Ubuntu初次使用

Ubuntu初次使用

openssh安装

Ubuntu默认未安装openssh-server，会导致服务器IP配置后，IP能ping通，但ssh无法连接

1. 查看系统openssh是否安装

ubuntu@ubuntu:~$ dpkg -l | grep -i openssh
ii  openssh-client                             1:8.4p1-5ubuntu1                                                     amd64        secure shell (SSH) client, for secure access to remote machines
ubuntu@ubuntu:~$ 

2. apt安装

PS：apt安装后相关文件会存在/var/cache/apt/archives内，可拷贝出来后通过dpkg -i *.deb安装

buntu@ubuntu:~$ sudo apt-get install openssh-server

3. 再次查看openssh安装情况

ubuntu@ubuntu:~$ dpkg -l | grep -i openssh
ii  openssh-client                             1:8.4p1-5ubuntu1                                                     amd64        secure shell (SSH) client, for secure access to remote machines
ii  openssh-server                             1:8.4p1-5ubuntu1                                                     amd64        secure shell (SSH) server, for secure access from remote machines
ii  openssh-sftp-server                        1:8.4p1-5ubuntu1                                                     amd64        secure shell (SSH) sftp server module, for SFTP access from remote machines
ubuntu@ubuntu:~$ 

4. 查看openssh进程情况

ubuntu@ubuntu:~$ ps -ef | grep ssh
root         742       1  0 09:49 ?        00:00:00 sshd: /usr/sbin/sshd -D [listener] 0 of 10-100 startups
ubuntu      2864    2829  0 10:03 pts/1    00:00:00 grep --color=auto ssh
ubuntu@ubuntu:~$ 

5.简单防火墙状态

若防火墙状态开启，但22端口未开放，需开放22端口

ubuntu@ubuntu:~$ sudo ufw status
[sudo] password for ubuntu: 
Status: active

To                         Action      From
--                         ------      ----
22                         ALLOW       Anywhere                  
22 (v6)                    ALLOW       Anywhere (v6)             

ubuntu@ubuntu:~$ 
ubuntu@ubuntu:~$ 

开放端口命令

ubuntu@ubuntu:~$  sudo ufw allow 22

vim安装

apt安装

sudo apt-get install vim 

安装步骤记录

ubuntu@ubuntu:~$ dpkg -l | grep -i vim
ii  vim-common                                 2:8.2.2434-1ubuntu1                                                  all          Vi IMproved - Common files
ii  vim-tiny                                   2:8.2.2434-1ubuntu1                                                  amd64        Vi IMproved - enhanced vi editor - compact version
ubuntu@ubuntu-VirtualBox:~$ sudo apt-get install vim 
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
  vim-runtime
Suggested packages:
  ctags vim-doc vim-scripts
The following NEW packages will be installed:
  vim vim-runtime
0 upgraded, 2 newly installed, 0 to remove and 179 not upgraded.
Need to get 7,470 kB of archives.
After this operation, 36.4 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://cn.archive.ubuntu.com/ubuntu hirsute/main amd64 vim-runtime all 2:8.2.2434-1ubuntu1 [6,083 kB]
Get:2 http://cn.archive.ubuntu.com/ubuntu hirsute/main amd64 vim amd64 2:8.2.2434-1ubuntu1 [1,387 kB]                                                    
Fetched 7,470 kB in 48s (154 kB/s)                                                                                                                       
Selecting previously unselected package vim-runtime.
(Reading database ... 189666 files and directories currently installed.)
Preparing to unpack .../vim-runtime_2%3a8.2.2434-1ubuntu1_all.deb ...
Adding 'diversion of /usr/share/vim/vim82/doc/help.txt to /usr/share/vim/vim82/doc/help.txt.vim-tiny by vim-runtime'
Adding 'diversion of /usr/share/vim/vim82/doc/tags to /usr/share/vim/vim82/doc/tags.vim-tiny by vim-runtime'
Unpacking vim-runtime (2:8.2.2434-1ubuntu1) ...
Selecting previously unselected package vim.
Preparing to unpack .../vim_2%3a8.2.2434-1ubuntu1_amd64.deb ...
Unpacking vim (2:8.2.2434-1ubuntu1) ...
Setting up vim-runtime (2:8.2.2434-1ubuntu1) ...
Setting up vim (2:8.2.2434-1ubuntu1) ...
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/vim (vim) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/vimdiff (vimdiff) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/rvim (rvim) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/rview (rview) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/vi (vi) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/view (view) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/ex (ex) in auto mode
Processing triggers for man-db (2.9.4-2) ...
ubuntu@ubuntu:~$ vim
ubuntu@ubuntu:~$ dpkg -l | grep -i vim
ii  vim                                        2:8.2.2434-1ubuntu1                                                  amd64        Vi IMproved - enhanced vi editor
ii  vim-common                                 2:8.2.2434-1ubuntu1                                                  all          Vi IMproved - Common files
ii  vim-runtime                                2:8.2.2434-1ubuntu1                                                  all          Vi IMproved - Runtime files
ii  vim-tiny                                   2:8.2.2434-1ubuntu1                                                  amd64        Vi IMproved - enhanced vi editor - compact version
ubuntu@ubuntu:~$ 

root账号密码初始化

Ubuntu安装好后，root初始密码随机，需要设置。

1. sudo passwd：修改密码

ubuntu@ubuntu:~$ sudo passwd
[sudo] password for ubuntu: 
New password: 

2. su - root：切换用户尝试

ubuntu@ubuntu:~$ su - root
Password: 
root@ubuntu:~# exit
logout
ubuntu@ubuntu:~$ 

root密码修改后能通过安装时候的用户切换到root用户，但无法通过ssh直接使用root连接

3. 允许root用户登录，编辑sshd_config

找到Authentication项下的PermitRootLogin prohibit-password改成PermitRootLogin yes

ubuntu@ubuntu:~$ sudo vim /etc/ssh/sshd_config
ubuntu@ubuntu:~$ 

4. 重启sshd

ubuntu@ubuntu:~$ systemctl restart sshd
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to restart 'ssh.service'.
Authenticating as: ubuntu,,, (ubuntu)
Password: 
==== AUTHENTICATION COMPLETE ===
ubuntu@ubuntu:~$ 

修改hostname

1. 切换root账号

ubuntu@ubuntu:~$ su - root
Password: 
root@ubuntu:~# 

2.修改/etc/hostname

root@ubuntu:~# vim /etc/hostname 

3.重启服务器

root@ubuntu:~# reboot

5. ssh连接测试

简单防火墙查看ufw

官方介绍：https://help.ubuntu.com/community/UFW#UFW
ptables
iptables是防火墙规则的数据库，是 Linux 系统中实际使用的防火墙。Linux系统中配置iptables的传统界面是命令行界面终端。本节中的其他实用程序简化了 iptables 数据库的操作。
UFW
UFW（Uncomplicated Firewall）是 iptables 的前端，特别适合基于主机的防火墙。UFW 是专门为 Ubuntu 开发的（但在其他发行版中可用），并且也是从终端配置的。
Gufw是 UFW 的图形前端，推荐给初学者。
UFW 是在 Ubuntu 8.04 LTS (Hardy Heron) 中引入的，并且在 8.04 LTS 之后的所有 Ubuntu 安装中默认可用。

查看防火墙状态

ubuntu@ubuntu:~$ sudo ufw status
Status: inactive
ubuntu@ubuntu:~$ 

启用防火墙

ubuntu@ubuntu:~$ sudo ufw enable
Command may disrupt existing ssh connections. Proceed with operation (y|n)? y
Firewall is active and enabled on system startup
ubuntu@ubuntu:~$ sudo ufw status
Status: active
ubuntu@ubuntu:~$ sudo ufw status
Status: active
ubuntu@ubuntu:~$ sudo ufw status verbose
Status: active
Logging: on (low)
Default: deny (incoming), allow (outgoing), disabled (routed)
New profiles: skip
ubuntu@ubuntu:~$ 

关闭防火墙

ubuntu@ubuntu:~$ sudo ufw disable
Firewall stopped and disabled on system startup
ubuntu@ubuntu:~$ sudo ufw status
Status: inactive
ubuntu@ubuntu:~$ 

防火墙日志的开放/关闭

sudo ufw logging on
sudo ufw logging off

开放端口

sudo ufw allow <port>/<optional: protocol>

拒绝端口

sudo ufw deny <port>/<optional: protocol>

开放端口(高级应用)

sudo ufw allow <port>/<optional: protocol>

sudo ufw allow 22

Allow by Specific IP

sudo ufw allow from <ip address>

sudo ufw allow from 192.168.0.1

Allow by Subnet

sudo ufw allow from 192.168.1.0/24

Allow by specific port and IP address

sudo ufw allow from <target> to <destination> port <port number>

sudo ufw allow from 192.168.0.4 to any port 22

Allow by specific port, IP address and protocol

sudo ufw allow from <target> to <destination> port <port number> proto <protocol name>

sudo ufw allow from 192.168.0.4 to any port 22 proto tcp

拒绝端口(高级应用)

sudo ufw deny <port>/<optional: protocol>

sudo ufw deny  22

Deny by specific IP

sudo ufw deny from <ip address>

Deny by specific port and IP address

sudo ufw deny from <ip address> to <protocol> port <port number>

sudo ufw deny from 192.168.0.1 to any port 22

删除存在的规则

sudo ufw delete deny 80/tcp

使用编号规则

查看编号规则

sudo ufw status numbered

删除编号规则

sudo ufw delete 1

新增编号规则

sudo ufw insert 1 allow from <ip address>