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109: Networking Fundamentals

Tom Ormiston edited this page Aug 30, 2017 · 23 revisions

109.1 Fundamentals of internet protocols

Description: Candidates should demonstrate a proper understanding of TCP/IP network fundamentals.

Key Knowledge Areas:

Demonstrate an understanding of network masks and CIDR notation Knowledge of the differences between private and public “dotted quad” IP addresses Knowledge about common TCP and UDP ports and services (20, 21, 22, 23, 25, 53, 80, 110, 123, 139, 143, 161, 162, 389, 443, 465, 514, 636, 993, 995) Knowledge about the differences and major features of UDP, TCP and ICMP Knowledge of the major differences between IPv4 and IPv6 Knowledge of the basic features of IPv6

Terms and Utilities:

/etc/services
IPv4, IPv6
Subnetting
TCP, UDP, ICMP

Opensource.com: An introduction to Linux network routing

Steven Gordon: Links vs networks; layering, OSI 7 layer model, TCP/IP 5 layer model

Steven Gordon: Internetworking, routers and hosts, the Internet Protocol

Steven Gordon: IP Addressing

Steven Gordon: Special IP addresses


Brian Will: An intro to IPv4, TCP, UDP, and HTTP


Brian Will: the internet


109.2 Basic network configuration

Description: Candidates should be able to view, change and verify configuration settings on client hosts.

Key Knowledge Areas:

Manually and automatically configure network interfaces Basic TCP/IP host configuration Setting a default route

Terms and Utilities:

/etc/hostname
/etc/hosts
/etc/nsswitch.conf
ifconfig
ifup
ifdown
ip
route
ping

UrbanPenguin: Basic Network Configuration

Haktip: Networking Commands You Should Know Pt 1- ping, traceroute, and netstat

Haktip: Networking Commands You Should Know Pt2

Haktip: ifconfig vs ip

109.3 Basic network troubleshooting

Description: Candidates should be able to troubleshoot networking issues on client hosts.

Key Knowledge Areas:

Manually and automatically configure network interfaces and routing tables to include adding, starting, stopping, restarting, deleting or reconfiguring network interfaces
Change, view, or configure the routing table and correct an improperly set default route manually
Debug problems associated with the network configuration

Terms and Utilities:

ifconfig
ip
ifup
ifdown
route
host
hostname
dig
netstat
ping
ping6
traceroute
traceroute6
tracepath
tracepath6
netcat

UrbanPenguin: Network troubleshooting

tutorialLinux: What's happening on this machine?

Linux Command Review: ifconfig, ethtool, arp, netstat

Steven Gordon: Capturing Ping in a Virtual Linux Network

Steven Gordon: Netcat and TCP in a Virtual Linux Network

Steven Gordon: ifconfig, ethtool, netstat

Steven Gordon: Address Resolution Protocol -arp

Steven Gordon: netstat, /etc/services, /etc/protocols

Steven Gordon: netcat, nc

Steven Gordon: Routing table, netstat -r, route

Packet Capture: tcpdump

Packet Capture: Wireshark (2 of 3)

Packet Capture: Packet and Message Sequence

109.4 Configure client side DNS

Description: Candidates should be able to configure DNS on a client host.

Key Knowledge Areas:

Query remote DNS servers Configure local name resolution and use remote DNS servers Modify the order in which name resolution is done

Terms and Utilities:

/etc/hosts
/etc/resolv.conf
/etc/nsswitch.conf
host
dig
getent

UrbanPenguin: Client Side DNS

Quidsip: How to setup DDClient - Dynamic DNS IP Updater for Ubuntu


lsof Command

IBM: Finding open files with lsof

tutorialLinux: 8 Basic lsof Commands Every Sysadmin Needs to Know

10 lsof Command Examples in Linux

crybit: 10 lsof command usages with example


Refreshing network connections for intermittent wifi

Joe Collins: Refresh Network Connections with a Command on Ubuntu

Refresh Network Connections Script and create a script to run this command

For Upstart: sudo service network-manager restart

For systemd: sudo systemctl restart network-manager


Wireshark

A popular network analysis and packet capture tool

HakTip: Wireshark - Packet Capturing and Analysis a 30+ series

Wireshark 101: How to Wireshark, Haktip 115


Networking circa 2006 ish

Networking covers a wide range of topics, though its slightly dated the basic stuff is still worth knowing.

Exercises in networking may be helpful