Linux operating system optimization and Security (II)

Article Title: linux operating system optimization and Security (II ). Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.
　　 2. Hard Disk Optimization
　　
If you are using a scsi hard disk or an ide array, skip this section. The parameter adjustment described in this section is only applicable to servers that use an ide hard disk.
　　
We use the hdparm program to set the IDE hard disk,
　　
Using DMA and 32-bit transmission can greatly improve system performance. Run the following command:
　　
#/Sbin/hdparm-c 1/dev/hda
　　
This command specifies the PCI bus of the first IDE hard disk as 32-bit,
　　
Use the-c 0 parameter to disable 32-bit transmission.
　　
To use DMA on a hard disk, run the following command:
　　
#/Sbin/hdparm-d 1/dev/hda
　　
You can use the-d 0 parameter to disable DMA.
　　
After the modification is complete, you can use hdparm to check the modified result and run the following command:
　　
#/Sbin/hdparm-t/dev/had
　　
To ensure that the set results remain unchanged, run the following command:
　　
#/Sbin/hdparm-k 1/dev/hda
　　
Some common parameters of the Hdparm command
　　
-G: displays the disk's magnetic track, Head, magnetic area, and other parameters.
　　
-I displays the hardware specification information of the hard disk, which is provided by the hard disk itself at startup.
　　
-I directly reads the hardware specification information provided by the hard disk.
　　
-P: Set the PIO mode of the hard disk.
　　
-Tt evaluates the Read efficiency of the hard disk and the Read efficiency of the hard disk cache.
　　
-U <0 or 1> allows other interruption requests to be executed simultaneously during hard disk access.
　　
-V displays the hard disk settings.
　　
　　 3. Other Optimizations
　　
Disable unnecessary services. I will not go into details about the services automatically started by the system;
　　
　　 About Security
　　
　　 Security check
　　
As a system administrator, it is very important to perform a comprehensive security check on the system on a regular basis. Recently, some friends wrote that some inexplicable problems have occurred, for example, the biggest problem is that the network service is obviously slow, which is very likely to be attacked. Practice has proved that the default installation is not safe for any system. In fact, no matter whether you use windows, linux, bsd, or other systems, there are many vulnerabilities installed by default, so how can we become a secure system? This is exactly what our system administrators need to do. Configure and reconfigure. As long as you carefully configure any system and block known vulnerabilities, it can be said that the system is secure, not as many friends have said. They have installed the system, configured the firewall, and installed anti-virus software, so it is safe. In fact, if you do not set any security settings for the system, it is equivalent to opening a door to the hacker, which can be fully controlled in tens of minutes!
　　
This is not shocking.
　　
As a linux system, there are also many vulnerabilities that may be exploited to control your entire system. To prevent these vulnerabilities, we need to take the following steps:
　　
1. Upgrade the latest version of all software packages in the system;
　　
2. Set a strong firewall;
　　
3. Regularly check key record files and configure anti-virus software
　　
4. pay more attention to the websites that issue security information warnings, and master the characteristics of some of the latest viruses and hacker programs, which all benefit from the normal operation of the system.
　　
This article focuses on optimization. In order to cooperate with this topic, we will only discuss some daily maintenance work.
　　
In addition to the four listed above, they are required by administrators and are also important for the maintenance of some linux system details.
　　
　　 Including:
　　
1. configuring the log training tool and regularly downloading backup logs is a good habit. This not only reduces the disk space consumed by logs, but also improves system efficiency and can detect problems in a timely manner, some good system log analyzer in linux can directly extract special items in the log, saving the trouble of reading logs;
　　
2. Use the command lsof? Ci, netstat? Ca, ps? Ce and other commands, regularly check system service port listening and other conditions, you can also make a script for regular execution, these commands are regularly executed and then sent to the mailbox;
　　
3. regularly check the history list, last list, And vipw user list of the root user;
　　
4. Regularly Back Up Files and use the tar command to back up the files. Of course, you need to download these backups and transfer the media;
　　
If you find any special situations or ports that you have never seen before, pay enough attention to them.
　　
The above are some simple understandings of linux system security and optimization. I hope everyone can use linux safely and efficiently to bring convenience to your work and life.