Port 21: International Standard FTP port
This is the port used for all FTP based file transfers, such as with programs like FTP Voyager, WS_FTP, Cute FTP, FTP NOW, and many more (FTP = File Transfer Protocol).
Port 22: International Standard SSH Server Listening port
Port used by Secure Shell servers, SSH, to listen for incoming connections.
Port 23: International Standard Telnet port
The port used by all Telnet applications.
Port 25: International Standard SMTP mail port
Standard port used for SMTP mail delivery. This is the outgoing mail port used by email programs such as Outlook Express, Outlook, FoxMail, and hundreds more, and it is also the SMTP Outgoing port used by mail Servers such as Axigen Mail Server, CMailServer, Lotus Notes, MailEnable, Merak Mail Server, Microsoft Exchange, Novell GroupWise, Qmail, PostCast Server, PostFix, SendMail, SurgeMail, TFS Secure Message Server, WinMail, or any other SMTP / ESMTP standards compliant e-mail MTA (Message Transfer Agent).
Port 42: Microsoft WINS Replication port
Port used to replicate NETBIOS name tables from one Windows Server to another (see port 137 also).
Port 43: International Standard WHOIS port
Port used for "WhoIs" requests (for the retrieval of domain name information) to whois servers.
Port 53: International Standard DNS port for DNS requests & replies
This port is used by clients and Servers when exchanging Domain Name information and routing (DNS = Domain Name Server).
Port 67: International Standard DHCP port for DHCP requests & replies
This is the port used by the DHCP Server and clients when the clients check with the DHCP Server for a new lease and the allocation of an IP address (DHCP = Dynamic Host Configuration Protocol).
Port 79: International Standard Finger command for SMTP Mailservers - ETRN Finger port
Port used by SMTP mail Servers to send ETRN Finger commands to message queues Servers so that those message queues servers know that the mail Servers are online and ready to accept queued up mail. In short: this is the port which your email Server will use to send an ETRN command to your web hosting company’s mail Servers so that they deliver to you any waiting incoming mail.
Port 80: International Standard HTTP port - Internet traffic
The port through which most Internet traffic goes through, through HTTP requests. This is the port which web browsers use to browse the web.
Port 102: International Standard X.400 port
X.400 is one of the earliest standards for communications between Message Handling Systems (MHS) in pre-Internet days. As a result X.400 includes provisions for the network communications to include information about the intended destination medium for the message (e.g., email, fax, telex, etc...). In the Windows world this port is used by default by Microsoft Exchange Server MTAs (Message Transfer Agent) to communicate with each other on internal networks with multiple Exchange servers.
Port 110: International Standard POP3 port
Standard port used for POP3 mail delivery and collection. This is the port normally called the Incoming Mail port in email programs such as Outlook Express, Microsoft Outlook, FoxMail, and others.
Port 115: International Standard SFTP port (Secure File Transfer Protocol)
Port used for FTP file transfers and modifications over a Secure Shell connection (SSH). This is sometimes mistakenly called "FTP over SSH" which it is not—it is actually a completely new file transfer protocol which includes additional features such as error detection, resumption of interrupted transfers, remote file removal, and enumeration (listing) of remote folders and files. Additionally, as the protocol operates within the SSH protocol which secures the connection through authentication and encryption, this protocol has the additional advantage of operating within a secure environment, something which basic FTP lacks totally (passwords and files are sent as clear text which can easily be intercepted and deciphered by snooping programs).
Port 119: International Standard Newsgroups port
Port used for newsgroups access.
Port 123: International Standard Network Time Protocol port (NTP)
Port used for checking and synchronising time with another computer (Time Server). For example, this is the port which Windows XP and Windows Vista use when you configure the clock to automatically synchronize itself with a time server on the Internet. Ditto when you configure a Windows Server to synchronize its time over the Internet.
Port 135: Microsoft RPC Locator Service port
The RPC locator Service (Remote Procedure Call) maintains a list of networked services that support RPC and DCOM standards. This list holds information regarding which ports and IP addresses the services are currently running on or listening on. Thanks to this list, other computers can query this service to find the details needed to connect to a desired RPC service.
Port 137: Microsoft NetBIOS Name service port / WINS
Port used by the NetBIOS protocol to find other computers on a workgroup network. On a Peer to Peer network this will be done via broadcast. If a Windows 2000 server or newer is in place, the discovery of other computers can be done with a centralised database called a WINS server (Windows Internet Naming Service) thereby reducing latency and bandwidth usage on the network. This is analogous to DNS for Internet domain names and Microsoft 2000 / 2003 Domains.
Port 143: International Standard Internet Message Access Protocol 4 (IMAP4 port)
This port is used by IMAP4 servers. IMAP is a method of accessing emails stored remotely on a mail Server (a mailbox). This could be a mailbox at an ISP or a corporate mailserver. IMAP4 is "the other" message access protocol—the first one, and most known, being POP3. IMAP works differently from POP3: the connection to the remote mailbox is constant compared to the Connect-GetMessages-CloseConnection method of POP3. IMAP allows more than one email client to be connected to the same mailbox at the same time—as a direct result it is the protocol of choice for hand-held devices like BlackBerrys as you can have your laptop, desktop PC, and BlackBerry all connected to your mailbox at the same time, something which is not possible with POP3 which requires exclusive access. Another major plus point of IMAP is the ability to retrieve parts of the email, such as the subject only, the message body only, or the attachments only—this is another reason for it being the protocol of choice for devices like BlackBerrys where the user can have the device configured to download and show only the message subjects and when the user decides to open the email in full, then at that point the device requests, specifically, only the body of the message. Last but not least, the IMAP protocol includes the provision of message status flags which let the remote client know whether a message has been read, deleted, replied to, or forwarded—again, this is crucial to BlackBerry-type devices as that is how the IMAP Server can synchronize messages between the device, the server, and any other device simultaneously accessing the same mailbox.
Port 161: International Standard Simple Network Management Protocol (SNMP port)
UDP port used to manage, configure, and gather information about network devices (e.g., Firewalls, Routers) in a unified and uniform manner across a varied range of manufacturers. Most Server operating systems, whether Windows or not, provide support for this protocol. Note: Home and Small office devices tend to use UPnP for this purpose.
Port 179: International Standard Border Gateway Protocol port
The Border Gateway Protocol (BGP) is a routing protocol used to exchange routing information between routers in autonomous networks.
Port 379: Microsoft Site Replication Services (SRS port)
TCP port used by Microsoft Site Replication Services. This service enables LDAP enabled Servers to replicate between each other information stored on Microsoft Active Directory domain Controllers and Exchange Servers.
Port 389: International Standard Lightweight Directory Access Protocol port (LDAP port)
TCP port used to find and manage network resources on hierarchical network systems such as Novell Network Directory Trees (NDS) and Microsoft Active Directory Service Domains.
Port 443: International Standard Secure HTTP traffic port (SSL port)
This is the default port used for SSL encrypted communications (SSL = Secure Socket Layer), such as, for example, when you login to a secure site to purchase something. From a System Administrator’s viewpoint, this is the port that is used for incoming and outgoing SSL connections.
Port 445: International Standard Microsoft Active Directory and SMB Protocol port
This port is used by Microsoft Active Directory services and Microsoft SMB (Server Message Block) protocols. SMB is also known as "Microsoft Windows Network" and is the main protocol used by Microsoft Server Operating Systems for client/Server access, and file and printer sharing.
Port 465: Google Mail Outgoing Mail Server
Google uses this non-standard port for its Outgoing Mail Server for Google Mail. Use this port, smtp.gmail.com, and SSL connection (SMTP Server Authentication) when configuring your email client for Google Mail (GMAIL).
Port 636: International Standard LDAP over SSL
TCP port used for Lightweight Directory Access Protocol over Secure Socket Layer connections. This is a standard added to LDAP to prevent the interception of information and credentials using the LDAP protocol. This standard is used by Microsoft Exchange Server and many other LDAP enabled Server applications (SEE LDAP PORT: 389).
Port 993: International Standard Secure Internet Message Access Protocol port (Secure IMAP port)
TCP Port used for SSL Secured IMAP 4 access (See IMAP4 Port: 143).
Port 995: Google Mail Incoming POP3 Mail Server (GMAIL port)
Google uses this non-standard port for its POP3 Incoming Mail Server for Google Mail (GMAIL). Use this port, pop.gmail.com, and SSL connection when configuring your email client.
Port 1026: Novell Calendar Access Protocol port (CAP) / Windows Services
Port used by Novell GroupWise for its Calendar Access Protocol. Port 1026 is also used by the Windows Task Scheduler or other Windows services.
Port 1080: De-Facto Standard SOCKS / Online Chatting / Hotmail
This port is used mainly by applications such as AOL Instant Messenger for online chatting. It is also used by Hotmail.
Port 1090: De-Facto Standard Real Audio port
Port used by Real Audio video and audio streaming applications.
Port 1433: Microsoft SQL Server Port & SQL Server Replication Port
Used by Microsoft SQL Server 6 and above for SQL replication between SQL servers.
Port 1434: Microsoft SQL Server Monitoring Port
Used by Microsoft SQL Server to monitor SQL server performance.
Port 1521: Oracle Default Oracle port
Default port for connection to an Oracle database server.
Port 1677: Novell GroupWise
Standard port used by Novell GroupWise for TCP/IP communications between clients and agents and the GroupWise Post Office Agent (POA).
Port 1701: International Standard Layer Two Tunnelling Protocol port (L2TP port)
A tunnelling and encryption standard used to connect two Private Business networks together over an Internet connection to create a Virtual Private Network (VPN). This protocol is seen as the replacement to PPTP (port 1723 listed below).
Port 1720: De-Facto Standard H.323 port
Port used for video conferencing equipment which uses the H.323 protocol.
Port 1723: International Standard Point to Point Tunnelling Protocol port (PPTP port)
A tunnelling and encryption standard used to connect two Private Business networks together over an Internet connection (creating one Virtual Private Network). This is the default protocol for establishing a VPN on Windows 2000 Server.
Port 1900: Microsoft Media Center Extender - Xbox 360 port
UDP inbound. Port used by Microsoft’s Xbox 360 when linking to Media Center.
Port 2409: SPAMFighter Content Classification port
UDP inbound and Outbound. Port used by the SPAMFighter software to communicate with its servers in order to determine which emails are spam or not.
Port 3101: Research in Motion Blackberry Enterprise Server (BES) Synchronization Port (BES port)
If you have an outbound firewall, then you will need to open this port (TCP) to enable the Blackberry Enterprise Server to synchronize with the Blackberry devices. Additionally, depending on the configuration of your particular site, you may also need to port forward port 3101 from your router to the Blackberry Enterprise Server.
Port 3306: MySQL AB Default MySQL Port
Default port for connection to a MySQL database server.
Port 3389: Microsoft Remote Desktop Port & Terminal Services Port
TCP Inbound & Outbound. Default port used by Windows XP Remote Desktop Connection and Microsoft Terminal Server for Remote Desktop Connections and/or Terminal Services sessions. For added security it is recommended to change the Remote Desktop port from its default to a value of your choice—this can be changed in the Registry at `HKLM\System\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp\PortNumber` (the "RDP-Tcp" part may have a different name if you renamed your Terminal Server / Remote Desktop connection).
Port 3390: Microsoft Media Center Extender - Xbox 360 port
TCP Inbound. Port used by Microsoft’s Xbox 360 when linking to Media Center.
Port 3535: GoDaddy Secure SMTP Relay port
Port used by GoDaddy customers for email sending using SMTP relay with authentication over any ISP connection via GoDaddy’s Outgoing Mail Server, `smtpout.secureserver.net`. This enables GoDaddy customers to email from anywhere without having to constantly change their email settings to reflect the SMTP Server corresponding to the Internet connection they are using at the time—instead they can email through GoDaddy’s SMTP Relay regardless of where they are.
Port 4321: De Facto Standard RWHOIS port
Port used for "RWhoIs" requests.
Port 4664: Google Desktop Search port
Port used for Google Desktop Search.
Port 5190: America On Line AOL Instant Messenger port
Port used by AIM, the AOL Instant Messenger software.
Port 5500: DualDesk port
Default port used by the DualDesk remote control software.
Port 5631: PCAnywhere 5631 TCP incoming port
Port on which a Symantec PC Anywhere host accepts incoming PC Anywhere connections and then continues to communicate with the remote PC. If you have a PC Anywhere host behind a firewall or firewalled router, then you need to allow (and possibly port forward) incoming TCP connections on this port.
Port 5632: PCAnywhere 5632 UDP incoming port
Port used by Symantec’s PC Anywhere for the streaming of screen updates during a PC Anywhere session. If you have a PC Anywhere host behind a firewall or firewalled router, then you need to allow (and possibly port forward) incoming UDP connections on this port.
Port 5900: RealVNC Default Remote Control Port (De-facto VNC default port)
This is the default RealVNC port for port forwarding to the RealVNC host. You should always change this port from its default as it is a well-known port for all VNC remote control programs and it will therefore be one of the first targets of hackers.
Port 7070: Real Networks Real Streaming Audio port
Port used by Real Networks’ audio streaming servers.
Port 7100: Novell GroupWise
Standard port used by Novell GroupWise for TCP/IP communications between the Message Transfer Agent (MTA) and other agents.
Port 8000: Mirra Inc Mirra Personal Server Communications port
Port used by both the Mirra Client running on the PC, and the Mirra Personal Server, to communicate with each other. This is a TCP port.
Port 8080: International Standard HTTP Internet traffic port
The other port through which HTTP Internet traffic also goes through.
Port 8799: Vodafone UK GPRS Internet Access Proxy port
Port used for GPRS Internet Browsing on the Vodafone UK mobile phone network. If you are on Vodafone you typically need to configure your phone to access the Internet via a proxy on port 8799. The proxy address is: `212.183.137.12:8799`.
Port 8880: De Facto Standard CDDB port
Port used by CD mastering software to communicate with an Internet based CDDB Server for requests about artist and track names.
Port 9100: Google Web Accelerator port
Port used by Google Web Acceleration technology. Google Web Accelerator supports natively only Internet Explorer and FireFox at the time of writing, 2-Sep-2006. Other browsers need to have their HTTP Proxy configured to `127.0.0.1:9100`.
Port 39720: LimeWire communications port
This is the default port which the LimeWire peer-to-peer file-sharing program uses (can be changed by the end-user).