1. Greg Van Dyne December 4, 2007

2. Agenda Introduction Technical Overview Protocols Demonstration Future Trends References

3. Introduction Port Forwarding Opening a port in a router or firewall residing in a private network in order to let a party from the outside world contact a user inside. For example, opening ports for VoIP and videoconferencing traffic makes two-way communications easier no matter which side initiates the call. Also called "port mapping," port forwarding can be done by manual configuration or by software. *definition courtesy of PCWorld.com

4. What is a port? represents an endpoint or "channel" for network communications One computer sends data from port of one IP address to another Port numbers can theoretically range from 0 to 65535 Only one application can be used at a time on any given port Why forward a port? With routers, firewalls prevent direct comm. between IPs Ports

5. A Few Common Ports 21 – FTP 22 – Secure Shell (SSH) 23 – Telnet 80 – HTTP 110 – POP3 mail 3389 – Remote Desktop Protocol (RDP) 6112 – Blizzard’s Battle.net gaming service (Unofficial) *Unofficial – not registered with IANA (Internet Assigned Numbers Authority)

6. Some Familiar Concepts TCP – Transfer Control Protocol - 2 computers directly connect, and remain connected for duration of session *similar to a telephone call UDP – User Datagram Protocol – sends data and relies on devices in between to deliver properly. Not as reliable *like putting mail in mailbox NAT – Network Address Translation – determines destinati0on of packets sent to network. This is where port forwarding comes into play.

8. Static vs. Dynamic IP Static Usually ocnfigured within OS Ensures that internal IP never changes Ports can be forwarded once, and will not require any changes in the future Dynamic Internal IP fluctuates Can cause port forwarding not to work Port Triggering Dynamic port forwarding

9. Port triggering allows for port to to open only when a certain application is running Once application stops, access to that port is turned off Slightly more secure

10. Things to consider The need to forward the packets that come to the router's forwarded port, and the need to rewrite them so that the private machine sees them as originating from the router Only one networked machine can use a specific forwarded port at one time Traditional port forwarding allows the entire world access to the port, thus security is reduced Ports can be changed within registry if unofficial

11. Reverse Port Forwarding Also called reverse tunneling Composed of session server (SS) and session client (SC) SS connects with session port, SC connects with session server component SS tunes in to port that needs forwarded When connection is done, it’s forwarded directly to SC with an accessible destination to that SC Usually needed when a port is behind a router or firewall but that router or firewall is not configurable with normal port forwarding for one reason or another

13. References Cadden, C. (2006) “MP3 Player Market to Reach 286 Million Units by 2010.” In-Stat.com. Retrieved Nov. 23, 2007. http://www.instat.com/press.asp?ID=1648&sku=I N0603155ID. Snell, J. (2004) “How AirTunes Works” Macworld.com. Retrieved Nov. 23, 2007. http://www.macworld.com/weblogs/editors/archi ves/000212.php. Wikipedia. (2007) “Digital Living Network Alliance.” http://en.wikipedia.org/wiki/Digital_Living_Network _Alliance