to
+	/// be \a bytes is stored in network or host order.
+	IPAddr(Family family, const u_char* bytes, ByteOrder order);
+
+	/// Copy constructor.
+	IPAddr(const IPAddr& other);
+
+	/// Destructor.
+	~IPAddr();
+
+	/// Returns the address' family.
+	Family family() const;
+
+	/// Returns true if the address represents a loopback device.
+	bool IsLoopback() const;
+
+	/// Returns true if the address represents a multicast address.
+	bool IsMulticast() const;
+
+	/// Returs true if the address represents a broadcast address.
+	bool IsBroadcast() const;
+
+	/// Retrieves the raw byte representation of the address.
+	///
+	/// @param bytes The pointer to which \a bytes points will be set to
+	/// the address of the raw representation. The return value indicates
+	/// how many bytes are valid starting at that address. The pointer
+	/// will be valid as long as the address instance exists.
+	///
+	/// @return The number of bytes the raw representation uses. This
+	/// will be 4 for an IPv4 address and 32 for an IPv6 address. 
+	int GetBytes(unsigned u_char** bytes); // Returns network-byte order.
+
+	/// Masks out lower bits of the address.
+	///
+	/// @param top_bits_to_keep The number of bits \a not to mask out,
+	/// counting from the highest order bit. The value is always
+	/// interpreted relative to the IPv6 bit width, even if the address
+	/// is IPv4. That means if compute ``192.168.1.2/16``, you need to
+	/// pass in 112 (i.e., 96 + 16). The value must be in the range from
+	/// 0 to 128.
+	void Mask(int top_bits_to_keep);
+
+	/// Assignment operator.
+	const IPAddr& operator=(const IPAddr& other);
+
+	/// Returns a string representation of the address. IPv4 addresses
+	/// will be returned in dotted representation, IPv6 addresses in
+	/// compressed hex.
+	operator string() const;
+
+private:
+	struct in6_addr in6; // This stored IPv6 addresses via the standard v4-to-v6 mapping.
+};
+
+/// Comparision operator for IP addresss.
+extern bool operator==(const IPAddr& addr1, const IPAddr& addr2) const;
+
+/// Comparision operator IP addresses. This defines a well-defined order for
+/// IP addresses. However, the order does not necessarily correspond to their
+/// numerical values.
+extern bool operator<(const IPAddr& addr1, const IPAddr& addr2) const;
+
+/// Class storing both IPv4 and IPv6 prefixes (i.e., \c 192.168.1.1/16 and \c FD00::/8.
+class IPPrefix
+{
+public:
+	/// Constructs a prefix instance from an IPv4 address and a prefix
+	/// length.
+	///
+	/// @param addr The IPv4 address.
+	///
+	/// @param length The prefix length in the range from 0 to 32.
+	IPPrefix(const in4_addr& in4, uint16_t length);
+
+	/// Constructs a prefix instance from an IPv6 address and a prefix
+	/// length.
+	///
+	/// @param addr The IPv6 address.
+	///
+	/// @param length The prefix length in the range from 0 to 128.
+	IPPrefix(const in6_addr& in6, uint16_t length);
+
+	/// Copy constructor.
+	IPPrefix(const IPPrefix& other);
+
+	/// Destructor.
+	~IPPrefix();
+
+	/// Returns the prefix in the form of an IP address. The address will
+	/// have all bits not part of the prefixed set to zero.
+	const IPAddr& Prefix() const;
+
+	/// Returns the bit length of the prefix.
+	uint16_t Length() const;
+
+	/// Assignment operator.
+	const IPPrefix& operator=(const IPPrefix& other);
+
+	/// Returns a string representation of the prefix. IPv4 addresses
+	/// will be returned in dotted representation, IPv6 addresses in
+	/// compressed hex.
+	operator string() const;
+
+private:
+	IPAddr prefix;	// We store it as an address with the non-prefix bits masked out via Mask().
+	uint16_t mask;	// The bit length.        
+};
+
+/// Comparision operator for IP prefix.
+extern bool operator==(const IPPrefix& net1, const IPPrefix& net2) const;
+
+/// Comparision operator IP prefixes. This defines a well-defined order for
+/// IP prefix. However, the order does not necessarily corresponding to their
+/// numerical values.
+extern bool operator<(const IPPrefix& net1, const IPPrefix& net2) const;
+
+#endif