From LQWiki

This article explains Networking by linking to detailed topics.

Contents 1 Introduction 1.1 Networking concepts crash course 2 How to... 3 Advanced Networking 4 Network services 5 Configuration 6 See also

Introduction

Read this if you do not have a concrete question.

• Network - Tools you can use etc.
• Network Addressing
• Network Troubleshooting - Solving Network Problems

Networking concepts crash course

Layer 3 switch = router

A VLAN is a software way of setting up a seperate network. It's the same as having a totally seperate switch for each new Local Area Network (aka LAN) or what we call a Virtual LAN...voila! VLAN. Try to think of it as each VLAN being a seperate switch, except the part where you have to actually seperate the switches and move cables to change the network that a host is in. Rather than moving network cables in the wiring closet in the back room, you can change VLAN settings remotly from your laptop in Tahiti.

A switch, or layer 2 (OSI layer 2) device can isolate VLANs, or networks, but can't get them to talk to each other. The exception is plugging VLANs into each other, which defeats the purpose of having two VLANs. You set up a VLAN to isolate a network segment at OSI layer 2.

A router, or a 'layer 3 switch', connects IP subnets (OK it connects other network protocols, but this is 2005 so it's either TCP/IP or 'some other protocol'.) You seperate a network at the IP level by changing IP addresses and you can divide the pre-defined class A, B and C networks into smaller ones by also changing the subnet mask.

An IP subnet is usually put on a network with no other IP subnets on it. This can be done by putting all the hosts on one switch and plugging a router into one of that switch's ports. It can also be done by configuring a VLAN and setting your layer 3 switch to route packets out of that VLAN. When you have a seperate IP network segment, it's called a broadcast domain. Each broadcast domain sees all the layer 3 and layer 2 broadcasts from any host in the same broadcast domain.

At OSI layer 1, the physical layer, all the voltage signals sent over the wire are defined. A hub doesn't have to know about MAC addresses (layer 2) or IP addresses (layer 3) it just has to re-transmit the right voltage signal to other ports. This is also called a collision domain because one host's output goes to all other host's input so the hosts have to share the bandwidth and their data can collide and then need to be sent again.

How to...

Here you learn how to:

• Set up your modem
• Set up broadband
  • Set up broadband using PPoE
  • Set up broadband using PPTP client
  • Set up NTL
• Set up wireless networking
• Share files with Windows computers
• Network Setup - Setting up Router/Default Gateway
• Kill Sockets

Advanced Networking

• Bridging made easy - Explains how to configure bridging to run within existing (RedHat-esque) scripts.
• LVS with HA for Win2k Terminal Servers - Explicit setup instructions for High Availability Load Balancing.
• LVS with High Availability and load balancing for any server
• Networking security
• Firewall
• Network Setup - Setting up Router/Default Gateway with Red Hat 9.0 Tutorial

Network services

• Typical port numbers for services: List of port numbers
• tcp-wrappers - A package to monitor and forward incoming requests for various services.
• Samba - Information on sharing files with Windows machines.
• Netatalk - Information on sharing files and printers between Linux and Macintosh machines.
• List of Web servers - Looking to set up a webserver? Take a look here.
• inetd and xinetd configuration - internet services daemons.
• SSH
• Remote Desktop Connection - Connect to other computers with VNC, XDCMP, SSH or telnet.
• Diskless Workstation - Configure tftp, dhcp, and nfs for diskless netboot
• Open sharedroot diskless Workstation/Server - Configure tftp, dhcp, and nfs for sharedroot diskless netboot
• Mail services
  • SMTP services
  • POP3 services
  • IMAP services
• The Domain Name System (DNS)
• Network Information Service (NIS)

Configuration

• Add/Edit IP Addresses in Debian linux (www1.netmonitoring.org)
• Add Static Routes in Debian Linux (www.itsyourip.com)
• Add/Edit IP Addresses in Redhat Enterprise linux (www1.netmonitoring.org)

• Add Static Routes in Redhat Enterprise Linux (www.itsyourip.com)
• Rename Network Interface Using Udev (www.debianadmin.com)
• Red Hat Configuration (www.redhat.com)
• Debian Networking Tutorials (www.debianhelp.co.uk)
• Monitoring Network using Nagios - Tutorials (www.debianhelp.co.uk)
• Debian Configuration (www.debian.org)
• Slackware Configuration (www.slackware.com)
• Mandriva Configuration (club.mandriva.com)

See also

• A basic firewall configuration suitable for a workstation
• A basic firewall configuration suitable for a gateway/nat
• Manual configuration of an iptables firewall