IP Addressing and Subnetting

Anda sekalian pasti sudah tidak asing lagi dengan istilah IP, karena IP inilah yang memungkinkan kita untuk berkomunikasi dengan orang orang dari seluruh penjuru dunia yang terhubung ke internet. IP adalah singkatan dari Internet Protocol. Protokol disini saya analogi kan sebagai suatu bahasa penghantar yang digunakan oleh internet untuk dapat berkomunikasi satu dengan yang lainnya. Jika bahasa yang digunakan ini berbeda, maka komunikasi pun tidak dapat dilakukan. Layaknya seorang dari kampung A bertemu dengan seorang dari kampung B yang mempunyai bahasa berbeda, dapat dipastikan terjadi jaka sembung bawa golok, alias tidak nyambung..:)

Berawal dari konsep itulah, maka kita mengenal istilah TCP/IP yang digunakan untuk menyeragamkan semua protokol yang kita gunakan untuk dapat berkomunikasi dengen seluruh penjuru dunia yang terhubung dengan internet.

Mungkin anda bertanya-tanya, “jika saya terhubung di dalam suatu Local Area Network atau Wide Area Network, apakah saya memerlukan suatu alamat tertentu?”, jawabannya adalah “Ya, jelas sekali”. Contoh konkritnya, anda dapat mengetik winipcfg dari menu run*jika anda menggunakan o/s win95/98*, atau ipconfig dari dos prompt *jika anda menggunakan winNT* atau dapat juga mengetik ifconfig -a *jika anda mengunakan unix/linux*

Understanding ARP

If you’ve used TCP/IP or the Internet for any amount of time, you know that workstations on a TCP/IP network communicate with each other with a TCP/IP address. Over the physical network, however, workstations communicate with each other with their Media Access Control (MAC) address. Therefore, the key to communicating via TCP/IP is the mapping of a TCP/IP address to the physical address of a workstation. An Ethernet Address Resolution Protocol, RFC 826, details the conversion process from a TCP/IP address to a physical MAC address.

This process is relatively simple. In this example, the TCP/IP workstation 192.42.252.20 is planning to communicate to 192.42.252.50. To determine the physical address of the destination workstation, 192.42.252.20 sends a network broadcast to every station. This broadcast is seen by every workstation on the TCP/IP subnet.

The following portion of this initial frame shows the sender’s hardware and protocol (TCP/IP) address, and the target’s protocol address.

Enable MAC Address Filtering on Wireless Access Points and Routers

Improve home network security

Most Wi-Fi access points and routers ship with a feature called hardware or MAC address filtering. This feature is normally turned “off” by the manufacturer, because it requires a bit of effort to set up properly. However, to improve the security of your Wi-Fi LAN (WLAN), strongly consider enabling and using MAC address filtering.Without MAC address filtering, any wireless client can join (authenticate with) a Wi-Fi network if they know the network name (also called the SSID) and perhaps a few other security parameters like encryption keys. When MAC address filtering is enabled, however, the access point or router performs an additional check on a different parameter. Obviously the more checks that are made, the greater the likelihood of preventing network break-ins.

To set up MAC address filtering, you as a WLAN administrator must configure a list of clients that will be allowed to join the network.

First, obtain the MAC addresses of each client from its operating system or configuration utility. Then, they enter those addresses into a configuratin screen of the wireless access point or router. Finally, switch on the filtering option.

Once enabled, whenever the wireless access point or router receives a request to join with the WLAN, it compares the MAC address of that client against the administrator’s list. Clients on the list authenticate as normal; clients not on the list are denied any access to the WLAN.

MAC addresses on wireless clients can’t be changed as they are burned into the hardware. However, some wireless clients allow their MAC address to be “impersonated” or “spoofed” in software. It’s certainly possible for a determined hacker to break into your WLAN by configuring their client to spoof one of your MAC addresses. Although MAC address filtering isn’t bulletproof, still it remains a helpful additional layer of defense that improves overall Wi-Fi network security.

Do not confuse MAC address filtering with content filtering. Content filtering on a wireless access point or router allows administrators to maintain a list of Web site URLs or addresses that should not be accessed from the home WLAN.

From Bradley Mitchell,
Your Guide to Wireless / Networking.

Meta Tags in Search Engine Optimization

META tags have, for a number of years, formed the cornerstone of many search engine optimization efforts, along with other HTML tags, the right keywords, good site design and proper use of links.

Meta tags are found within the HEAD tags and provide a variety of information about a web page, which, although hidden from browsers (and site visitors), can be used by search engines to rank and classify web pages.

The incorporation of meta tag reading in many search engines’ indexing formulas have thus allowed site owners to have some degree of control over the way their web pages are described, just be optimizing their use of this HTML code.

And in case you too are considering the use of this tag in your search engine optimisation strategy, here are some types that may be of interest:

Most used in SEO: <meta name=”Keywords” content=”first, second, third*” />

Search Engine Optimization – Introduction

As more and more sites populate the World Wide Web, getting yours noticed (and read for that matter) becomes more and more of a challenge. It’s not so bad (though this is really a matter of opinion) if you don’t make your living out of it (i.e. it’s just a hobby site), but what if you do?

The field of ecommerce has become so competitive that when it comes to getting a search engine results page (SERP) listing, most companies only dream of landing in the top 5. After all, with the millions or billions of sites out there, even getting a listing in the top 10 pages would be an accomplishment! And if you land beyond that? Well.let me put it this way, would YOU even bother clicking beyond the top ten pages?

High Performance/Traffic PHP WebServer – PHP Caching (eaccelerator)

eAccelerator is a PHP caching system, which caches frequently used portions of PHP files to RAM to increase performance. This is especially great on high traffic websites such as forums. Performance gains of up to 1000% have been seen with eAccelerator. The following tutorial shows how to install eAccelerator from source on Linux.

Download the source:

cd /usr/src/
wget http://internap.dl.sourceforge.net/sourceforge/eaccelerator/eaccelerator-0.9.3.tar.gz
tar zxvf eaccelerator-0.9.3.tar.gz
cd eaccelerator-0.9.3

Guide to Setting Up Your Own Website

You’ve finally decided to put up your own site on the Internet, but have absolutely no idea how to go about it. Scared? Intimidated? Don’t be. After all, you really don’t need to be a rocket scientist to do so.

Creating a website involves four simple steps. We can call this the 4Ds: Domain, Design, Decide and Deploy.

Step 1. Get a Domain name.

This is a crucial step. Just as you can’t go through life without a name, you also can’t put up a website without a domain name. But what exactly is a domain name?

Hacking Attacks – How and Why

In this age of prolific Internet use, a major concern that has emerged among webmasters and web hosts alike is the threat of hacking. Originally referring to the process of learning programming languages and computer systems, the term ‘hacking’ has now evolved to mean the practice of bypassing a computer system/network’s security (used interchangeably with the term ‘cracking,’ depending on the motivation).

At any rate, hacking attacks have now become threats that system administrators and webmasters need to guard against.

There are five forms of attacks commonly used against computers and networks, according to Aaron Turpen, in his article ‘Hacker Prevention Techniques.’

1. Distributed Denial of Service (DDoS) attacks

Hacking Attacks – Prevention

The first three steps are suggested by security consultant Jay Beale in his interview with Grant Gross, when asked how administrators can protect themselves from system attacks.

1. Harden your systems (also called “lock-down” or “security tightening”) by

* Configuring necessary software for better security
* Deactivating unnecessary software – disable any daemons that aren’t needed or seldom used, as they’re the most vulnerable to attacks
* Configuring the base operating system for increased security

2. Patch all your systems – Intruders can gain root access through the vulnerabilities (or “holes”)

Belajar sendiri pasang kabel UTP untuk jaringan

Tutorial singkat ini cocok sekali buat Anda yang sedang membuat jaringan komputer ‘MURAH’ khususnya yang terdiri lebih dari dua client yang pake hub (jauh lebih murah daripada router ). To the point! Apa sih kabel UTP itu? Kabel UTP itu adalah kabel khusus buat transmisi data. UTP, singkatan dari “Unshielded Twisted Pair”. Disebut unshielded karena kurang tahan terhadap interferensi elektromagnetik. Dan disebut twisted pair karena di dalamnya terdapat pasangan kabel yang disusun spiral alias saling berlilitan. Ada 5 kategori kabel UTP. Dari kategori 1 sampai kategori 5. Untuk jaringan komputer yang terkenal adalah kategori 3 dan kategori 5.