Open Port Check

Open Port Check

Open Port Check

This Open Port Check will serve as a free utility for remotely verifying a port is open or closed. It will be useful for users who wish to check to see if a server is running or a firewall or ISP is blocking certain ports.


Open Port Check

The open port checker is a tool you can use to check domain or your external IP address and detect open ports on your connection. This tool is useful for finding out if your port forwarding is setup correctly or if your server applications are being blocked by a firewall. This tool may also be used as a port scanner to scan your network for ports that are commonly forwarded. It is important to note that some ports, such as port 25, are often blocked at the ISP level in an attempt to prevent malicious activity.

In computer networking, the protocols of the Transport Layer of the Internet Protocol Suite, most notably the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP), but also other protocols, use a numerical identifier for the data structures of the endpoints for host-to-host communications. Such an endpoint is known as a port and the identifier is the port number. The Internet Assigned Numbers Authority (IANA) is responsible for maintaining the official assignments of port numbers for specific uses.

 Domain or IP 

Your IP:

 Optional - Enter custom port number if you cannot find port in dropdown list.

Well-known ports: 0-1023
The following is a list of common ports. During a network security audit, port scans will be perfeormed to determine what network services are available. These services can be on different Operating systems.

Port TCP UDP Description
20 TCP   FTP - Data transfer - File Transfer Protocol
21 TCP   FTP - control (command) File Transfer Protocol
22 TCP UDP SSH - Secure Shell
23 TCP   Telnet protocol-unencrypted text communications
25 TCP   SMTP - Simple Mail Transfer Protocol
43 TCP   WHOIS protocol
53 TCP UDP DNS - Domain Name System
67   UDP DHCP Server - Dynamic Host Configuration Protocol
68   UDP DHCP Client - Dynamic Host Configuration Protocol
70 TCP   Gopher protocol
79 TCP   Finger protocol
80 TCP UDP HTTP - Hypertext Transfer Protocol
109 TCP UDP POP2 - Post Office Protocol 2
110 TCP UDP POP3 - Post Office Protocol 3
115 TCP UDP SFTP - Simple File Transfer Protocol
118 TCP UDP SQL (Structured Query Language) Services
119 TCP UDP NNTP - Network News Transfer Protocol
123 TCP UDP NTP - Network Time Protocol
137 TCP UDP NetBIOS NetBIOS Name Service
138 TCP UDP NetBIOS NetBIOS Datagram Service
143 TCP UDP IMAP - Internet Message Access Protocol
156 TCP UDP SQL Service
161 TCP UDP SNMP - Simple Network Management Protocol
194 TCP UDP IRC - Internet Relay Chat
220 TCP UDP IMAP - Internet Message Access Protocol, version 3
389 TCP UDP LDAP - Lightweight Directory Access Protocol
443 TCP UDP HTTPS - Hypertext Transfer Protocol over SSL/TLS
444 TCP UDP SNPP - Simple Network Paging Protocol
445 TCP UDP SMB (Server Message Block) over TCP
587 TCP UDP SMTP - e-mail message submission
666 TCP UDP Doom, first online first-person shooter
873 TCP UDP rsync file synchronisation protocol
903 TCP UDP VMware Remote Console
993 TCP UDP IMAPS - Internet Message Access Protocol over SSL
995 TCP UDP POP3S - Post Office Protocol 3 over TLS/SSL

Registered ports: 1024-49151
Ports between 1024 and 29151 are known as the Registered Ports. Basically, programs are supposed to register their use of these ports and thereby try to be careful and avoid stomping on each other. Here are some common ports and their programs.

Port TCP UDP Description
1243 TCP UDP SubSeven (Trojan - security risk!)
1352 TCP   IBM Lotus Notes/Domino Remote Procedure Call (RPC) protocol
1433 TCP   MSSQL (Microsoft SQL Server database management system) Server
1494 TCP   Citrix XenApp Independent Computing Architecture (ICA) thin client protocol
1521 TCP   Oracle database default listener, in future releases official port 2483
1604 TCP UDP Citrix ICA / Microsoft Terminal Server
2049   UDP NFS - Network File System
2483 TCP UDP Oracle database listening for unsecure client connections to the listener, replaces port 1521
3306 TCP   MySQL database default listener
5010 TCP UDP Yahoo! Messenger
5190 TCP   AOL Instant Messenger
5632 TCP UDP PCAnywhere
5800 TCP   VNC remote desktop protocol-for use over HTTP
5900 TCP UDP Virtual Network Computing (VNC) remote desktop protocol
6000 TCP UDP X11-used between an X client and server over the network
6699 TCP   Napster
6776 TCP UDP SubSeven (Trojan - security risk!)
7070 TCP UDP RealServer / QuickTime
7778 TCP UDP Unreal Tournament series default server
8080 TCP   HTTP alternate/Web proxy/Caching server/Apache Tomcat
26000 TCP UDP Quake
27010 TCP UDP Half-Life
27960 TCP UDP Quake III
31337 TCP UDP BackOrifice (Trojan - security risk!)

Online Open Port Check Information:

  • Purpose of this Tool : Network Security Audit, Open Port Check
  • Intended Audience : Network Engineers, System Administrators

External Resources: