These classnotes are depreciated. As of 2005, I no longer teach the classes. Notes will remain online for legacy purposes

UNIX01/Networking Overview In Linux

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As we have seen, Linux was a child of the modern internet. Thus, it should come as no surprise that Linux has excellent networking support and options.

Linux supports at the kernel level the following protocols:

Additionally, in userspace Linux can support many networking infrastructures such as SAMBA, LDAP, and SNMP (Simple Networking Management Protocol).

One of these things is not like the other

Berfore we proceed, it's important to touch upon how diverse the various UNIXes are with respect to networking. Depending upon which UNIX you are using, there are any number of ways in which networking subsystems are implimented. In fact, among the various Linux flavors, you will still find a pretty diverse bunch of networking setups.

But don't dismay: There is a method to this madness. We will cover the essentials and give you the working basics upon which you can easily build. The techniques and utilities discussed today will be applicable to most, if not all Linuxes. They will also have counterparts in other UNIXes, should the need arise. Additionally, in the courses ahead we will compare and contrast networking and services among several Linux and BSD flavors.

So while the items we discuss today will be fairly Linux-centric, they will supply a foundation for all other UNIXes.

File Abstraction Applied to Networking

Network devices and connectors are abstracted as files under UNIX. Before, we saw that the hard drives were patterned after one of /dev/hdX# or /dev/sdX# (for IDE and SCSI), with network devices it is very similar.

/dev/eth# is the device specification for the ethernet devices. The "#" symbol indicates the number the device is on the system. For example,

 /dev/eth0

is the first ethernet device, and

 /dev/eth1

is the second (so on and so forth)

/dev/ppp# is the device for the PPP devices. Often these are linked to a modem or some other device in /dev which provides the bridge for PPP. Something special to note about PPP is that, because of the way it is set up under Linux, many PPP controlling applications have some severe security problems. This is something to keep in mind when setting a PPP system up.

For more information on PPP under Linux, see http://tldp.org/HOWTO/PPP-HOWTO/index.html

The other networking protocols have similar naming conventions. We will not cover them in this class, but you can find out more about them at the networking section of The Linux Documentation Project:



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