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Port 110 Details

known port assignments and vulnerabilities
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Port(s) Protocol Service Details Source
110 udp pop-or-not POP3 server traffic (should be TCP only?)

Final Fantasy XI also uses this port.
110 tcp POP3 POP3 (Post Office Protocol - Version 3)

Security Concerns: Re-usable cleartext password, no auditing of connections & attempts thus subject to grinding. Some POP3 server versions have had buffer overflow problems. CERT Advisories: CA-97.09

ADM, ProMail trojans also use port 110 (TCP).

Integer overflow in inetcomm.dll in Microsoft Outlook Express 5.5 SP2, 6, and 6 SP1; Windows Live Mail on Windows XP SP2 and SP3, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7; and Windows Mail on Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7 allows remote e-mail servers and man-in-the-middle attackers to execute arbitrary code via a crafted (1) POP3 or (2) IMAP response, as demonstrated by a certain +OK response on TCP port 110, aka "Outlook Express and Windows Mail Integer Overflow Vulnerability."
References: [CVE-2010-0816] [BID-40052]

Integer overflow in eXtremail 2.1.1 and earlier allows remote attackers to cause a denial of service, and possibly execute arbitrary code, via a long USER command containing "%s" sequences to the pop3 port (110/tcp), which are expanded to "%%s" before being used in the memmove function, possibly due to an incomplete fix for [CVE-2001-1078].
References: [CVE-2007-5467] [BID-26074] [SECUNIA-27220]

The POP3 service in YahooPOPs (aka YPOPs!) 1.6 allows a remote denial of service (reboot) via a long string to TCP port 110, a related issue to CVE-2004-1558.
References: [CVE-2024-24736]
110 tcp Post Office Protocol 3 (POP3) (official) Wikipedia
110 tcp trojan ADM worm Trojans
110 tcp,udp pop-3 PostOffice V.3 SANS
110 tcp ProMailtrojan [trojan] ProMail trojan SANS
110 tcp,udp applications POP3 Portforward
110 tcp,udp pop3 PostOffice V.3 Nmap
110 tcp threat Bancos Bekkoame
110 tcp threat Civcat Bekkoame
110 tcp,udp pop3 Post Office Protocol - Version 3 IANA
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Related ports: 25  443  25  109  143  587  993  995  

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External Resources
SANS Internet Storm Center: port 110

Port numbers in computer networking represent communication endpoints. Ports are unsigned 16-bit integers (0-65535) that identify a specific process, or network service. IANA is responsible for internet protocol resources, including the registration of commonly used port numbers for well-known internet services.
Well Known Ports: 0 through 1023.
Registered Ports: 1024 through 49151.
Dynamic/Private : 49152 through 65535.

TCP ports use the Transmission Control Protocol, the most commonly used protocol on the Internet and any TCP/IP network. 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. Like TCP, UDP is used in combination with IP (the Internet Protocol) and facilitates 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 and realtime gaming, 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.

Please use the "Add Comment" button below to provide additional information or comments about port 110.
  User Reviews/Comments:
by elisamartin08 - 2020-03-12 04:16
Thank you for the sharing good knowledge and information its very helpful and understanding.. as we are looking for this information since long time. Aol Error Code 691
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