109 Networking Fundamentals KT Flashcards
109.1 Fundamentals of internet protocols
The following is a partial list of the used files, terms and utilities:
/etc/services
IPv4, IPv6
Subnetting
TCP, UDP, ICMP
/etc/services
/etc/services file contains a list of network services and ports mapped to them.
IPv4, IPv6
IPv4: Internet Protocol version 4 is a 32 bit addressing scheme that is used to identify machines on a network.
IPv6: Internet Protocol version 6 is a 128 bit addressing scheme that is used to identify machines on a network.
Subnetting
A subnetwork or subnet is a logical subdivision of an IP network.
TCP, UDP, ICMP
TCP: Transmission Control Protocol is a connection oriented internet protocol suite.
UDP: User Datagram Protocol is a connectionless internet protocol suite.
ICMP: Internet Control Messaging Protocol is used by network devices to send error messages, as well as operational messages indicating success or failure.
109.2 Persistent network configuration
The following is a partial list of the used files, terms and utilities:
/etc/hostname /etc/hosts /etc/nsswitch.conf /etc/resolv.conf nmcli hostnamectl ifup ifdown
/etc/hostname
/etc/hostname contains name of the machine, as known to applications that run locally.
/etc/hosts
The /etc/hosts file hosts is an operating system file that maps hostnames to IP addresses. It is a plain text file.
/etc/nsswitch.conf
The Name Service Switch (NSS) configuration file, /etc/nsswitch.conf, is used by the GNU C Library and certain other applications to determine the sources from which to obtain name-service information in a range of categories, and in what order.
/etc/resolv.conf
The /etc/resolv.conf configuration file contains information that allows a computer to convert alpha-numeric domain names into the numeric IP addresses.
nmcli
Command: nmcli is a command-line tool for controlling NetworkManager and getting its status.
nmcli [ OPTIONS ] OBJECT { COMMAND | help }
OBJECT := { nm | con | dev }
OPTIONS := { -t[erse] -p[retty] -m[mode] tabular | multiline -f[ields] | all | common -e[scape] yes | no -v[ersion] -h[elp] }
hostnamectl
Command: hostnamectl may be used to query and change the system hostname and related settings.
hostnamectl [OPTIONS…] {COMMAND}
ifup
Command: The ifup and ifdown commands may be used to configure (or, respectively, deconfigure) network interfaces based on interface definitions in the file /etc/network/interfaces.
ifup [-nv] [–no-act] [–verbose] [-i FILE|–interfaces=FILE] [–state-dir=DIR] [–allow CLASS] -a | IFACE…
ifdown [-nv] [–no-act] [–verbose] [-i FILE|–interfaces=FILE] [–state-dir=DIR] [–allow CLASS] -a | IFACE…
ifdown
Command: The ifup and ifdown commands may be used to configure (or, respectively, deconfigure) network interfaces based on interface definitions in the file /etc/network/interfaces.
ifup [-nv] [–no-act] [–verbose] [-i FILE|–interfaces=FILE] [–state-dir=DIR] [–allow CLASS] -a | IFACE…
ifdown [-nv] [–no-act] [–verbose] [-i FILE|–interfaces=FILE] [–state-dir=DIR] [–allow CLASS] -a | IFACE…
109.3 Basic network troubleshooting
The following is a partial list of the used files, terms and utilities:
ip hostname ss ping ping6 traceroute traceroute6 tracepath tracepath6 netcat ifconfig netstat route