Article directory

Linux Networking and Security
Summarize
Recommended Python boutique columns
- Basic knowledge of python (0 basic introduction)
- python crawler knowledge

Linux Networking and Security

introduction

In Linux operating system, network and security are very important aspects. This article will introduce some key elements to help newbies understand and apply these concepts.

Network Configuration

IP address configuration

In Linux, configuring an IP address is the first step in connecting to the network. You can specify a static IP address by editing the network configuration file, or use DHCP to automatically assign an IP address.

$ sudo vi /etc/network/interfaces

# 静态IP地址配置示例
auto eth0
iface eth0 inet static
address 192.168.1.100
netmask 255.255.255.0
gateway 192.168.1.1

Configure network interface

Configuring the network interface allows us to set different network parameters, such as subnet mask, gateway, DNS server, etc.

$ sudo ifconfig eth0 up           # 启用网络接口
$ sudo ifconfig eth0 down         # 禁用网络接口
$ sudo ifconfig eth0 192.168.1.2  # 设置IP地址

Firewall settings

Firewalls protect our computers from cyberattacks. By configuring firewall rules, we can limit data traffic in and out of the network.

$ sudo ufw enable              # 启用防火墙
$ sudo ufw allow ssh           # 允许SSH连接
$ sudo ufw allow 80/tcp        # 允许HTTP访问
$ sudo ufw status              # 查看防火墙状态

Enhanced security

In order to enhance the security of remote connections, we can set it up through the following methods.

Log in using an SSH key: Generate a key pair and add the public key to ~/.ssh/authorized_keysa file on the remote host.
Disable root user remote login: modify the SSH configuration file /etc/ssh/sshd_configand PermitRootLoginset it to no.
Use a firewall to restrict remote access: only allow hosts with specific IP addresses or IP ranges to access the SSH port.

Linux network configuration and port management

In Linux, we can use some commands and tools to configure network and management ports.

Network configuration commands

ifconfig: Display and configure network interface information.
ip: Can replace ifconfig, providing more advanced functions.

$ ifconfig eth0           # 显示eth0接口信息
$ ifconfig eth0 up        # 启用eth0接口
$ ifconfig eth0 down      # 禁用eth0接口

Port management

In Linux, we can use netstatthe command to see the ports in use.

$ netstat -tuln           # 列出所有监听端口
$ netstat -tunlp          # 列出所有监听端口及其进程信息

Firewall and security settings

Firewall management tools

There are many firewall management tools to choose from in Linux, such as ufw, iptablesetc.

$ sudo ufw enable        # 启用防火墙
$ sudo ufw status        # 查看防火墙状态
$ sudo ufw allow 22      # 允许SSH连接

Security settings

In order to enhance the security of the system, we can take some measures, such as regularly updating the system, using complex passwords, disabling unnecessary services, etc.

$ sudo apt update        # 更新软件包
$ passwd                 # 修改用户密码
$ sudo systemctl disable service-name    # 禁用不必要的服务

Linux remote access technologies: SSH and VPN

SSH

SSH (Secure Shell) is a protocol for secure remote login on an unsecured network through encryption.

$ ssh username@remote_host   # SSH登录到远程主机
$ scp file.txt remote_host:  # 使用SCP命令复制文件到远程主机

VPN

VPN (Virtual Private Network) can establish a private, encrypted connection through a public network to achieve remote access to internal networks.

Linux software and services

In Linux, there are a wide variety of software and services available. Here are some common software and services.

Apache HTTP server: used to build websites.
MySQL database: used to store and manage data.
Samba server: used to share files and printers between Linux and Windows.
FTP server: used to transfer files via FTP protocol.

Network tools

In addition to the previously mentioned commands and tools, there are some other commonly used network tools that can help you manage and debug network connections.

ping: Used to test connectivity with the target host.
nslookupOr dig: used to query domain name resolution records.
tracerouteOr mtr: used to trace the transmission path of data packets.
tcpdump: Used to capture and analyze network packets.
wgetOr curl: for downloading files via HTTP or FTP protocols.

file transfer

In addition to using SCP commands for file transfer, there are some other optional methods.

rsync: For efficient synchronization and backup of files and directories.
sftp: Secure file transfer based on SSH protocol.
ftp: Traditional FTP protocol file transfer.

VPN technology

VPN not only enables remote access to internal networks, but also enhances network security and privacy protection.

OpenVPN: Open source VPN software that supports multiple operating systems and encryption algorithms.
WireGuard: A modern, fast and secure VPN protocol.
IPSec: A suite of network protocols used to establish VPN connections, with various implementations such as StrongSwan and Libreswan.

Security auditing and log management

In order to monitor and identify potential security threats, we can perform security audits and log management.

auditd: Auditing framework for the Linux kernel, used to record system and application activities.
logrotate: Used to automatically rotate log files to prevent log files from becoming too large and occupying disk space.
fail2ban: Tools to detect malicious behavior and automatically ban attackers.

Intrusion detection and prevention

To protect the system from intrusions, we can use some intrusion detection and prevention tools.

Snort: An open source Network Intrusion Detection System (NIDS).
Tripwire: Intrusion detection tool for monitoring the integrity and changes of system files.
FirewallD: Dynamic firewall for configuring and managing Linux systems.

Software updates and bug fixes

Timely updating of software and fixing vulnerabilities are important measures to maintain system security.

aptOr yum: Package management tool for updating and installing software packages.
unattended-upgrades: Tool for automatically installing system and software updates.
OpenVAS: Open source vulnerability scanner for detecting security vulnerabilities in systems.

Other safety tips

Finally, here are some suggestions to strengthen the security of your systems and networks:

Use a password management tool to generate and store strong passwords.
Enable multi-factor authentication (MFA) for added security when logging in.
Back up important data regularly and store it offline.
Only download and install applications from trusted software sources.
Regularly review and update access control lists (ACLs) of network devices.

certainly! The following are some advanced Linux network and security knowledge points for you to continue learning:

Containerization and virtualization

Containerization and virtualization technologies can help you better manage and isolate applications and services.

Docker: A popular containerization platform that makes it easy to encapsulate applications and their dependencies and enable cross-platform deployment.
Kubernetes: An open source platform for automating container operations that simplifies container orchestration, scaling, and management.
Xen and KVM: Common virtualization solutions that can run multiple virtual machines on a single physical host.

IDS/IPS and firewalls

Intrusion detection systems (IDS) and intrusion prevention systems (IPS) and firewalls are key components of network security.

Suricata and Snort: Open source IDS/IPS systems for detecting and blocking network attacks.
pfSense and iptables: used to configure and manage firewall rules and network access control.
SELinux and AppArmor: Used to strengthen system security and limit process permissions.

Encryption and digital certificates

Encryption and digital certificates can be used to protect the confidentiality and integrity of data.

OpenSSL: A powerful open source encryption toolkit that supports a variety of cryptographic algorithms and protocols.
Let's Encrypt: Provides free SSL/TLS certificates for enabling HTTPS encrypted connections.
GnuPG: Open source tool for generating and managing public key encryption and digital signatures.

Security audit and compliance

Security audits and compliance checks are important steps in ensuring that systems comply with security standards and regulations.

Security Information and Event Management (SIEM): Solutions that centrally manage and analyze security events and logs, such as ELK Stack and Splunk.
CIS Benchmark: A configuration baseline published by CIS (Center for Internet Security), used to evaluate and strengthen system security.
PCI DSS: A security standard for organizations that process credit card information to ensure payment security.

Safety education and awareness

In addition to technical measures, safety education and awareness training are also crucial.

Provide employee security training to teach security best practices such as password management, social engineering, phishing attacks, etc.
Conduct regular security drills and simulated attacks to test system and personnel responsiveness.
Regularly evaluate and update security policies to ensure they remain consistent with the ever-changing threat environment.

Summarize

In this article, we explore various aspects of Linux networking and security. We started with network configuration, learning how to configure IP addresses and network interfaces, and how to set up firewalls to secure the system. We also explore how to harden your system's security, including network configuration commands, port management, and firewall and security settings.

Next we introduced Linux remote access technology, focusing on SSH and VPN. We learned how to use SSH for secure remote connections and learned how to set up and manage a VPN to establish a secure network connection.

We then moved on to Linux software and services, focusing specifically on networking tools, file transfers, and VPN technology. We take an in-depth look at various networking tools, as well as how to make secure file transfers and the importance of using VPN technology to protect data transfers.

In the Security Auditing and Log Management section, we discuss the importance of intrusion detection and prevention, as well as how to implement software updates and vulnerability fixes. In addition, we provide additional security advice, including containerization and virtualization technologies, IDS/IPS and firewalls, encryption and digital certificates, and the importance of security auditing and compliance.

Finally, we emphasize the importance of security education and awareness, including providing employee security training, conducting regular security drills and simulated attacks, and regularly evaluating and updating security policies.

Through the study of this article, we have an in-depth understanding of various aspects of Linux network and security, and learned the key technologies and best practices for protecting system and data security. Whether it is network configuration, remote access technology or security auditing and log management, we can take appropriate measures to strengthen system security. I hope that by studying these, you will become more confident and proficient in the field of Linux network and security!

Recommended Python boutique columns

Basic knowledge of python (0 basic introduction)

python crawler knowledge

[python crawler] 1. Basic knowledge of crawlers
[python crawler] 2. Basic knowledge of web pages
[python crawler] 3. First experience with crawlers (BeautifulSoup analysis)
[python crawler] 4. Practical crawler operation (dish crawling)
[python crawler] 5 .Practical crawler operation (crawling lyrics)
[python crawler] 6. Practical crawler operation (requesting data with parameters)
[python crawler] 7. Where is the crawled data stored?
[python crawler] 8. Review the past and learn the new
[python crawler] 9. Log in with cookies (cookies)
[python crawler] 10. Command the browser to work automatically (selenium)
[python crawler] 11. Let the crawler report to you on time
[python crawler] 12. Build your crawler army
[python crawler] 13. What to eat without getting fat (crawler practical exercise)
[python crawler] 14. Scrapy framework explanation
[python crawler] 15. Scrapy framework practice (popular job crawling Take)
[python crawler] 16. Summary and review of crawler knowledge points