Possible Linux Network Attacks and security defense policies

Possible types of attacks on Linux Network

"Denial of Service" Attack

The so-called "Denial of Service" attack means that hackers use destructive methods to block the resources of the target network, temporarily or permanently paralyze the network, so that the Linux network server cannot provide services for normal users. For example, hackers can simultaneously send a large number of consecutive TCP/IP requests to the target computer using a forged source address or multiple computers in a controlled place, thus paralyzing the target server system.

Password cracking attack

Password security is the first line of defense to protect your system security. Password cracking attacks aim to crack users' passwords and obtain encrypted information resources. For example, hackers can use a high-speed computer and a dictionary library to try a combination of various passwords until they finally find the password that can enter the system and open network resources.

"Spoofing users" Attack

A "spoofing user" attack refers to a network hacker disguised as an engineering technician of a network company or computer service provider, who sends a call to the user and requires the user to enter a password when appropriate, this is one of the most difficult ways for users to deal with. Once a user's password is compromised, hackers can use the user's account to access the system.

"Scanner and network listener" Attacks

Many network intrusions start with scanning. Hackers can use scanning tools to identify various vulnerabilities on the target host and use them to launch system attacks.

Network listening is also a common method for hackers. After successfully logging on to a host on the network and obtaining the superuser control of the host, hackers can use network monitoring to collect sensitive data or authentication information, so as to seize control of other hosts on the network in the future.

Linux Network Security Protection Policy

Looking at the development history of the network, we can see that attacks on the network may come from illegal users or legal users. Therefore, as the administrator of a Linux network system, you must always be vigilant against external hacker attacks and strengthen management and education for internal network users. The following security policies can be used.

Carefully set the permissions of each internal user

To protect Linux network system resources, when setting up an account for an internal network user, you should carefully set the permissions for each internal user. Generally, the "minimum permission" principle should be followed, that is, only each user is granted the server access permissions required to complete their specific tasks. This will greatly increase the management workload of the system administrator, but this principle should be adhered to for the security of the entire network system.

Ensure the security of the user password file/etc/shadow

For network systems, passwords are prone to problems. As a system administrator, users should be notified to use secure passwords when setting passwords (using non-letters in the password sequence, special characters such as numbers), and increase the password length (more than 6 characters ). The system administrator needs to protect the security of the files/etc/passwd and/etc/shadow, so that irrelevant persons are not allowed to obtain the files, in this way, hackers use programs such as John to conduct dictionary attacks on the/etc/passwd and/etc/shadow files to obtain user passwords. The system administrator should periodically use John and other programs to simulate dictionary attacks on the/etc/passwd and/etc/shadow files of the system. Once an insecure user password is found, force the user to modify it immediately.

Strengthen monitoring and recording of system operations

The Linux network system administrator should monitor and record the running status of the entire network system, so that suspicious network activities can be found through analysis and record data, and take measures to prevent potential intrusion in advance. If the attack has been committed, you can track and identify hackers who intrude into the system using the recorded data.

Rationally divide subnets and set firewalls

If the internal network needs to enter the Internet, you must set a firewall at the interface between the internal network and the external network to ensure data security in the internal network. For the internal network itself, in order to facilitate management and rationally allocate IP Address Resources, the internal network should be divided into multiple subnets. This can also prevent or delay hacker intrusion into the entire internal network.

Perform regular security checks on Linux Networks

The operation of the Linux network system is dynamic, so its security management is also changing. There is no fixed mode. as the administrator of the Linux network system, after a security protection policy is set for the system, the system should be regularly inspected for security and attacks should be attempted against the server managed by itself. If any vulnerability in the security mechanism is found, measures should be taken to remedy the problem immediately, hackers are not allowed to take the opportunity.

Develop appropriate data backup plans to ensure the system is secure

No operating system is reliable, and no security policy is foolproof. Therefore, as a Linux system administrator, you must develop an appropriate data backup plan for the system, make full use of tape drives, disc recorders, dual-host hot backup and other technical means to save data backups for the system, so that once the system is damaged or paralyzed by hacker attacks, it can quickly restore the work, minimize the loss.

The possible attacks and security policies on Linux networks have been introduced to you. I hope you can understand them.