Networking Tips


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Reference: Cisco: Internetworking Basics



Several UNIX TCP and UDP port numbers are allocated to well-known services such as finger, SMTP (mail) and HTTP (Web). If you connect to TCP port 13 of a UNIX machine, for example, that supports the daytime service and is not behind a firewall, then it will respond with the current time. The following table lists some of these services. Keep in mind that the complete table contains thousands of entries.

Selected UNIX TCP and UDP Services

Selected UNIX TCP and UDP Services
Port Protocol Service Description
7 TCP / UDP echo Echo Server
9 TCP / UDP discard Discard Server
11 TCP systat Active Users
13 TCP / UDP daytime Daytime Server
15 TCP netstat Netstat Server
17 TCP qotd Quote of the Day
18 TCP / UDP msp Message Send Protocol
19 TCP / UDP chargen TTYTST Source Character Generator
20 TCP ftp-data File Transfer (Data)
21 TCP ftp-data File Transfer (Control)
23 TCP telnet Telnet Server
25 TCP smtp Simple Mail Transfer Protocol
37 TCP / UDP time Time Server
43 TCP whois Who Is
53 TCP / UDP domain Domain Name Server
70 TCP gopher Gopher Server
79 TCP finger Finger Server
80 TCP http World Wide Web (HTTP)
443 TCP https World Wide Web (SSL - HTTP)
512 TCP exec BSD rexed
513 TCP login BSD rlogin
513 UDP who BSD rwhod
514 TCP shell BSD rshd
514 UDP syslog BSD syslogd
515 TCP printer BSD lpd
531 TCP conference Chat
6667 TCP irc Internet Relay Chat

About the Author

Jeffrey Hunter is an Oracle Certified Professional, Java Development Certified Professional, Author, and an Oracle ACE. Jeff currently works as a Senior Database Administrator for The DBA Zone, Inc. located in Pittsburgh, Pennsylvania. His work includes advanced performance tuning, Java and PL/SQL programming, developing high availability solutions, capacity planning, database security, and physical / logical database design in a UNIX / Linux server environment. Jeff's other interests include mathematical encryption theory, tutoring advanced mathematics, programming language processors (compilers and interpreters) in Java and C, LDAP, writing web-based database administration tools, and of course Linux. He has been a Sr. Database Administrator and Software Engineer for over 20 years and maintains his own website site at: Jeff graduated from Stanislaus State University in Turlock, California, with a Bachelor's degree in Computer Science and Mathematics.

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Last modified on
Wednesday, 28-Dec-2011 14:12:46 EST
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