Protocols

TCP	UDP	ICMP
Transmission Control Protocol	User Datagram Protocol	Internet Control Message Protocol
Reliable and slow.	Fast but unreliable, such as VOIP. Provides checksums.	Dirty checks such as pings.

Networking Addressing

Three address ranges pertain only to private networks, so no computer looks beyond the local router to resolve them:

10.0.0.0 to 10.255.255.255

172.16.0.0 to 172.31.255.255

192.168.0.0 to 192.168.255.255

In theory, networks should fall within one of 3 ranges, depending upon their first octet:

Class A 1-127

Class B 128 to 191

Class C 192 to 223

There are three types of port ranges:

1 to 1023: Well-known and established ports.

1024 to 49151 ICANN registered ports, used by various products, with limited oversight.

49152 to 65535 Dynamic ports for ad hoc use.

View a more complete list of ports with:

less /etc/services

Show all addresses with:

ip a{dd{ress}} s{how}

If a link's not present, load it with:

sudo ip link set dev wlp3s0 up

Add an interface to a device as so:

sudo ip a add 192.168.0.15/255.255.255.0 dev eth1

See network interfaces available on Fedora with:

less /etc/sysconfig/network-scripts/ifcfg-enp2s0f0

or on Debian with:

less /etc/network/interfaces

Mostly, interfaces will receive automatic addresses from a DHCP server. If this hasn't happened for you, you can request a dhcp address with:

sudo dhclient eth1

View your current route to the internet with:

route

... although on void this is:

routel

If you don't have a route to the internet, you can manually specify the default gateway with:

sudo route add default gw 192.168.0.1

... or ...

sudo ip route add default via 192.168.0.1