The designers of the current version of IP, known as IPv4, did not anticipate the explosive growth of the Internet. The 32-bit address space is proving to be too small and restrictive. Firewalls help to reduce this problem, by hiding the addresses of internal network hosts from the Internet. However, this cannot be relied upon as a long-term solution.
Instead, work has been proceeding with a new version of IP, known as IPv6 or IPng (next generation). Besides tackling the addressing issues, IPv6 provides standards for end-to-end encryption of packet payloads, greatly enhancing the security of the Internet. Experimental versions of IPv6 are currently available, but it will be some time before IPv4 is displaced. Nontheless, the encryption facilities of IPv6 are available to IPv4 users in the form of IPSec.