iptables firewall for linux

firewall for linux, firewall is script or packet software for protect your network or server from attack from other network. iptables is powerfull packet software on linux for firewall. iptables preserves the basic ideas introduced with ipfwadm: lists of rules each of which specified what to match within a packet, and what to do with such a packet.

iptables extended this further into tables: one table was consulted when deciding whether to NAT a packet, and another consulted when deciding how to filter a packet. In addition, the three filtering points in a packet's journey were altered such that any packet only passes through one filtering point. basic filtering with iptables is with chain below:

“PREROUTING”: all data Packets will in to this chain before a routing decision is made.

“INPUT”: all data Packet will deliver locally delivered. It does't have anything to do with processes having a socket open. Local delivery is controlled by the “local-delivery” routing table: `ip route show table local`.)

“FORWARD”: All data packets that have been routed and not for local delivery will traverse this chain.

“OUTPUT”: all data Packets sent from the system itself and will be visiting this chain rule.

“POSTROUTING”: Routing decision has been made and all Packets enter this chain just before handing them off to the hardware.

Each rule in a chain contains the specification of which packets it matches. It may also contain a target (used for extensions) or verdict (one of the built-in decisions). As a packet traverses a chain, each rule in turn is examined. If a rule does not match the packet, the packet is passed to the next rule

basic linux security tip

linux is open source operating system with unix like kernel. founder linux, linus trovald say if linux is for open source development. in linux system we know about firewall can use to protect our system from attack outside. phising, malware, spam or denial of service. below tips for basic security for protect your system :

1. open just for use port for your system you can use iptables for open and close port on your system.
2. change your password for one week
   
3. change default port for ssh with 2222 or other and filter your outside network for access it
   
4. use secure ftp for file transfer
   
5. limit udp trafic from outside network to protect your network or system from denial of service.
6. change permision file with read only
   
7. and last always update your repisitory
   

usually linux use iptables for default firewall. but we can use ip chains if that more familiar.

Overview of Mobile Wireless Computing

The ability to travel for work is essential for any professional in those days. That is why the laptops are essential. With the Internet on a laptop is also important when you have to keep in touch with the work. Get wireless for your laptop is essential if you are a professional courtesy. It 'important that if you like, a mobile wireless capability to ensure the best possible deal to go out and maximize the potential of the team. The mobility of laptop users are not restricted by wires to travel as a WLAN is very convenient. Wireless internet is becoming better and faster, and almost a necessity for all laptops.

After the WLAN on the laptop allows you to do business in a reasonable and easy to perform. With a free Wi-Fi on your laptop, for example, is making it much easier. It is becoming increasingly popular. The ability to connect to the Internet while driving, the user's e-mail constantly, so that the contacts, access to information as the data could have, and increase productivity. To connect to the Internet with a laptop can connect to a wireless router. It 'requires that the laptop must have the correct network card with a WiFi connection. There are many public spaces that allow the wireless connection in all the western cities. The link quality varies from place to place, because it depends on several factors. In general, the quality of the connection depends on the quality of the radio signal received your laptop. Closer or farther from the source of the signal ultimately determines the resistance and therefore the quality and, possibly, the speed of your connection. WiFi connectivity constant at all hours of the day and every day of the week.

Currently manufactures notebook and invest time and money to improve their products and network speed. In recent years, the wireless network has a long way in terms of quality and strength. If the laptops were a few years ago introduced the concept of mobile network already in place. However, it was immature and had many gaps. Over the years, expanding wireless capabilities, which can be overcome with increased connectivity, improved networks and increased productivity. As a result, and the constant advances in technology, the laptop user these days you can use the computer and not worry about looking for a modem or router and all cables. Just click on the computer and start surfing related. areas or because of the growing popularity of the public have access to respond to this new trend. Public libraries, airports, or even some companies offer wireless Internet access for their customers. In many cities of the interior of North America, the existence of many wireless networks operating in the same place, making it virtually impossible for an Internet connection for online registration. The only downside is that wireless technology with health risks, which we know has not yet been assigned. In general, however, wireless computer the way for the student business, or other users of computer fans.

ecuring Your Windows XP Home Computer

Most people are aware that there is an ongoing program with the issue of security of the operating system Microsoft Windows and others. But what many people do not know how easy it is to significantly improve the security of your computer and the likelihood of a victim must be confined to increasingly complex threats, increasingly, is lurking on the Internet. These steps must be less than a couple of hours and not be swept away his wallet.

1) Update for Windows - the first crucial step to take to ensure that all applications installed on the latest Microsoft product updates. These updates and patches for security flaws and other problems. Microsoft usually gives updates on a monthly cycle. Visit the Microsoft Web site or switch to automatic updates of the Control Panel. Even if your equipment "new" used, there is still an important first step. If you buy a used computer with Windows XP, make sure you have Service Pack 2 or Service Pack 2.

2) The passwords - people often overlook, but well thought of passwords is an important part of their safety. The password must be at least 8 characters with a mixture of text, symbols and numbers. At a minimum, ensure that services are most at risk, a strong password. These services include a bank, credit card, other financial services such as PayPal, e-mail and other services such as Ebay, the chipper to generate profits.

3) anti-virus protection - but it is fair to say that the threat of computer viruses in recent years has decided not to put more serious harm to your computer. Part of the reason for the reduction of threats, because PC manufacturers are grouping more anti-virus package with his new team. For example, last year launched my new Dell with a 90-day trial of McAfee Internet Security Suite. The best way is a security suite, firewall and anti-virus software as a minimum purchase closes. leading brands include products from McAfee and Symantec Norton. However, Microsoft has recently been in the market with "OneCare" pricing is very aggressive.

4) firewall - if you have a broadband connection with the operation of a specific request for firewall traffic between your computer and the Internet. A firewall monitors incoming traffic, the gateway to the Internet on the computer. The best products also check outgoing traffic from your computer to the Internet. Therefore, the best option is to buy a firewall program as part of a security package that most companies offer as standard. If a hardware firewall as part of your router, then you need anything else. A company called Zone Labs offers a great free product called Zone Alarm firewall that uses a minimum. Windows XP now monitor does not have a free firewall, but the product of outgoing communications, and then I do not think they have to offer sufficient protection.

5) anti-spyware tool - this software is the culmination of their Internet security base established. This tool helps in the fight against spyware and adware. There is a good mix of free and paid versions. good free software is Microsoft Windows Defender, Spybot S & D and Ewido Anti-Malware. Ewido Anti-Malware is often recommended for computer help forum. Be careful if you decide to purchase a solution. There are a number of unscrupulous traders, the aggressive push products that have little value. Keep faith with names like Webroot Spy Sweeper or PC Tools Spyware Doctor. These products are good for independent testing.