Ubuntu18.04之网络配置+域名配置+软件源配置+ssh免密登陆

网络配置

ubuntu 18.04网络配置较之前版本有较大改动，它弃用了/etc/networks/interface配置，真正的网络配置是在/etc/netplan/xxx.yaml中生效

查看当前系统网口连结状态，使用

ip a

查看对应网口，如果状态不是down而是up,则选择改网口进行配置

编辑/etc/netplan/xxx.yaml

#注意，如果每个配置后面有内容，则:号后面需加一个空格，再加入自己的配置项
network:
  version: 2
  rendderer: NetworkManager
  ethernets:
    enp24s0f0:  #以上都不用修改，这里为我们确认的up状态的网口
    dhcp4: no #如果我们想要自动分配ip，则更改为yes，并且后面都不用配置。这里设置为no，表示ip是静态手动分配的，需进行后续配置
    addresses: [10.192.55.178/24] #这里配置ip地址
    gateway4: 10.192.55.254 #配置网关

配置外网域名访问 (前提是开通外网权限)

编辑/etc/resolv.conf

#增加如下配置
nameserver 114.114.114.114 #电信免费提供的DNS服务器
nameserver 8.8.8.8 #谷歌提供的免费dns公众服务器
nameserver 118.118.118.55 #四川雅安电信的公众服务器

编辑/etc/systemd/resolved.conf修改文件，将DNS前的#符号去掉，再加上DNS服务器地址

[resolve]
DNS=114.114.114.114
DNS=118.118.118.55
DNS=8.8.8.8

保存退出后执行/etc/init.d/networking force-reload 重新加载网络相关的配置文件，使DNS配置生效

验证如下：

ping 114.114.114.114能够ping通，如果无法ping通，则外网权限未开

ping www.baidi.com能够ping通。如果无法ping通，则检查配置文件是否填写正确

配置软件源（使用国内源）

备份当前源mv /etc/apt/source.lit /etc/apt/source.list-bak

编辑vi /etc/apt/source.list

插入如下内容，总共提供了四个源（阿里，网易，中科，清华），可以只选择一个源

#阿里源
deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
#中科源
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
#网易源
deb http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse
#清华源
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-poposed main restricted universe multiverse

更新当前源sudo apt-get update即可

配置远程ssh访问

检测当前系统是否有sshd进程存在

ps -ef|grep ssh查看是否存在sshd进程，如果存在，则可以直接ssh访问当前设备。如果不存在则执行如下步骤

安装ssh软件

sudo apt-get install -y openssh-server

再次检查是否进程sshd存在，存在则可以继续访问

ssh 主机名如果能够正常访问，则表示当前设备已经支持ssh访问

设置ssh本机免密登录，执行如下

ssh-keygen
cd ~/.ssh
cat .ssh/id_rsa.pub >> .ssh/authorized_keys
chmod 600 .ssh/authorized_keys

重启ssh服务，我们输入： /etc/init.d/ssh restart
验证是否成功:
ssh 主机名 即可不需要密码成功登录

设置hostname

hostnamectl set-hostname node1  
hostnamectl set-hostname node2  
hostnamectl set-hostname node3

修改/etc/hosts文件

192.168.113.3 node1  
192.168.113.4 node2  
192.168.113.5 node3

设置ssh免密登录

ssh-keygen 一路回车  
ssh-copy-id node{1,2,3}

验证一下

ssh node2

有3台虚拟机：

192.168.178.137   bigdata-cdh01.ibeifeng.com 
192.168.178.138   bigdata-cdh02.ibeifeng.com
192.168.178.139   bigdata-cdh03.ibeifeng.com
以 bigdata-cdh01.ibeifeng.com 主机做操作：

用root用户登录；

运行命令：ssh-keygen -t rsa，一直按回车直到结束；生成密码对；

# ssh-keygen -t rsa

Generating public/private rsa key pair.
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
ee:4e:12:b5:f1:e3:92:ed:b8:f3:78:76:a0:11:30:0f root@bigdata-cdh01.ibeifeng.com
The key’s randomart image is:
±-[ RSA 2048]----+
| |
| E |
| =o |
| .o+ |
| . S.o |
| o.+… |
| . =oo. |
| +o=o . |
| .**o. |
±----------------+
进入生成的 ~/.ssh 目录；可以看到有2个文件；

id_rsa.pub 是公钥，可以发送到其他机子，用于加密；

id_rsa 是私钥，只能保存在本机，用于解密；

# cd ~/.ssh

id_rsa id_rsa.pub
把公钥追加到 authorized_keys 文件

# cat id_rsa.pub >> authorized_keys

测试能不能免密登陆到本机；

可以看到第一次有警告；第二次就可以免密登录；

# ssh bigdata-cdh01.ibeifeng.com

The authenticity of host ‘bigdata-cdh01.ibeifeng.com (192.168.178.137)’ can’t be established.
RSA key fingerprint is bd:4f:95:ba:38:b6:97:b7:5a:95:d2:76:41:07:cb:e7.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added ‘bigdata-cdh01.ibeifeng.com,192.168.178.137’ (RSA) to the list of known hosts.
Last login: Tue Dec 3 10:46:04 2019 from 192.168.178.1

# exit

logout
Connection to bigdata-cdh01.ibeifeng.com closed

# ssh bigdata-cdh01.ibeifeng.com

Last login: Tue Dec 3 12:54:49 2019 from bigdata-cdh01.ibeifeng.com

# exit

logout
Connection to bigdata-cdh01.ibeifeng.com closed.
同时在 bigdata-cdh02.ibeifeng.com 和 bigdata-cdh03.ibeifeng.com 做以上操作；

分别把bigdata-cdh02.ibeifeng.com 和 bigdata-cdh03.ibeifeng.com 的公钥发送到 bigdata-cdh01.ibeifeng.com 的 authorized_keys中，

# cat ~/.ssh/id_rsa.pub | ssh bigdata-cdh01.ibeifeng.com 'cat >> ~/.ssh/authorized_keys'

此时，bigdata-cdh01.ibeifeng.com 的 authorized_keys中 同时有 bigdata-cdh01、bigdata-cdh02 和 bigdata-cdh03 的 公钥，可以免密码登录 bigdata-cdh01、bigdata-cdh02 和 bigdata-cdh03；

把bigdata-cdh01.ibeifeng.com中的 authorized_keys 发送到 bigdata-cdh02 和 bigdata-cdh03 的 ~/.ssh/ 目录下；

使得 bigdata-cdh02 和 bigdata-cdh03 都有三台主机的公钥；这样，三台主机都互相拥有对方的公钥，可以相互免密登录；

# scp -r authorized_keys root@bigdata-cdh02.ibeifeng.com:~/.ssh/