What Is a Free Port?

"Port" is a free translation of English port, which can be considered as an outlet for communication between the device and the outside world. Ports can be divided into virtual ports and physical ports, where virtual ports refer to ports inside the computer or inside the switch router and are not visible. For example, 80 ports, 21 ports, 23 ports, etc. in the computer. Physical ports are also called interfaces, which are visible ports, RJ45 network ports on computer backplanes, RJ45 ports such as switch router hubs. The use of RJ11 jacks for phones also belongs to the category of physical ports.

Port is

If you compare an IP address to a house, the port is the door to and from the house. The real house has only a few doors, but there can be as many as 65536 (ie: 2 ^ 16) ports for an IP address! Port is through

We know that a host with an IP address can provide many services, such as

Friends who are new to the Internet are generally very sensitive to their own ports. They are always afraid that their computers have too many ports open, and they are even more afraid of having backdoor ports. Lift up the net to feel nervous. In fact, protecting your own port is not that difficult, just do the following:

1) View: often use commands or software to check the ports open locally to see if there are suspicious ports;

2) Judgment: If you are unfamiliar with the open ports, you should immediately find the port encyclopedia or common ports such as Trojans (there are many on the Internet), and look at the description of the role of your suspicious port, or open this through software viewing Port process to make judgments;

3) Close: If it is really a Trojan port or there is no description of this port in the information, then this port should be closed. You can block this port with a firewall

For more information, see the IANA website ^[2]

Some ports are often used by hackers and by some Trojan horses to attack computer systems. The following are

In simple terms, the methods of illegal intrusion can be roughly divided into 4 types:

1. Scan the port and break into the host through known system bugs.

2. Plant Trojans and use the back door opened by the Trojans to enter the host.

3. Use data overflow to force the host to provide a backdoor to enter the host.

4. Take advantage of certain software design vulnerabilities to directly or indirectly control the host.

The main methods of illegal intrusion are the first two, especially using some popular

Active Directory port and protocol requirements

Application servers, client computers, and domain controllers in a public or external forest have service dependencies to allow user and computer-initiated operations such as domain join, logon authentication, remote management, and Active Directory replication to work jobs. Such services and operations require network connectivity through specific ports and network protocols.

A comprehensive list of services, ports, and protocols required for member computers and domain controllers to interoperate or for application servers to access Active Directory includes, but is not limited to, the following:

Citing Active Directory-Dependent Services

Active Directory / LSA

Computer browser

Distributed file system

File Copy Service

Kerberos Key Distribution Center

Network login

Remote Procedure Call (RPC)

server

Simple Mail Transfer Protocol (SMTP) (if configured)

WINS (in Windows Server 2003 SP1 and later versions for backing up Active Directory replication operations if DNS does not work)

Windows time

World Wide Web Publishing Service

Services that require Active Directory services

Certificate Services (required for specific configurations)

DHCP server (if configured)

Distributed file system

Distributed Link Tracking Server (optional, but will be selected by default on Windows 2000 computers)

Distributed transaction coordinator

DNS server

Fax service (if configured)

File copy service.

Macintosh file server (if configured).

Internet authentication service (if configured).

License record (used by default).

Network login

Spooler.

Remote installation (if configured).

Remote procedure call (RPC) locator.

Remote storage notifications.

Remote storage server.

Routing and remote access

server.

Simple Mail Transfer Protocol (SMTP) (if configured)

terminal service

Terminal Services Licensing.

Terminal Services session directory.

To open the port:

Control Panel-windows firewall-exception-open the port you want to open or add another port you want to add.