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Port 1720 Details

known port assignments and vulnerabilities
threat/application/port search:
Port(s) Protocol Service Details Source
1720 tcp h323 Port most commonly used by Microsoft NetMeeting.
H.323 used for voice-over IP call set-up (H.323 Call Control Signalling, IANA official).
IPContact also uses port 1720 (TCP/UDP)

Unspecified vulnerability in the NAT implementation in Cisco IOS 12.1 through 12.4 and 15.0 through 15.1, and IOS XE 3.1.xSG, allows remote attackers to cause a denial of service (device reload) by sending crafted H.323 packets to TCP port 1720, aka Bug ID CSCth11006.
References: [CVE-2011-3277], [BID-49822]
1720 tcp,udp h323hostcall h323hostcall IANA
1503, 1720, 5222, 5223, 7640, 7642, 7648, 7649 tcp applications CUseeMe-CUworld Portforward
1720 tcp applications H.323 Call Setup Portforward
1718-1720 tcp applications H.323 GateKeeper Portforward
1720,15328-15333 tcp applications I2Eye DVC-1000-DVC-1100 Portforward
1720,2500,5901,1766-1767 tcp applications IPContact Portforward
522,389,1503,1720,1731 tcp applications NetMeeting 2.0 through 3.01 (can also use ports 1024-65535 udp) Portforward
1720,5060 tcp applications Polycom ViaVideo H.323 Portforward
1720 tcp H.323/Q.931 Interactive media Nmap
10 records found
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Related ports: 1300  1718  1719  5060  11720  

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External Resources
SANS Internet Storm Center: port 1720

Well Known Ports: 0 through 1023.
Registered Ports: 1024 through 49151.
Dynamic/Private : 49152 through 65535.

TCP ports use the Transmission Control Protocol. TCP is the most commonly used protocol on the Internet and any TCP/IP network. Whereas the IP protocol deals only with packets, TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and that packets will be delivered in the same order in which they were sent. Guaranteed communication/delivery is the key difference between TCP and UDP.

UDP ports use the Datagram Protocol, a communications protocol for the Internet network, transport, and session layers. Like TCP (Transmission Control Protocol), UDP is used with IP (the Internet Protocol) and makes possible the transmission of datagrams from one computer to applications on another computer, but unlike TCP, UDP is connectionless and does not guarantee reliable communication; it's up to the application that received the message to process any errors and verify correct delivery. UDP is often used with time-sensitive applications, such as audio/video streaming, where dropping some packets is preferable to waiting for delayed data.

When troubleshooting unknown open ports, it is useful to find exactly what services/processes are listening to them. This can be accomplished in both Windows command prompt and Linux variants using the "netstat -aon" command. We also recommend runnig multiple anti-virus/anti-malware scans to rule out the possibility of active malicious software. For more detailed and personalized help please use our forums.

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