Network Tools and Diagnostics

网络工具与诊断

Overview

概述

Linux network diagnostics, port scanning, traffic analysis and other tool usage skills.

Linux网络诊断、端口扫描、流量分析等工具的使用技巧。

Network Configuration

网络配置

View Configuration

查看配置

bash

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bash

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IP address

IP地址

ip addr ip a ifconfig # Legacy command

ip addr ip a ifconfig # 旧版命令

Routing table

路由表

ip route route -n netstat -rn

DNS configuration

DNS配置

cat /etc/resolv.conf systemd-resolve --status

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cat /etc/resolv.conf systemd-resolve --status

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Configure Network

配置网络

bash

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bash

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Temporary IP configuration

临时IP配置

ip addr add 192.168.1.100/24 dev eth0 ip addr del 192.168.1.100/24 dev eth0

Enable/Disable interface

启用/禁用网卡

ip link set eth0 up ip link set eth0 down

Add route

添加路由

ip route add 10.0.0.0/8 via 192.168.1.1 ip route del 10.0.0.0/8

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ip route add 10.0.0.0/8 via 192.168.1.1 ip route del 10.0.0.0/8

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Connectivity Testing

连通性测试

ping

bash

ping hostname
ping -c 4 hostname                  # Send 4 packets
ping -i 0.2 hostname                # 0.2 second interval
ping -s 1000 hostname               # Specify packet size

bash

ping hostname
ping -c 4 hostname                  # 发送4个数据包
ping -i 0.2 hostname                # 间隔0.2秒
ping -s 1000 hostname               # 指定数据包大小

traceroute

bash

traceroute hostname
traceroute -n hostname              # Don't resolve hostnames
traceroute -T hostname              # Use TCP
mtr hostname                        # Real-time trace

bash

traceroute hostname
traceroute -n hostname              # 不解析主机名
traceroute -T hostname              # 使用TCP协议
mtr hostname                        # 实时追踪

DNS Query

DNS查询

bash

nslookup hostname
dig hostname
dig +short hostname
dig @8.8.8.8 hostname               # Specify DNS server
host hostname

bash

nslookup hostname
dig hostname
dig +short hostname
dig @8.8.8.8 hostname               # 指定DNS服务器
host hostname

Ports and Connections

端口与连接

ss Command (Recommended)

ss命令（推荐）

bash

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Listening ports

监听端口

ss -tlnp # TCP listening ss -ulnp # UDP listening ss -tlnp | grep :80

ss -tlnp # TCP监听端口 ss -ulnp # UDP监听端口 ss -tlnp | grep :80

All connections

所有连接

ss -tanp # TCP connections ss -s # Statistics

ss -tanp # TCP连接 ss -s # 统计信息

Filter

过滤

ss -t state established ss -t dst 192.168.1.1 ss -t sport = :80

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ss -t state established ss -t dst 192.168.1.1 ss -t sport = :80

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netstat Command

netstat命令

bash

netstat -tlnp                       # TCP listening
netstat -ulnp                       # UDP listening
netstat -anp                        # All connections
netstat -s                          # Statistics

bash

netstat -tlnp                       # TCP监听端口
netstat -ulnp                       # UDP监听端口
netstat -anp                        # 所有连接
netstat -s                          # 统计信息

lsof Network

lsof网络相关

bash

lsof -i                             # All network connections
lsof -i :80                         # Specific port
lsof -i tcp                         # TCP connections
lsof -i @192.168.1.1                # Specific host

bash

lsof -i                             # 所有网络连接
lsof -i :80                         # 指定端口
lsof -i tcp                         # TCP连接
lsof -i @192.168.1.1                # 指定主机

HTTP Tools

HTTP工具

curl

bash

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Basic request

基础请求

curl http://example.com curl -I http://example.com # Headers only curl -v http://example.com # Verbose output

curl http://example.com curl -I http://example.com # 仅获取响应头 curl -v http://example.com # 详细输出

POST request

POST请求

curl -X POST -d "data=value" http://example.com curl -X POST -H "Content-Type: application/json" -d '{"key":"value"}' http://example.com

Download

下载文件

curl -O http://example.com/file.zip curl -o output.zip http://example.com/file.zip

Authentication

身份验证

curl -u user:pass http://example.com curl -H "Authorization: Bearer token" http://example.com

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curl -u user:pass http://example.com curl -H "Authorization: Bearer token" http://example.com

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wget

bash

wget http://example.com/file.zip
wget -c http://example.com/file.zip # Resume download
wget -r http://example.com          # Recursive download
wget --mirror http://example.com    # Mirror site

bash

wget http://example.com/file.zip
wget -c http://example.com/file.zip # 断点续传
wget -r http://example.com          # 递归下载
wget --mirror http://example.com    # 镜像站点

Packet Capture

数据包捕获

tcpdump

bash

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Basic capture

基础捕获

tcpdump -i eth0 tcpdump -i any

Filter

过滤规则

tcpdump -i eth0 port 80 tcpdump -i eth0 host 192.168.1.1 tcpdump -i eth0 'tcp port 80 and host 192.168.1.1'

Save/Read

保存/读取捕获文件

tcpdump -i eth0 -w capture.pcap tcpdump -r capture.pcap

Display content

显示内容

tcpdump -i eth0 -A port 80 # ASCII tcpdump -i eth0 -X port 80 # Hexadecimal

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tcpdump -i eth0 -A port 80 # ASCII格式 tcpdump -i eth0 -X port 80 # 十六进制格式

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Traffic Monitoring

流量监控

bash

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Real-time traffic

实时流量监控

iftop iftop -i eth0

By process

按进程统计流量

nethogs nethogs eth0

Bandwidth test

带宽测试

iperf3 -s # Server iperf3 -c server_ip # Client

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iperf3 -s # 服务器端 iperf3 -c server_ip # 客户端

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Common Scenarios

常见场景

Scenario 1: Troubleshoot Port Usage

场景1：排查端口占用

bash

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Check port usage

检查端口占用情况

ss -tlnp | grep :8080 lsof -i :8080

Find process and handle

找到进程并处理

kill -9 PID

Or

或者

fuser -k 8080/tcp

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fuser -k 8080/tcp

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Scenario 2: Test Service Connectivity

场景2：测试服务连通性

bash

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TCP port test

TCP端口测试

nc -zv hostname 80 telnet hostname 80

HTTP service test

HTTP服务测试

curl -I http://hostname curl -w "HTTP Code: %{http_code}\nTime: %{time_total}s\n" -o /dev/null -s http://hostname

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curl -I http://hostname curl -w "HTTP状态码: %{http_code}\n耗时: %{time_total}s\n" -o /dev/null -s http://hostname

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Scenario 3: Network Performance Diagnosis

场景3：网络性能诊断

bash

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Latency test

延迟测试

ping -c 100 hostname | tail -1

Route analysis

路由分析

mtr --report hostname

Bandwidth test

带宽测试

iperf3 -c server -t 30

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iperf3 -c server -t 30

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Troubleshooting

故障排查

Problem	Solution
Network unreachable	`ping` , `traceroute` , check routing
DNS resolution failed	`dig` , `nslookup` , check resolv.conf
Port unreachable	`ss -tlnp` , check firewall
Connection timeout	`mtr` , `tcpdump` packet capture
Insufficient bandwidth	`iftop` , `iperf3` test

问题	解决方案
网络不可达	使用 `ping` 、 `traceroute` ，检查路由配置
DNS解析失败	使用 `dig` 、 `nslookup` ，检查resolv.conf配置
端口不可访问	使用 `ss -tlnp` ，检查防火墙设置
连接超时	使用 `mtr` 、 `tcpdump` 捕获数据包
带宽不足	使用 `iftop` 、 `iperf3` 进行测试

network-tools

Original

Translation

Network Tools and Diagnostics

网络工具与诊断

Overview

概述

Network Configuration

网络配置

View Configuration

查看配置

IP address

IP地址

Routing table

路由表

DNS configuration

DNS配置

Configure Network

配置网络

Temporary IP configuration

临时IP配置

Enable/Disable interface

启用/禁用网卡

Add route

添加路由

Connectivity Testing

连通性测试

ping

ping

traceroute

traceroute

DNS Query

DNS查询

Ports and Connections

端口与连接

ss Command (Recommended)

ss命令（推荐）

Listening ports

监听端口

All connections

所有连接

Filter

过滤

netstat Command

netstat命令

lsof Network

lsof网络相关

HTTP Tools

HTTP工具

curl

curl

Basic request

基础请求

POST request

POST请求

Download

下载文件

Authentication

身份验证

wget

wget

Packet Capture

数据包捕获

tcpdump

tcpdump

Basic capture

基础捕获

Filter

过滤规则

Save/Read

保存/读取捕获文件

Display content

显示内容

Traffic Monitoring

流量监控

Real-time traffic

实时流量监控

By process

按进程统计流量

Bandwidth test