配置网卡

• ubuntu17.10开始使用netplan来配置网络
• 传统的ifupdown已经被废弃,包括配套的配置文件/etc/network/interface
• ubuntu 18.04 lts的默认配置文件为/etc/netplan/50-cloud-init.yaml

0x1 启用 netplan

• netplan的配置文件夹为/etc/netplan,这里面包含了所有网卡的配置
• ubuntu 18.04 lts开始系统中内置了cloud-int服务,这个服务会自动修改netplan的网络配置

根据配置文件/etc/netplan/50-cloud-init.yaml中的提示,使用以下命令可以禁用cloud-int对网路的影响

echo "network: {config: disabled}" >/etc/cloud/cloud.cfg.d/99-disable-network-config.cfg

0x2 配置 netplan

1. netplan的配置文件是yaml格式的,这个格式 根据缩进来区分配置快
2. yaml是key: value的格式来指定配置,但是符号:后一定要先写 空格 再接value

0x2.1 配置dhcp

• 这是一段netplan的配置文件/etc/netplan/50-cloud-init.yaml

# This file is generated from information provided by the datasource.  Changes
# to it will not persist across an instance reboot.  To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    ethernets: 
            enp2s0:
                    dhcp4: yes
                    dhcp6: no
                    optional: true

            enp4s0:
                    dhcp4: yes
                    dhcp6: no
                    optional: true

    
    version: 2

• optional: true表示:这个网卡是可选的,开机时配置失败的话就直接跳过
• enp2s0和enp4s0是两张网卡(ip a查看所有网卡)

0x2.2 配置为 静态ip

# This file is generated from information provided by the datasource.  Changes
# to it will not persist across an instance reboot.  To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    ethernets: 
            enp2s0:
                dhcp4: no
                dhcp6: no
                addresses: [192.168.123.31/24]
                gateway4: 192.168.123.1
                nameservers:
                    addresses: [8.8.8.8, 8.8.4.4]

            enp4s0:
                    dhcp4: yes
                    dhcp6: no
                    optional: true

    
    version: 2

0x3 刷新网络

按照新的配置设置网络

netplan apply

刷新ip地址

• 在某些情况下需要重新获取 ip地址
• 建议配合 随机mac地址使用

dhclient

• 这里linux内置的方案,但某些接精简的系统上可能没有
• 路由器没有做 ip绑定的话一般情况下获得是同一个ip

# 首先 强制释放 eth0的ip地址
dhclient -r eth0

# 重新申请 ip地址
dhclient eth0

# 为所有网卡申请新的 ip地址
# dhclient

ifconfig

1. dhclient获取到的ip由路由器决定
2. 这里可以 使用 随机mac地址,强制路由器分配新的ip

# 随机生成mac地址
# mac地址有一些固定前缀,代表某些厂商和用途
# 完全随机生成的话会被识破
mac_tag="88:d7:f6:"
mac_add=$(date +%s|md5sum | sed 's/\(..\)/&:/g' | cut -c1-8)
new_mac="${mac_tag}${mac_add}"
# 需要修改的mac地址

echo "gen new mac: ${new_mac}"

nic=eth0
ifconfig $nic down
# sleep 3
ifconfig $nic hw ether "$new_mac"
# ifconfig $nic hw ether "88:D7:F6:25:d2:e2"
ifconfig $nic up

Configuring a network card

• ubuntu17.10 starts using netplan to configure the network
• The legacy ifupdown has been deprecated, including the companion configuration file /etc/network/interface
• ubuntu 18.04 lts default configuration file is /etc/netplan/50-cloud-init.yaml

0x1 Enable netplan

• The configuration folder for netplan is /etc/netplan, which contains the configuration for all network cards
• ubuntu 18.04 lts starts with a built-in cloud-int service, which will automatically modify the network configuration of netplan.

Following the instructions in the configuration file /etc/netplan/50-cloud-init.yaml, you can disable the effect of cloud-int on the network by using the following command

echo "network: {config: disabled}" >/etc/cloud/cloud.cfg.d/99-disable-network-config.cfg

0x2 configure netplan

1. the configuration file of netplan is in yaml format, which distinguishes the configuration fast according to the indentation
2. yaml is the key: value format to specify the configuration, but the symbol : must be followed by space and then value.

0x2.1 Configuring dhcp

• This is the netplan configuration file /etc/netplan/50-cloud-init.yaml

# This file is generated from information provided by the datasource. changes
# to it will not persist across an instance reboot. To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    ethernets: 
            enp2s0:
                    dhcp4: yes
                    dhcp6: no
                    optional: true

            enp4s0:
                    dhcp4: yes
                    dhcp6: no
                    optional: true

    
    version: 2

• optional: true means: this NIC is optional, if the configuration fails at boot time, just skip it
• enp2s0 and enp4s0 are two NICs (ip a to see all NICs)

0x2.2 configured as static ip

# This file is generated from information provided by the datasource. changes
# to it will not persist across an instance reboot. To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    ethernets: 
            enp2s0:
                dhcp4: no
                dhcp6: no
                addresses: [192.168.123.31/24]
                gateway4: 192.168.123.1
                nameservers:
                    addresses: [8.8.8.8, 8.8.4.4]

            enp4s0:
                    dhcp4: yes
                    dhcp6: no
                    optional: true

    
    version: 2

0x3 Refresh the network

Set up the network according to the new configuration

netplan apply

Refresh ip address

• In some cases it is necessary to reacquire the ip address
• recommended for use with random mac addresses

dhclient

• This is a built-in solution for Linux, but may not be available on some lite systems.
• if the router does not do ip binding, it usually gets the same ip

# First, force the release of eth0 ip address
dhclient -r eth0

# reapply ip address
dhclient eth0

# Apply new ip addresses for all NICs
# dhclient

ifconfig

1. the ip obtained by dhclient is determined by the router
   Here you can use random mac addresses to force the router to assign a new ip

# random mac address generation
# mac addresses have some fixed prefixes, representing certain vendors and uses
# Totally random generation will be detected
mac_tag="88:d7:f6:"
mac_add=$(date +%s|md5sum | sed 's/\(... \)/&:/g' | cut -c1-8)
new_mac="${mac_tag}${mac_add}"
# The mac address to be modified

echo "gen new mac: ${new_mac}"

nic=eth0
ifconfig $nic down
# sleep 3
ifconfig $nic hw ether "$new_mac"
# ifconfig $nic hw ether "88:D7:F6:25:d2:e2"
ifconfig $nic up