Every network that has an internet connection is at risk of being compromised. Whilst there are several steps that you can take to secure your LAN, the only real solution is to close your LAN to incoming traffic, and restrict outgoing traffic.
However some services such as web or FTP servers require incoming connections. If you require these services you will need to consider whether it is essential that these servers are part of the LAN, or whether they can be placed in a physically separate network known as a DMZ (or demilitarised zone if you prefer its proper name). Ideally all servers in the DMZ will be stand alone servers, with unique logons and passwords for each server. If you require a backup server for machines within the DMZ then you should acquire a dedicated machine and keep the backup solution separate from the LAN backup solution.
The DMZ will come directly off the firewall, which means that there are two routes in and out of the DMZ, traffic to and from the internet, and traffic to and from the LAN. Traffic between the DMZ and your LAN would be treated totally separately to traffic between your DMZ and the Internet. Incoming traffic from the internet would be routed directly to your DMZ.
Therefore if any hacker where to compromise a machine within the DMZ, then the only network they would have access to would be the DMZ. The hacker would have little or no access to the LAN. It would also be the case that any virus infection or other security compromise within the LAN would not be able to migrate to the DMZ.
In order for the DMZ to be effective, you will have to keep the traffic between the LAN and the DMZ to a minimum. In the majority of cases, the only traffic required between the LAN and the DMZ is FTP. If you do not have physical access to the servers, you will also need some sort of remote management protocol such as terminal services or VNC.
Database servers
If your web servers require access to a database server, then you will need to consider where to place your database. The most secure place to locate a database server is to create yet another physically separate network called the secure zone, and to place the database server there.
The Secure zone is also a physically separate network connected directly to the firewall. The Secure zone is by definition the most secure place on the network. The only access to or from the secure zone would be the database connection from the DMZ (and LAN if required).
Exceptions to the rule
The dilemma faced by network engineers is where to put the email server. It requires SMTP connection to the internet, yet it also requires domain access from the LAN. If you where to place this server in the DMZ, the domain traffic would compromise the integrity of the DMZ, making it simply an extension of the LAN. Therefore in our opinion, the only place you can put an email server is on the LAN and allow SMTP traffic into this server. However we would recommend against allowing any form of HTTP access into this server. If your users require access to their mail from outside the network, it would be far more secure to look at some form of VPN solution. (with the firewall handling the VPN connections. LAN based VPN servers allow the VPN traffic onto the network before it is authenticated, which is never a good thing.)
How Web Servers Work
Everyone loves it when lots of traffic comes through their website. In fact, many do whatever they can to achieve that traffic in hopes that someone will find what is on their site interesting and will make a purchase from the site. That's the idea, right? Of course it is, but it is a fact that traffic of all types may not be very beneficial if it isn't targeted traffic. However, there are ways in which traffic is brought to sites and two of these are DOS Attack and Digg Traffic. There are actual differences between the two as far as how they bring traffic to websites. Let's just say that one is more vicious than the other.
DOS Attack
Dos Attack makes the web server beg for mercy because it is flooded with traffic that can actually be considered useless. There are different kinds of DOS Attacks such as Teardrop and Ping of Death. What these do is exploit the limitations of the TCP/IP protocols. However, there are software fixes that administrators administer to their systems to reduce the damage that is done by DOS Attacks. But just like computer viruses, there are always new attacks being created by hackers. What these attacks do is keep the website from functioning properly and usually target large sites such as those of banks and credit card sites. The Teardrop attack sends IP fragments with huge payloads that are overlapping to the machine that they are targeting. Many operating systems are vulnerable to this type of attack and can crash the entire system.
There is also an attack called the Smurf Attack in which it floods the internet by sending packets of information to be sent to the computer hosts on a certain network. This is one of those methods in which it appears a website is receiving a lot of traffic, but none of the traffic is legitimate. SYN Flood is another that floods the servers to appear as legitimate traffic.
Digg Traffic
Digg is actually a legitimate way to generate traffic to websites. It is community-based and uses articles to gain traffic. It combines blogging, social bookmarking, and syndication with editorial control by the users. Websites and news stories are submitted by the users and a user-based ranking system is used to promote the website. It can happen that the web server is not prepared to manage that high incoming traffic and ultimately crashes the site for a short time. However, Digg has met some controversy because it is said the users have entirely too much control over the content. There are even users who have been accused of operating what is called a "Bury Brigade" in which users mark articles as SPAM, which can bury these legitimate stories under the ones that users want to promote, whether they are legitimate or not.
The differences
The differences are rather clean in that DOS attacks are a way in which hackers maliciously flood systems with fake traffic and can actually disable use of a website. It is not a legitimate way to gain traffic, whereas Digg is a legitimate method. However, even Digg has met its controversy in which traffic can be directed away from legitimate articles due to "Bury Brigades," which can hinder one's ability to promote through Digg's system. Yet as with any system on the internet, there are always ways to compromise its original intent and Digg is not an exception. DOS Attacks, on the other hand, still do what they are intended to do and that is to maliciously attack the web.
Both Chris Weight & Amy Nutt are contributors for EditorialToday. The above articles have been edited for relevancy and timeliness. All write-ups, reviews, tips and guides published by EditorialToday.com and its partners or affiliates are for informational purposes only. They should not be used for any legal or any other type of advice. We do not endorse any author, contributor, writer or article posted by our team.
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