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Port	Assignment	Blocked (reason blocked)
20	FTP	TCP - Blocked Ports Help , Mountain Cablevision (in order to stop the spread of worms)
23	Telnet	TCP In ITS: Network Blocked Ports , University of New Mexico
25	SMTP	TCP Blocked Ports Help , Mountain Cablevision (because spam and viruses) TCP in/out Ports Blocked or restricted by Cox High Speed Internet , COX Customer Support; Port 25 Blocking , Postcast Server; Does my ISP Block port 25 ? Dreamhost.com AT&T Source: Port 25 Blocking , Postcast Server BellSouth Source: Port 25 Blocking , Postcast Server CableOne Source: Port 25 Blocking , Postcast Server Charter Source: Port 25 Blocking , Postcast Server ATTBI Source: Port 25 Blocking , Postcast Server Earthlink Source: Port 25 Blocking , Postcast Server; Does my ISP Block port 25 ? Dreamhost.com MediaOne Source: Port 25 Blocking , Postcast Server MSN Source: Port 25 Blocking , Postcast Server; Does my ISP Block port 25 ? Dreamhost.com NetZero Source: Port 25 Blocking , Postcast Server Optimum Online Source: Does my ISP Block port 25 ? Dreamhost.com PeoplePC Source: Port 25 Blocking , Postcast Server; Does my ISP Block port 25 ? Dreamhost.com SpryNet Source: Port 25 Blocking , Postcast Server Sympatico.ca Source: Port 25 Blocking , Postcast Server Verio Source: Port 25 Blocking , Postcast Server; Does my ISP Block port 25 ? Dreamhost.com Verizon Source: Port 25 Blocking , Postcast Server TCP In ITS: Network Blocked Ports , University of New Mexico
42		Ports Blocked to Improve Security of Penn State Network , Penn State
69	TFTP	Ports Blocked to Improve Security of Penn State Network , Penn State " (This port was blocked in order to help inhibit the threat of the RPC-DCOM Worm. For more information, please see the following Web sites: http://tms.symantec.com/ and http://isc.sans.org/ ) " UDP In/out ITS: Network Blocked Ports , University of New Mexico
80	HTTP	Blocked Ports Help , Mountain Cablevision (to stop worms that "spread via security holes in web server software") TCP in Ports Blocked or restricted by Cox High Speed Internet , COX Customer Support (because worms) See CP80 Legislative Proposal Control Internet Content by Blocking Port 80
111	SUNRPC	TCP/UDP In/out ITS: Network Blocked Ports , University of New Mexico
135	NetBIOS	NetBIOS Blocked from UCI's Network , UCIrvine " NetBIOS, MS-SQL, lpd, other ports (135, 137-179, 445, 515, 593, 1433, 1434) are blocked at the campus border to protect against scans and certain attacks and worms. "; Ports Blocked to Improve Security of Penn State Network , Penn State "This impacts Microsoft Exchange users from Internet Service Providers outside Penn State attempting to access Penn State Exchange servers. These users are required to use the Penn State Anywhere Virtual Private Network (VPN) service or a dial-up connection ." Blocked Ports , Infinity Internet (TCP Upstream MS Blast and Nachi Worms) UDP in/out Ports Blocked or restricted by Cox High Speed Internet , COX Customer Support (spam, pop ups, worms) TCP/UDP in/out CITIES Firewall: Ports Blocked , University of Illinois TCP/UDP In/out ITS: Network Blocked Ports , University of New Mexico
136	NetBIOS	UDP/TCP in/out Ports Blocked or restricted by Cox High Speed Internet , COX Customer Support (worms, neighbors)
137	NetBIOS	What ports are blocked and why , Chetnet Knowledge Base (inbound UDP) Blocked Ports , Infinity Internet (UDP Upstream MS Blast and Nachi Worms) TCP Blocked Ports Help , Mountain Cablevision(to stop worms) UDP/TCP in/out Ports Blocked or restricted by Cox High Speed Internet , COX Customer Support (worms, neighbors) TCP/UDP in/out CITIES Firewall: Ports Blocked , University of Illinois TCP/UDP In/out ITS: Network Blocked Ports , University of New Mexico NetBIOS Blocked from UCI's Network , UCIrvine; Ports Blocked to Improve Security of Penn State Network , Penn State
138	NetBIOS	Ports Blocked to Improve Security of Penn State Network , Penn State What ports are blocked and why , Chetnet Knowledge Base (inbound UDP) TCP Blocked Ports Help , Mountain Cablevision(to stop worms) UDP/TCP in/out Ports Blocked or restricted by Cox High Speed Internet , COX Customer Support (worms, neighbors) TCP/UDP in/out CITIES Firewall: Ports Blocked , University of Illinois NetBIOS Blocked from UCI's Network , UCIrvine; Ports Blocked to Improve Security of Penn State Network , Penn State
139	NetBIOS	Ports Blocked to Improve Security of Penn State Network , Penn State What ports are blocked and why , Chetnet Knowledge Base (inbound TCP) Blocked Ports , Infinity Internet (TCP Upstream MS Blast and Nachi Worms) TCP Blocked Ports Help , Mountain Cablevision(to stop worms) UDP/TCP in/out Ports Blocked or restricted by Cox High Speed Internet , COX Customer Support (worms, neighbors) TCP/UDP in/out CITIES Firewall: Ports Blocked , University of Illinois TCP/UDP In/out ITS: Network Blocked Ports , University of New Mexico NetBIOS Blocked from UCI's Network , UCIrvine; Ports Blocked to Improve Security of Penn State Network , Penn State
161	SNMP	in CITIES Firewall: Ports Blocked , University of Illinois
162	SNMPTRAP	UDP In ITS: Network Blocked Ports , University of New Mexico
445	Microsoft-DS	NetBIOS Blocked from UCI's Network , UCIrvine Ports Blocked to Improve Security of Penn State Network , Penn State ; What ports are blocked and why , Chetnet Knowledge Base (inbound UDP & TCP) Blocked Ports , Infinity Internet (UDP and TCP Upstream MS Blast and Nachi Worms) TCP in/out Ports Blocked or restricted by Cox High Speed Internet , COX Customer Support (worms, neighbors) TCP/UDP in/out CITIES Firewall: Ports Blocked , University of Illinois TCP/UDP In/out ITS: Network Blocked Ports , University of New Mexico
515		NetBIOS Blocked from UCI's Network , UCIrvine
593		Ports Blocked to Improve Security of Penn State Network , Penn State; What ports are blocked and why , Chetnet Knowledge Base (inbound TCP) TCP In/out ITS: Network Blocked Ports , University of New Mexico
1034		UDP Port Panama reportedly ordered blocked in order to block VoIP
1035		UDP Port Panama reportedly ordered blocked in order to block VoIP
1433	MS-SQL	NetBIOS Blocked from UCI's Network , UCIrvine Ports Blocked to Improve Security of Penn State Network , Penn State What ports are blocked and why , Chetnet Knowledge Base (inbound TCP) TCP in Ports Blocked or restricted by Cox High Speed Internet , COX Customer Support (worms, trojans) TCP In/out ITS: Network Blocked Ports , University of New Mexico
1434	MSSQL	NetBIOS Blocked from UCI's Network , UCIrvine Ports Blocked to Improve Security of Penn State Network , Penn State What ports are blocked and why , Chetnet Knowledge Base (inbound UDP) Blocked Ports , Infinity Internet (UDP Upstream Slammer Worm) UDP in Ports Blocked or restricted by Cox High Speed Internet , COX Customer Support (worms, trojans) In/out CITIES Firewall: Ports Blocked , University of Illinois UDP In/out ITS: Network Blocked Ports , University of New Mexico
1900	MS-DS/NetBios	UDP in/out Ports Blocked or restricted by Cox High Speed Internet , COX Customer Support (worms, trojans)
2002	Cisco Secure Access Control Server	Blocked Ports , Infinity Internet (TCP Upstream vulnerability)
2048	CISCO IOS Webcache	Blocked Ports , Infinity Internet (UDP Upstream vulnerability)
2090		UDP Port Panama reportedly ordered blocked in order to block VoIP
2091		UDP Port Panama reportedly ordered blocked in order to block VoIP
2745		TCP In ITS: Network Blocked Ports , University of New Mexico
3127		TCP In/out ITS: Network Blocked Ports , University of New Mexico
4156		Blocked Ports , Infinity Internet (TCP Upstream created by Linux Slapper worm)
4444		Blocked Ports , Infinity Internet (TCP Upstream created by W32.Blaster.Worm) TCP In/out ITS: Network Blocked Ports , University of New Mexico
5000		UDP Port Panama reportedly ordered blocked in order to block VoIP
5060	SIP	(in order to block VoIP)
5554		Blocked Ports , Infinity Internet (TCP Upstream Sasser Worms )
6346		TCP In ITS: Network Blocked Ports , University of New Mexico
6777		Blocked Ports , Infinity Internet (TCP Upstream BAGEL Worms)
6801		UDP Port Panama reportedly ordered blocked in order to block VoIP
6802		UDP Port Panama reportedly ordered blocked in order to block VoIP
6803		UDP Port Panama reportedly ordered blocked in order to block VoIP
8040		TCP Out ITS: Network Blocked Ports , University of New Mexico
8998		UDP - Blocked Ports , Infinity Internet (Upstream MS SoBIG) UDP In/out ITS: Network Blocked Ports , University of New Mexico
9900		UDP Port Panama reportedly ordered blocked in order to block VoIP
9901		UDP Port Panama reportedly ordered blocked in order to block VoIP
9996		Blocked Ports , Infinity Internet (TCP Upstream Sasser Worms )
10080		TCP In ITS: Network Blocked Ports , University of New Mexico
12080		UDP Port Panama reportedly ordered blocked in order to block VoIP
12120		UDP Port Panama reportedly ordered blocked in order to block VoIP
12122		UDP Port Panama reportedly ordered blocked in order to block VoIP
22555		UDP Port Panama reportedly ordered blocked in order to block VoIP
26133		UDP Port Panama reportedly ordered blocked in order to block VoIP
27374		What ports are blocked and why , Chetnet Knowledge Base (inbound TCP)
30582		UDP Port Panama reportedly ordered blocked in order to block VoIP
35061		UDP Port Panama reportedly ordered blocked in order to block VoIP
38000		UDP Port Panama reportedly ordered blocked in order to block VoIP
38100		UDP Port Panama reportedly ordered blocked in order to block VoIP
38200		UDP Port Panama reportedly ordered blocked in order to block VoIP
41170		in/out CITIES Firewall: Ports Blocked , University of Illinois
47563		UDP Port Panama reportedly ordered blocked in order to block VoIP
48310		UDP Port Panama reportedly ordered blocked in order to block VoIP
51200		UDP Port Panama reportedly ordered blocked in order to block VoIP
51201		UDP Port Panama reportedly ordered blocked in order to block VoIP
56464		UDP In ITS: Network Blocked Ports , University of New Mexico
57375		TCP/UDP In ITS: Network Blocked Ports , University of New Mexico

Notes

Ports are assigned by IANA Internet Port Number Assignments IANA
" Port blocking allows an application to prevent other applications from performing specific binds to the ports within a specified range. " Microsoft Technet Windows TCP/IP Ephemeral, Reserved, and Blocked Port Behavior

Documents

J Postel, NWG RFC 349, Proposed Standard Socket Numbers (May 30, 1972) ("I propose that there be a czar (me ?) who hands out official socket numbers for use by standard protocols. This czar should also keep track of and publish a list of those socket numbers where host specific services can be obtained.")

Links

Arbor Atlas Summary Report: Global Scans (summary of port scans that are taking place)
Port Lookup Utility , Treachery Unlimited (look up what vulnerabilities are associated with different ports)
Trojan List Sorted on Trojan Port Simovitz
Microsoft Technet How to block specific network protocols and ports by using IPSec
Port monitoring http://isc.sans.org/port.html?port=445 Internet Storm Center (replace the number in the URL with the port you want to see a graph for)
SANS Institute - Intrusion Detection FAQ: What Port Numbers do well-known Trojan horses use ?

Network Ports Policies

Network access disabled by the University (Internet and port blocks) , Yale University ITS (list of blocked ports is password protected)
BYU IT Blocked Ports (lots)
" All Internet ports not needed for Internet browsing and simple email communications are blocked. " - Community Wireless Internet Town of Amherst , Massachusetts

Port Scanners

Port Authority Database (probe individual ports)
Mantid : Web-Based Discriminatory Port Blocking Measurement, MIT

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