80 WebServer Port 80
When a user types in your IP address or Host Name in the browser, the browser will search for the IP address on port 80 by default for the web pages.

81  WebServer Alternate Port 81
Whenever a user types in your IP address or Host Name in the browser, the browser will look at the IP address on port 80 which is default port and if this Port is blocked, port 81 is used as an alternate port for hosting a website.

21  FTP Server Port 21 
When someone try to connect to your FTP Server, the FTP client will try to establish  connection on Port 21 by default. Thus Port 21 must be open for standard FTP clients to log in and connect to your server.

22  SSH Secure Shell Port 22
If you want to run a SSH Secure Shell then you should keep open port 22 as this port is required for the SSH Client to connect to your server.

23  Telnet Server Port 23
If you run a Telnet server, this port is required for the Telnet Client so that they can connect to your server. In order to use telnet for remote admin and login, port 23 must be open.

25   SMTP Server Port 25
When someone sends a mail message to your SMTP Server, the mail will attempt to come in to your server on Port 25. This is the standard SMTP (Simple Mail Transport protocol) port.

2525  SMTP Alternate Server Port 2525
When someone sends a mail message to your SMTP Server, the mail will attempt to come in to your server on Port 25. Port 2525 is an alternate port used by TZO for the Store and forward services. This is a non-standard port, but useful if the standard SMTP (Simple Mail Transport protocol) port is blocked

110  POP Server Port 110
When you run a mail server, users will typically log into that machine via POP3 (Post Office Protocol) or IMAP4 (Internet Message Access Protocol) to retrieve their mail. POP3 is the most popular protocol for accessing mailboxes.

119   News (NNTP) Server Port 119
When you run a News server, typically News Clients wanting to connect to your news server will connect on port 119. This port needs to be open to run your own news server.

3389   Remote Desktop port 3389
Port 3389 is used for Windows Remote Desktop. If you want to remotely connect to your computer for remote control, using the free XP Remote desktop requires port 3389 to be open.

389  LDAP Server Port 389
LDAP or Lightweight Directory Access Protocol is becoming popular for Directory access, or Name, Telephone, Address directories. For Example LDAP://LDAP.Bigfoot.Com is a LDAP directory server.

143   IMAP4 Server Port 143
IMAP4 or Internet Message Access Protocol is becoming more popular and is used to retrieve Internet Mail from a remote server. It is more disk intensive, since all messages are stored on the server, but it allows for easy online, offline and disconnected use.

443   Secure Sockets Layer (SSL) Server Port 443
When you run a secure server, SSL Clients wanting to connect to your Secure server will connect on port 443. This port needs to be open to run your own Secure Transaction server.

1503 &1720   Microsoft NetMeeting and VOIP Ports 1503 and 1720
MS NetMeeting and other VOIP allows you to host an Internet call or VideoConference with other NetMeeting or VOIP users. NetMeeting is a free product that can be found on the Microsoft Website at http://www.microsoft.com
5631  PCAnywhere Port 5631
When a PCAnywhere server is set up to receive remote requests, it listens on TCP port 5631. This allow you to run a PCAnywhere host and use the Internet to connect back and remotely control your PC.

5900  Virtual Network Computing (VNC) Port 5900
When you run an VNC server to remotely control your PC, it uses port 5900. VNC is very useful if you want to control your server remotely.

Segnala presso: