Cisco VPN ports

VPN Ports
As every program on the computer is given a port number so too services that connect to the internet are given port numbers. These port numbers for the various VPN services are dependent on the software and the protocols that are being used.

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PPTP encapsulates packets using GRE- Generic routing protocol which uses IP port 47, The IANA list 1723 as the port for VPN. A common mistake in configuring firewalls for use with PPTP is to open port 1723 and close IP port 47. This allows connections to be established but denies the actual data from passing through the tunnel to the machine. Some software utilities verify if both the ports are open for GRE in PPTP to be used.
L2TP protocol is assigned 115 as its port number.
IPSec VPN ports assignments for uses of Encapsulation Security payload (protocol 50) and Authentication Header (protocol 51). Port 88 for Kerberos authentication in TCP/UDP and port 500 for Internet Security Association and Key Management Protocol in TCP/UDP.
SSL VPN for secure HTTP application uses port 443.
MPLS-in IP uses port 137
For the systems that use VPN hardware normally port 500,4500,10000 &smp 10001 are used. One for outgoing traffic and the other for incoming traffic.

Hardware ports

Hardware ports are an entirely different concept compared to software based network ports. In computer hardware terminology a port is a hardware connection through which the computer communicates with external devices. These are an electrically wired outlet into which and external devices are plugged. These ports come in different shapes and sizes. They connectors we use are called male and female connectors and have standards for its properties and functions. A keyboard is connected to a keyboard port; a printer is connected to the printer port and so on. Plug and play devices are connected to the Universal Serial Bus- USB port. Ports are basically divided into two groups' serial ports and parallel ports. A serial port sends and receives only one bit of data at a time where as parallel ports sends and receives multiple bits over a group of wires.

All processors use assembly instructions to access the ports on the mother board or any add on boards. The methods for mapping these ports are either hardware I/O or memory-mapped I/O. The hardware I/O is a concept where separate numbers are given to the ports and the devices they connect to. Intel processors generally send one byte of instruction/data to the port which is used to gain access to the resources of the processor. In memory-mapped I/O there is not separate numbering for the ports but they are accessed by the processor as if it were another part of the memory of the computer. The number of devices that can be attached to a computer can be increased by various add on cards. These cards use the various bus interfaces available on the motherboard to increase the number of devices attached to a computer. One such card is the Peripheral Component Interconnect-PCI card. A technology to combine hardware ports into a single group to enhance bandwidth and fault tolerance is known as hardware port trunking. This is similar to software port trunking that combines two agents which may be websites or channels.

In the many hardware devices in the VPN market if we hear of number of ports being many these are referring to the number of simultaneous hardware connections that can be made. This enhances the speed and performance of the system especially those of huge enterprises that want video conferencing and voice over the VPN.

VPN ports for network setting is a bit complex when you have no knowledge of the protocols, the encryption and authentication techniques they use. Some software's allow you to configure them properly sometimes you may not be able to configure them properly, for example Microsoft VPN port. When VPN hardware is used for a client the process is easy like that for a Cisco VPN port. For a LAN and huge networks the administrator then has to set privileges and configure the firewall as well. This process is necessary for proper security.

VPN Router: A wise choice for Enterprises
VPN Gateway: Secure Your Network
VPN Firewalls- Stopping Crooks
VPN Tunneling-Safe Passage for Data

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