Network Security Assessment, 2nd Edition

Appendix A. TCP, UDP Ports, and ICMP Message Types

I list useful TCP, UDP ports, and ICMP message types in this appendix. A comprehensive list of registered TCP and UDP services may be found at http://www.iana.org/assignments/port-numbers. The nmap-services list of ports provided with Nmap is also a good reference, particularly for backdoors and other unregistered services.

TCP Ports

TCP ports of interest from a remote security assessment perspective are listed in Table A-1. I have included references to chapters within this book, along with other details that I deem appropriate, including MITRE CVE references to known issues.

Table A-1. TCP ports

Port	Name	Notes
1	tcpmux	TCP port multiplexer, indicates the host is running IRIX
11	systat	System status service
15	netstat	Network status service
21	ftp	File Transfer Protocol (FTP) service; see Chapter 8
22	ssh	Secure Shell (SSH); see Chapter 8
23	telnet	Telnet service; see Chapter 8
25	smtp	Simple Mail Transfer Protocol (SMTP); see Chapter 11
42	wins	Microsoft WINS name service; see Chapter 5
43	whois	WHOIS service; see Chapter 3
53	domain	Domain Name Service (DNS); see Chapter 5
79	finger	Finger service, used to report active users; see Chapter 5
80	http	Hypertext Transfer Protocol (HTTP); see Chapter 6
88	kerberos	Kerberos distributed authentication mechanism
98	linuxconf	Linuxconf service, remotely exploitable under older Linux distributions; see CVE-2000-0017
109	pop2	Post Office Protocol 2 (POP2), rarely used
110	pop3	Post Office Protocol 3 (POP3); ...