网络管理

Linux系统配置及服务管理_第15章 网络管理
简介
网络接口名称规则
Network interface names

Traditionally, network interfaces in Linux are enumerated as eth0, eth1, eth2, and so on. However, the mechanism which
sets these names can cause changes to which interface gets which name as devices are added and removed.
The default naming behavior in Red Hat Enterprise Linux 7 is to assign fixed names based on firmware, device topology,
and device type.

Interface names have the following characters:
Ethernet interfaces begin with en, WLAN interfaces begin with wl, and WWAN interfaces begin with ww.
The next character(s) represents the type of adapter with an o for on-board, s for hotplug slot, and p for PCI geographic location.
Not used by default but also available to administrators, an x is used to incorporate a MAC address.
Finally, a number N is used to represent an index, ID, or port.
If the fixed name cannot be determined, the traditional names such as ethN will be used.

For example, the first embedded network interface may be named eno1 and a PCI card network interface may be named enp2s0.
The new names make it easier to distinguish the relationship between a port and its name if the user knows both, but the
trade off is that users cannot assume a system with one interface calls that interface eth0.

en:eethernet 以太网-双绞线
wl:wirelessLAN：无线网卡
ww：WAN广域网：串行线缆

o：on-board板载网卡
s:hotplug热插拔
p：PCI接口

N：序号或者ID

示例：enp2s0
NetworkManager服务
网络管理器（NetworkManager）是一个动态网络的控制器与配置系统，它用于当网络设备可用时保持设备和连接开启并激活
默认情况下，CentOS/RHEL 7 已安装网络管理器，并处于启用状态。
systemctl status NetworkManager
systemctl status network
配置网络的工具
命令，字符，图形
配置文件：vim
命令行：nmcli
简易图形： nmtui
图形界面：nm-connection-editor


配置网络参数
配置IP
方法一
[root@tianyun ~]# vim /etc/sysconfig/network-scripts/ifcfg-enp2s0
NAME="enp2s0"
DEVICE="enp2s0"
ONBOOT=yes //是否启用该设备
BOOTPROTO=none //手动(none/static)还是自动(dhcp)
IPADDR=172.16.120.246 //地址
PREFIX=24 //掩码
IPADDR1=192.168.200.246 //额外地址
PREFIX1=24 //额外掩码，注意编号
GATEWAY=172.16.120.254 //网关
DNS1=8.8.8.8 //DNS
DNS2=114.114.114.114 //DNS2
[root@tianyun ~]# nmcli con reload
[root@tianyun ~]# nmcli con down enp2s0; nmcli con up enp2s0
注：删除自建的连接connection
方法二（了解）
1. 方法二： 修改ip/netmask/dns/gateway[了解]
1 创建配置文件
nmcli connection add con-name eth0-1 autoconnect yes ifname eth0 type ethernet
2 设置IP地址
nmcli connection modify eth0-1 +ipv4.addresses 20.20.20.20/24
3 设置获取地址的方式为手动
nmcli connection modify eth0-1 ipv4.method m
4 启动该配置
nmcli connection up eth0-1
5 删除该配置
nmcli connection delete eth0-1
6 查看启动的设备和连接关系
nmcli device
特殊情况，不使用NetworkManager管理网络
aliyun
aliyun
[root@aliyun ~]# nmcli connection delete enp2s0-auto
[root@aliyun ~]# systemctl disable NetworkManager
[root@aliyun ~]# systemctl stop NetworkManager
[root@aliyun ~]# systemctl status NetworkManager
● NetworkManager.service - Network Manager
Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service; disabled; vendor preset: enabled)
Active: inactive (dead)

[root@aliyun ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0
NAME=eth0
DEVICE=eth0
ONBOOT=yes
NETBOOT=yes
BOOTPROTO=none
IPADDR=192.168.122.169
PREFIX=24
TYPE=Ethernet
[root@aliyun ~]# systemctl restart network.service

以下配置跟NetworkManager无关：
主机名
1. 修改主机名/etc/hostname
# hostnamectl set-hostname tianyun.example.com
# cat /etc/hostname
# reboot
域名解析
a. hosts
a. hosts方法，在本地服务器设置域名和IP的对应关系。方便临时使用域名访问某台服务器。
[root@tianyun ~]# cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
119.75.218.70 www.baidu.com
[root@tianyun ~]# getent hosts www.baidu.com
119.75.218.70 www.baidu.com

b. resolv.conf DNS
b. resolv.conf 将域名解析请求转发给DNS服务器。
[root@tianyun ~]# cat /etc/resolv.conf
# Generated by NetworkManager
nameserver 114.114.114.114

网络测试
测试工具
基本的网络测试工具

[root@tianyun ~]# ip a //查看所有IP
[root@tianyun ~]# ip a s eth0 //查看一个网卡
[root@tianyun ~]# ip route //查看路由
[root@tianyun ~]# ip neigh //另一台主机ping通
[root@tianyun ~]# hostname //主机名
[root@tianyun ~]# ping www.baidu.com
[root@tianyun ~]# ping -c2 www.baidu.com
[root@tianyun ~]# ip -s link show eth0 //转发的数据字节
[root@tianyun ~]# traceroute www.sina.com //跟踪路由
[root@tianyun ~]# tracepath www.sina.com

查看设备物理连接的状态
[root@tianyun ~]# ip a

如果在连接禁用 onboot=no 以上的信息不真实

[root@tianyun ~]# ethtool ens34
ports and services
安装示例服务
以下为示例服务：
[root@aliyun ~]# yum -y install httpd vsftpd
[root@aliyun ~]# systemctl start httpd
[root@aliyun ~]# systemctl start vsftpd

http 80/tcp
https 443/tcp
ssh 22/tcp
ftp 21/tcp

Show TCP sockets
1. Show TCP sockets (LISTEN)
[root@aliyun ~]# ss -tnl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:80 *:*
LISTEN 0 128 *:8080 *:*
LISTEN 0 10 114.215.71.214:53 *:*
LISTEN 0 10 10.29.89.165:53 *:*
LISTEN 0 10 127.0.0.1:53 *:*
LISTEN 0 128 *:22 *:*
LISTEN 0 128 127.0.0.1:953 *:*
LISTEN 0 128 127.0.0.1:6010 *:*
LISTEN 0 128 *:443 *:*
LISTEN 0 32 :::21 :::*
LISTEN 0 10 :::53 :::*

[root@aliyun ~]# ss -tnl |grep :80
LISTEN 0 128 *:80 *:*
[root@aliyun ~]# ss -tnl |grep :21
LISTEN 0 32 :::21 :::*

[root@aliyun ~]# ss -atn
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:80 *:*
LISTEN 0 10 114.215.71.214:53 *:*
LISTEN 0 10 10.29.89.165:53 *:*
LISTEN 0 10 127.0.0.1:53 *:*
LISTEN 0 128 *:22 *:*
LISTEN 0 128 127.0.0.1:953 *:*
LISTEN 0 128 127.0.0.1:6010 *:*
ESTAB 0 52 114.215.71.214:22 123.120.38.233:49603
ESTAB 0 0 114.215.71.214:40962 140.205.140.205:80
LISTEN 0 32 :::21 :::*
LISTEN 0 10 :::53 :::*

[root@aliyun ~]# ss -atn |grep :22
LISTEN 0 128 *:22 *:*
ESTAB 0 52 114.215.71.214:22 123.120.38.233:49603

[root@aliyun ~]# ss -atn |grep :80
LISTEN 0 128 *:80 *:*
ESTAB 0 0 114.215.71.214:40962 140.205.140.205:80
a 所有状态，包括 l LISTEN

Show UDP sockets
2. Show UDP sockets (所有状态)
[alice@tianyun ~]$ ss -anu
State Recv-Q Send-Q Local Address:Port Peer Address:Port
UNCONN 0 0 114.215.71.214:53 *:*
UNCONN 0 0 10.29.89.165:53 *:*
UNCONN 0 0 127.0.0.1:53 *:*
UNCONN 0 0 114.215.71.214:123 *:*
UNCONN 0 0 10.29.89.165:123 *:*
UNCONN 0 0 127.0.0.1:123 *:*
UNCONN 0 0 *:123 *:*
UNCONN 0 0 :::53 :::*
UNCONN 0 0 :::123 :::*

[kiosk@foundation0 ~]$ ss -tan |grep :5910
LISTEN 0 5 *:5910 *:*
ESTAB 0 0 172.25.254.250:5910 172.25.254.44:51435
ESTAB 0 0 172.25.254.250:5910 172.25.254.6:40546
ESTAB 0 0 172.25.254.250:5910 172.25.254.18:37780
ESTAB 0 0 172.25.254.250:5910 172.25.254.13:55841
ESTAB 0 0 172.25.254.250:5910 172.25.254.35:36984
ESTAB 0 0 172.25.254.250:5910 172.25.254.9:47342
ESTAB 0 0 172.25.254.250:5910 172.25.254.2:40955
ESTAB 0 0 172.25.254.250:5910 172.25.254.12:50833
ESTAB 0 0 172.25.254.250:5910 172.25.254.36:50854
ESTAB 0 0 172.25.254.250:5910 172.25.254.1:52444
ESTAB 0 0 172.25.254.250:5910 172.25.254.47:39335
ESTAB 10 0 172.25.254.250:5910 172.25.254.14:55833

临时配置网络信息
目的：
当临时使用某个IP或者网关时，可以使用如下命令。重启服务失效
ip/netmask

ip/netmask
# ip addr add dev eth1 3.3.3.3/24
# ip addr del dev eth1 3.3.3.3/24
# ip add s 查询
gateway
gateway
# ip route del default
# ip route add default via 192.168.122.3
# ip route add 10.10.10.0/24 via 192.168.122.5

hostname
hostname
# hostname QF.com
扩展
已经装好系统CentOS7修改网卡为eth0
1. 修改网卡配置文件
# mv ifcfg-eno16777728 ifcfg-eth0
# vim ifcfg-eth0
DEVICE=eth0  
NAME=eth0  

2. GRUB添加kernel参数
# vim /etc/sysconfig/grub
GRUB_CMDLINE_LINUX="...... net.ifnames=0"

3.重新装载配置文件
# grub2-mkconfig -o /boot/grub2/grub.cfg

4. reboot
# reboot

未装好系统CentOS7修改网卡为eth0
也可在安装系统时添加kernel参数 net.ifnames=0


KVM安装Centos7时将网卡改为eth0:(略)

在KVM虚拟机添加全虚拟化的网卡（略）

半虚拟化的网卡命名为eth0,1
全虚拟化的是ens9，新规则
VLSM
vlan/trunk