IPv6 Addresses Explained

A recent study by RIPE (the European Internet Registry for IP addresses) has warned that by 2011 the current version of IP addresses (IPv4) will be depleted, thus it urged all professional bodies and organizations dealing with the Internet to actively adopt and support the new IPv6 address version.

IPv6 addresses are 128 bits long-much longer than the current 32-bit IPv4 address. As we know, the 32-bit IPv4 address scheme supports around 4 billion IP addresses. The new IPv6 version, will support 2 to the 128th power of IP addresses, which is a number that even mathematicians will have a hard time to count!! Continue reading “IPv6 Addresses Explained”

Multimedia Traffic Issues Through a Firewall

Multimedia applications (such as RealAudio, VoIP Telephony, Video Streaming etc) were always an issue when passing through a network firewall. These kind of applications behave in unique ways:

  • They use dynamic ports.
  • They transmit request using TCP and get responses in UDP or TCP.
  • They use the same port for source and destination.
  • For each multimedia request, the multimedia server might send numerous streams of data in reply.

All the above impose an “unacceptable” traffic behavior for a network firewall, thus multimedia traffic needs some special treatment in order to be permitted through the firewall. Continue reading “Multimedia Traffic Issues Through a Firewall”

IANA Well Known Ports

The Well Known Ports are assigned by the IANA and on most systems can only be used by system (or root) processes or by programs executed by privileged users.

Ports are used in the TCP [RFC793] to name the ends of logical connections which carry long term conversations. For the purpose of providing services to unknown callers, a service contact port is defined. This list specifies the port used by the server process as its contact port. The contact port is sometimes called the “well-known port”.

To the extent possible, these same port assignments are used with theĀ  UDP [RFC768].

The range for assigned ports managed by the IANA is 0-1023.

Port Assignments: Continue reading “IANA Well Known Ports”