1. Context 11 Model of network layers 12 Basic Internet Protocols 1.112.1 2 4 5 5 5 5 6 1.112.1 Fundamentals of TCP/IP Weight 4 Linux Professional Institute Certification — 102 13 Ports and Port Numbers 13.1 /etc/services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2 Main port numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 License of this document 1 Geoffrey Robertson ge@ffrey.com Nick Urbanik nicku@nicku.org This document Licensed under GPL—see section 14 Context Topic 112 Networking Fundamentals [14] 1.112.1 Fundamentals of TCP/IP [4] 1.112.3 TCP/IP configuration and troubleshooting [7] 2005 July Outline 1.112.4 Configure Linux as a PPP client [3] 2 Objective Contents 1 2 3 4 5 6 7 8 9 Context Objective Context Resources IP Addressing Classful Addressing (Obsolete) Loopback address Private addresses Subnetting 1 1 2 2 3 3 3 4 4 Description of Objective Candidates should demonstrate a proper understanding of network fundamentals. This objective includes the understanding of IP-addresses, network masks and what they mean (i.e. determine a network and broadcast address for a host based on its subnet mask in “dotted quad” or abbreviated notation or determine the network address, broadcast address and netmask when given an IP-address and number of bits). It also covers the understanding of the network classes and classless subnets (CIDR) and the reserved addresses for private network use. It includes the understanding of the function and application of a default route. It also includes the understanding of basic internet protocols (IP, ICMP, TCP, UDP) and the more common TCP and UDP ports (20, 21, 23, 25, 53, 80, 110, 119, 139, 143, 161). Key files, terms, and utilities include: /etc/services — file mapping port numbers to names ftp — FTP client program telnet — telnet client program host — program to test DNS servers 10 Adding a Default Route 4 ping — program to test connectivity to other machines via ICMP 3. Context dig — program to test DNS servers 1.112.1 3 6. Classful Addressing (Obsolete) 1.112.1 4 6 Classful Addressing (Obsolete) traceroute — program to test the path to a remote machine, showing routers along the way whois — queries information about the owner of a domain IP Address Classes (Classic) Class A — 255.0.0.0 00000000.00000000.00000000.00000000 - 0.0.0.0 01111111.11111111.11111111.11111111 - 127.255.255.255 Class B — 255.255.0.0 10000000.00000000.00000000.00000000 - 128.0.0.0 10111111.11111111.11111111.11111111 - 191.255.255.255 Class C — 255.255.255.0 11000000.00000000.00000000.00000000 - 192.0.0.0 11011111.11111111.11111111.11111111 - 223.255.255.255 3 Context (2.2) Networking Fundamentals [14] 1.112.1 Fundamentals of TCP/IP [4] 1.112.3 TCP/IP configuration and troubleshooting [7] 1.112.4 Configure Linux as a PPP client [3] 4 Resources Fundamentals of TCP/IP [4] 7 References [1] W. Richard Stevens. TCP/IP Illustrated, Volume 1: The Protocols Addison Wesley [2] Olaf Kirch and Terry Dawson. Linux Network Administrator’s Guide O’Reilly 2000. http://tldp.org/LDP/nag2/ [3] Angie Nash and Jason Nash. LPIC 1 Certification Bible Hungry Minds Loopback address IP Address - Loopback Reserved Space 127.0.0.0 — 127.255.255.255 127.0.0.1 localhost 8 Private addresses 5 IP Addressing IP addressing This objective includes the understanding of: • IP-addresses, network masks and what they mean, i.e., – determine a network and broadcast address for a host based on its subnet mask in “dotted quad” or abbreviated notation or – determine the network address, broadcast address and netmask when given an IP-address and number of bits. IP Address - Private Networks There are IP ranges set aside for privite address spaces. These should not be made visible on the internet. Class A 10.0.0.0 -- 10.255.255.255 Class B 172.16.0.0 -- 172.32.255.255 Class C 192.168.0.0 -- 192.168.255.255 9. Subnetting 1.112.1 5 13.2 Main port numbers 1.112.1 6 9 Subnetting IP Address — Subneting Network: 192.168.192.0 Subnet: 255.255.255.224 10 Adding a Default Route IP Address - Default Route $ sudo route add default gw 192.168.1.1 ← $ less /etc/services ftp 21/tcp ftp 21/udp fsp fspd ssh 22/tcp # SSH Remote Login Protocol ssh 22/udp # SSH Remote Login Protocol telnet 23/tcp telnet 23/udp # 24 - private mail system smtp 25/tcp mail smtp 25/udp mail time 37/tcp timserver 11 Model of network layers DoD Layer Model Application ftp, telnet, mail, http protocols Transport TCP , UDP protocols Network IP, ICMP, IGMP protocols Link Ethernet, Token Ring, FDDI 13.2 Main port numbers Ports and Port Numbers FTP 20, 21 Telnet 23 SSH 22 smtp 25 DNS 53 http 80 pop3 110 12 Basic Internet Protocols Basic Internet Protocols IP ICMP TCP UDP nntp 119 netbios 137, 138, 139 imap2 143 snmp 161 Port Number vRanges 13 Ports and Port Numbers 13.1 /etc/services Ports and Port Numbers 5 1–255 Original reserved ports (till 1992) (256-1023 UNIX) 1–1023 Well Known or Famous Port Numbers - Reserved 1024–65535 Unprivileged 14. License of this document 1.112.1 7 14 License of this document License Of This Document Copyright c 2005, 2003 Geoffrey Robertson and Nick Urbanik . Permission is granted to make and distribute verbatim copies or modified versions of this document provided that this copyright notice and this permission notice are preserved on all copies under the terms of the GNU General Public License as published by the Free Software Foundation—either version 2 of the License or (at your option) any later version.