Net-HOWTO

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Introduction

This is the first release of the GOLEM Network Howto, this document aims to be a sort of unofficial update of the Linux Networking Howto.

General Information about Networking

Sources of non-linux-specific network information

If you are looking for general TCP/IP networking information, here you can find some resources:

IPv4 Addresses

Ipv4-1.webp

Internet Protocol v4 Addresses are composed of 4 bytes (32 bit), each byte is converted to a decimal number (0-255) and bytes are separated by a . (dot), for this reason IPv4 addresses are limits to near 4 billions (232). Usually every network interface has its own IP address in a format like this: 192.168.0.5

Subnetting

Addresses in a network have some digits in common, that part is called the network portion of the address, the remaining numbers are called the host portion.

For example: 

           -----------------  ---------------
           Host Address       192.168.0.23
           Network Portion    192.168.0.
           Host portion                .23
           -----------------  ---------------
           Network Address    192.168.0.0
           Broadcast Address  192.168.0.255
           -----------------  ---------------

Subnetting is a way to subdivide an TCP/IP network. The Classless Inter-Domain Routing (CIDR) is the current method for defining subnet, the IP address is followed by a prefix number between 0 and 32 that shows how many bits represent the network. 

192.168.0.23/24 => network 192.168.0.0 - 192.168.0.255
192.168.0.23/16 => network 192.168.0.0 - 192.168.255.255

This method replace the obsolete classful network addressing architecture.

The maximum number of addresses of a network may be calculated as 232 − prefix number

CIDR Classful network mask Number of Hosts Typical use
/8 255.0.0.0 16777214 = 224 - 2 Largest IANA block allocation
/9 255.128.0.0 8388608 = 223
/10 255.192.0.0 4194304 = 222
/11 255.224.0.0 2097152 = 221
/12 255.240.0.0 1048576 = 220
/13 255.248.0.0 524288 = 219
/14 255.252.0.0 262144 = 218
/15 255.254.0.0 131072 = 217
/16 255.255.0.0 65536 = 216
/17 255.255.128.0 32768 = 215 ISP / large business
/18 255.255.192.0 16384 = 214 ISP / large business
/19 255.255.224.0 8192 = 213 ISP / large business
/20 255.255.240.0 4096 = 212 Small ISP / large business
/21 255.255.248.0 2048 = 211 Small ISP / large business
/22 255.255.252.0 1024 = 210
/23 255.255.254.0 512 = 29
/24 255.255.255.0 256 = 28 Large LAN
/25 255.255.255.128 128 = 27 Large LAN
/26 255.255.255.192 64 = 26 Small LAN
/27 255.255.255.224 32 = 25 Small LAN
/28 255.255.255.240 16 = 24 Small LAN
/29 255.255.255.248 8 = 2³ The smallest multi-host network
/30 255.255.255.252 4 = 2² Point-to-point links (glue network)
/31 255.255.255.254 2 = 21 Point-to-point network (RFC 3021)
/32 255.255.255.255 1 = 20 Single host

Traffic between subnets is guaranteed by routers.

Network Configuration

Driver

Modern Linux distributions already include driver for most of LAN and WiFi devices. Otherwise try to upgrade your OS or compile and install a newer kernel.

Network tools

iproute2: IP Routing Utilities

nftables: Linux kernel packet control tool (firewall)

iputils: arping, clockdiff, ping, tracepath

Legacy tools

net-tools: configuration tools for Linux networking (arp, ifconfig, ipmaddr, iptunnel, mii-tool, nameif, netstat, plipconfig, rarp, route, slattach)

iptables: Linux kernel packet control tool (firewall)

Network Application Programs

Most common network application programs are collected in the inetutils package: dnsdomainname, ftp, ftpd, hostname, ifconfig, ping, rcp, rlogin, rlogind, rsh, rshd, talk, talkd, telnet, telnetd, whois

Setup LAN Interfaces

# ip addr
# ip addr add 192.168.0.2/24 dev enp6s0
# ip route add default via 192.168.0.1


https://wiki.golem.linux.it/Appunti_Arch_Linux#Networking

Elencare gli indirizzi IP:

  1. ip addr

Mostra le informazioni di una specifica interfaccia di rete

  1. ip addr show eth0

Aggiungere un indirizzo all'interfaccia eth0:

  1. ip addr add 192.0.2.10/24 dev eth0

Cancellare un indirizzo associato all'interfaccia eth0:

  1. ip addr delete 192.0.2.10/24 dev eth0

Attivare l'interfaccia eth0:

  1. ip link set dev eth0 up

Disattivare l'interfaccia eth0:

  1. ip link set dev eth0 down

Svuotare la cache arp per tutte le interfacce:

  1. ip neigh flush all

Aggiungere una rotta che passa per gateway 192.0.2.1

  1. ip route add default via 192.0.2.1

Aggiungere una rotta che passa per gateway 192.168.2.1 per l'interfaccia 10.0.2.0

  1. ip route add 10.0.2.1/24 via 192.168.0.1 dev enp0s3

Aggiungere una rotta che passa per gateway 192.168.2.1 per l'interfaccia 10.0.2.0

  1. ip route del 10.0.2.0/24 via 192.168.0.1 dev enp0s3

Mostrare la tabella di routing

  1. ip route show

Bibliography

Linux Networking HOWTO

Estratto da "https://wiki.golem.linux.it/index.php?title=Net-HOWTO&oldid=9583"