Порт чекер

Port Checker - Open Port Checker

Port Checker is an online tool which checks a remote computer or device accessibility from the Internet. It can be used to check ports on a remote server. TCP port checker tries to establish TCP connection from our server and if the connection is successful, You should be able to see it.

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Which situations we can check open ports?

Check open ports is possible if your computer's current external IP address. More about this you can ask your ISP. It is worth considering that if your computer is connected to the Internet, instead of directly through the router (the router), the test results are exactly to the router. Check the port status for the computer inside a subnet is possible only with port forwarding.

Frequently Used Ports

Port No.ProtocolDescription
21FTP ControlFile Transfer Protocol - File Transfer Protocol. Port for commands.
22SSHSecure SHell - "secure shell". Remote Management Protocol operating system.
23telnetTErminaL NETwork. Protocol implementation text interface over the network.
25SMTPSimple Mail Transfer Protocol - Simple Mail Transfer Protocol.
43WHOIS"Who is". Protocol obtaining the registration of ownership of domain names and IP addresses
53DNSDomain Name System - Domain Name System.
67DHCPDynamic Host Configuration Protocol - Dynamic Host Configuration Protocol. Dynamic IP
69TFTPTrivial File Transfer Protocol - a simple file transfer protocol.
80HTTP / WebHyperText Transfer Protocol - hypertext transfer protocol.
110POP3Post Office Protocol Version 3 - receive e-mail protocol, version 3
115SFTPSSH File Transfer Protocol. Secure data transmission protocol.
143IMAPInternet Message Access Protocol. Application-level protocol for accessing e-mail.
161SNMPSimple Network Management Protocol - Simple Network Management Protocol. Device Management.
443HTTPSHyperText Transfer Protocol Secure) - protocol HTTP, which supports encryption.
515LPDLine Printer Daemon. Remote printing protocol on the printer.
993IMAP SSLProtocol IMAP, supports SSL encryption.
995POP3 SSLPOP3 protocol supports SSL encryption.
1080SOCKSSOCKet Secure. Receiving protocol secure anonymous access.
3128ProxyCurrently the port often used proxies.
3389RDPRemote Desktop Protocol - Remote Desktop for Windows.
5900VNCVirtual Network Computing - a system of remote access to the desktop computer.
5938TeamViewerTeamViewer - Remote control system for ensuring your computer and data exchange.
8080HTTP / WebAlternate port for the HTTP protocol. Sometimes used proxies.

What is port forwarding?

Port Forwarding is a kind of special configuration on the router, which allows to redirect external requests (from the Internet) to computers or other devices on the local network. In fact it is a way to specify which local computer to send data and connection requests that arrive at a specific port on the router.

Let's say you have a home game or a web server connected to the Internet via a router. All computers connected to the same router are on the same network, so will be able to connect to the server. However, outside of the Internet, connect to your server without port forwarding will not work. If your computer is connected to the Internet directly (without a router / router), then perform port forwarding is required. All your open ports must be accessible from the Internet (of course, if you have a dedicated IP).

How to Test My Firewall

In case you have set up DMZ host and you want to test whether your firewall is effective of not same can also be verified by port checker tool. Use your publich ip and test the ports which you have configured to block from your firewall.

What are ports? What are they used for?

Ports that virtual address on your computer or network device which enables it communicate with other computer or devices. If a program or service plans to work with the network, it opens the port with a unique number, through which it can work with remote clients / servers. In human language it would sound something like this: "I, the server program, open port 1234. If the network cable will come with data port number 1234 - that to me."

Which port numbers can opened?

Ports are identified by numbers from 0 to 65535, inclusive. Any other port can not be opened, respectively, and check too. This limitation TCP / IP protocol. It is worth noting that the client program should always know the port to which it needs to connect to a remote server or another network device. For this reason, the most popular protocols reserved ports in the range from 0 to 1023. For example, carrying out surfing on the Internet, your browser connects to port 80 on a remote server that hosts the site. In response, the browser receives a set of data and code that downloads and displays a web page.

How to close an open port?

First of all it is necessary to remove the cause - a running program or service that opened the port; it is necessary to close / stop. If the open port reason is not clear - Antivirus scan your computer, delete the extra port forwarding rules on the router and set the advanced firewall (Firewall).

Command to check open port in your computer

If you using a Windows or Linux machine, you can easily find open ports or ports which are in use using below commands :

Windows : Start → "cmd" → Run as Administrator → "netstat -bn" Linux : a In the terminal, run the command: "ss -tln"


Port Checker - Open Port

Spend enough time on the internet, and you are bound to stumble upon the term port checker at some point; this is especially true for those individuals with a deep fascination for all things computer related.

Port checker is an online tool, available free for use and particularly effective in finding open ports, open ports that hackers can use to infiltrate your system.


Most computer literate individuals know very little, if anything, about ports; and for good reason. Most computer literate people do not necessarily require intimate knowledge about the internal workings of a computer in order to surf the internet or to utilize their favorite applications.

A port is a virtual address assigned to a computer or network device; this address enables the device in question to communicate with other computers or devices. Ports could be better described as hardware locations through which data transitions in and out.

A computer has internal ports for connecting disk drives, keyboards and the like, as well as external ports used to connect with modems, printers, and other peripheral devices.

For a given program to work with a specific network it must open a port with a unique number; and it is through this port that the program can work with remote clients or servers.

Categories of Ports

There are three categories of ports. Well known ports fall within the range of 0-1023, while registered ports range from 1024 to 49151. Dynamic or private ports are assigned the highest numbers, ranging from 49152 to 65535. IANA (International Assigned Numbers Authority) is the organization responsible for coordinating the use of port numbers, along with domain names and IP address assignments the world over.

Port Forwarding

The capabilities of port checker are particularly useful in the arena of port forwarding, basically simplifying the verification process by allowing individuals to find out if a server is still running or whether certain ports are being blocked by a firewall (or even an ISP).

Also called port mapping, port forwarding is crucial to a remote computer’s ability to connect to a given device or service on a private network. It is a term that speaks of translating the address to a new destination, accepting packets and forwarding them appropriately with the use of a routing table.

Why Port Checker

Port checker is a free online tool; for that reason alone, one has no valid excuse for not to try their hand at all the features it has to offer. More importantly, it is pretty simplistic in design and fairly easy to master.

As per its name, port checker checks open ports on a given device such as a computer. Tiny and portable, it might be more accurate to say that port checker purposes to find out whether a port is open or closed, basing its findings on the data the user inputs.

Admittedly, port checker’s offering of features is limited, but this only further simplifies the learning process; in fact, one hardly requires any noteworthy experience with networking applications to master the capabilities of this utility, port checker designed to be used by anyone that might require its services.


There is no installation required to use the tool; rather the executable file can be dropped to any location on the hard disk and initiated. Port checker can also be saved on a USB flash drive (or any other efficient storage device) and used on any computer you might come across with minimal effort.

Because port checker doesn’t require installation, Windows Registry isn’t updated with new entries; in other words, no files are created on the disk during the operations of port checker, the disk remaining clean after the program has been removed.


Expect to encounter a simple window with a basic structure; it is within this window that you specify the URL or IP address; there is also a drop-down list of port numbers to select from, after which you can click a button, asking the tool to verify whether the port in question is available.

The results are typically immediate, shown in the bottom portion the screen; these results can be cleared any time.

Because port checker utilizes very few resources (processing power and RAM), the performance of the computer will not be affected by its operations.

While it is hardly the most powerful tool for the job, port checker is effective, especially for those individuals facing connection issues with a specific program.


Open Port Check Tool - Open Port

Open Port website is a free Open Port Check Tool to check a remote TCP port state – open or close. The tool can also be use to test your router or device for port forwarding.


Please provide a Hostname and a port number to check, the default that you see are your ip address and the default Http port number 80:

Check other fee tools we have:

Some Well Known Ports

Port Number Description
21 FTP
22 SSH
23 Telnet
53 DNS
110 POP3
135 DCOM (but not only)
1433 MS SQL Server
1521 Oracle Listener
25565 MySQL
For a full list of port numbers refer to Wikipedia – List of TCP and UDP port numbers

Open Port Check Tool:

A port is a number that represent an entry to a service that is open to the network.

There are 65535 ports available to use, some ports had been assigned to special service by INAN (Internet assigned numbers authority).

In networks an open port is a port that currently use by a service, an open port can be use to send or/and receive data.

There are two types of ports, TCP ports and UDP ports, our tool can check the state of TCP port.

This can be done by sending a packet using the Ipv4 (IP version 4) protocol.

An example can be your web browser in the client side and a web server as the remote server.

The web server use the default port 80 for HTTP or port 443 for HTTPS to listen and wait for connections.

Your browser establish a connection to that port, using a local port and once connected they send and receive data between them.

An open port check tool can be use to check if a port is currently open on a target machine, it is like a port test, using this tool can also detect the port forwarding status.

You can also use this tool to remotely check if your server is being blocked by a firewall.

Port Scanner:

A port scanner or port checker is a tool that can be used to scan a range of address or even a network in search for port that are open.

In computer security or hacking it is widely use to search for problematic ports that need to be close or monitor.

An open port is like an open door or a window and with the right knowledge it is possible to use this port to enter into the remote computer.

Using and running a regular port scan is a method to find that ports in the port range and block them.

There are some very useful tools that can be used to scan the network address for open ports, using such tool can even find address inside the organization that need to be removed.

An example to network ports scanner tool is Nmap, using it, you can scan a full subnet, it support several scan methods like the TCP SYN scan and the TCP ACK scan .

Advanced usage of the tool can even detect what is the service (process) that open the port and even the operation system that behind this service.

Online port scanner:

The old art of port scanning is still working, even thou that today there are a lot more security method to close and monitor all the ports in the working environment.

An Intrusion detection system (IDS) can be use to monitor the network.

with the advanced of the web new tools, like an online port scanner develop, using the web as the source to scan an environment..

An online port scanner, is a port scanner like any other port scanner, the only thing in deferent is that it works from outside your network, re: a web site – online.

It is a great tool that can be used to check if you have some unnecessary open ports on your computer/device that needs to be closed.

Port forwarding:

Port forwarding, also known as Port mapping, allows remote devices, like remote computers, to connect to a specific port on a computer (service) in a private network.

This can accomplish by enabling port forwarding on you router and forward a connection on a special port that try to connect your router (you may also need to enable it on your windows firewall or the Unix IP table.

Firewall design for blocking inbound and outbound traffic by closing ports and monitoring the data against malicious activities.

In a basic LAN (local area network) configuration the inner devices have an IP address that is only available inside the LAN, most of the time it start by 10.X or 192.X, the modem/router also have an external IP address that can get out to the internet.

This mean that every device that use the inter net actually use the external IP address to surf the web.

The router/DSL modem know who request the external connection and forward the requested data to that device, this is accomplish automatic by the routers.

Once you or the system administrator enables port forwarding, a device that is outside the LAN will be able to connect into the inner LAN.

This is done by assign a port in the router/modem to forward the incoming data to the relevant inner device on the desire port.

Did You Know:

To check for list of ports that currently open on your host and to see what are the IP addresses or the host that your computer is connected to, you can use the build in command line tool netstat it is one of the build in network tools.


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.

Well-known ports: 0-1023The 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: 1024-49151Ports 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:


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