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Port 27015 Details


known port assignments and vulnerabilities
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Port(s) Protocol Service Details Source
27015 tcp steam GoldSrc and Source engine dedicated server port

Ports 27000 to 27040 are typically used by online games.

Steam (Valve gaming platform) uses these ports:
27000-27015 udp (Steam client game client traffic)
27015-27030 tcp/udp (typically matchmaking and HLTV, also used to download Steam content)
27031 udp, 27036 tcp/udp, and 27037 tcp (incoming for in-home streaming)
3478 udp, 4379 udp, 4380 udp (outbound - Steamworks P2P networking and voice chat)
4380 udp (Steam client)

Games:
Half-Life and its mods, such as Counter-Strike
Empire: Total War (The Creative Assembly)
Left 4 Dead (Valve Corporation)
Team Fortress 2 (Valve Corporation)
SG
27015 udp applications Ports 27000 to 27040 are typically used by some online games.

Steam (Valve gaming platform) uses these ports:
27000-27015 udp (Steam client game client traffic)
27015-27030 tcp/udp (typically matchmaking and HLTV, also used to download Steam content)
27031 udp, 27036 tcp/udp, and 27037 tcp (incoming for in-home streaming)
3478 udp, 4379 udp, 4380 udp (outbound - Steamworks P2P networking and voice chat)
4380 udp (Steam client)

The SV_CheckForDuplicateNames function in Valve Software Half-Life CSTRIKE Dedicated Server 1.6 and earlier allows remote authenticated users to cause a denial of service (infinite loop and daemon hang) via a backslash character at the end of a connection string to UDP port 27015.
References: [CVE-2006-0734] [BID-16619]

The SV_CheckForDuplicateNames function in Valve Software Half-Life CSTRIKE Dedicated Server 1.1.1.0 and earlier allows remote authenticated users to cause a denial of service (infinite loop and daemon hang) via a certain connection string to UDP port 27015 that represents "absence of player informations," a related issue to CVE-2006-0734.
References: [CVE-2003-1325]

Call of Duty: Modern Warfare is vulnerable to a denial of service, caused by an error in the online multiplayer functionality. By sending a specially-crafted datagram to UDP port 27015, a remote attacker could exploit this vulnerability to cause the server to crash.
References: [XFDB-80011], [BID-56475], [SECUNIA-51280]
SG
27015 tcp,udp Half-Life and its mods, such as Counter-Strike (unofficial) Wikipedia
27015 udp halflife Half-Life Game Server SANS
1200,27000-27015 udp applications Counter Strike Portforward
27015-27020 udp applications Dark Messiah of Might and Magic Steam Client Portforward
27015 tcp applications Dark Messiah of Might and Magic Steam Client Portforward
1200,27000-27015 udp applications Day of Defeat Source Portforward
6003, 7002, 27010, 27015, 27025 udp applications Half Life Portforward
1200,27000-27015 udp applications Half Life 2 Steam Portforward
27015,27020 udp applications Half Life 2 Steam Server Portforward
1200,27000-27015 udp applications Half Life Steam Portforward
27015,27020 udp applications Half Life Steam Server Portforward
27015 tcp,udp applications Rag Doll Kung Fu Server Portforward
27015 tcp applications Steam Server Portforward
27015 udp halflife Half-life game server Nmap
27000-27050 tcp,udp games Ports 27000 to 27050 are typically used by some online games.

Steam (Valve gaming platform) uses these ports:
27000-27015 udp (Steam client game client traffic)
27015-27030 tcp/udp (typically matchmaking and HLTV, also used to download Steam content)
27031 udp, 27036 tcp/udp, and 27037 tcp (incoming for in-home streaming)
3478 udp, 4379 udp, 4380 udp (outbound - Steamworks P2P networking and voice chat)
4380 udp (Steam client)
SG
27010-27344 tcp,udp Unassigned. "Unauthorized Use Known on ports 27017 IANA
18 records found
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Related ports: 27010  27014  27017  27020  49181  

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External Resources
SANS ISC: port 27015

Notes:
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 27015.
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by UnicornsRock - 2018-01-06 02:57
I have reason to believe from observational evidence the game "7 Days to Die" may belong on that list too.

Until enabling port forwarding on our firewall's NAT rules for tcp:27015 to our gaming VM, users connecting to our "7 Days to Die" server were prone to portscan temporary bans under Snort.

Enabling this port for the time being appears to have resolved the issue.
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