lk/networking/protocols.md

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2022-01-16 18:20:39 +00:00
---
title: "protocols"
tags: [ "Documentation", "networking" ]
---
2020-01-02 00:04:35 +00:00
# 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
## IPv4
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
# Service Ports
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
# ip
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