挑戰使用下面指令, 重新跟 DHCP 要 IP還是無解:

dhclient ens3

由於 ip v4 沒有功能, 造成 telent 指令會傳回錯誤訊息:

Unable to connect to remote host: Network is unreachable

由於沒有網路可以使用, 這台VM 變成直接使用 console 的方式去控制, 伺服器裡的資料也帶不出來。

服用下面指令, 就可以手動地, 把ipv4 加入 ens3

sudo ip addr add 192.168.211.17/16 dev ens3
sudo ip link set dev ens3 up
sudo ip link set dev ens3 down

資料來源: Configuring networks
https://ubuntu.com/server/docs/network-configuration

說明：ens3 是網卡名，可能會是eth0

up 是啟用。

down 會被停用。

Execute Command Using SSH

Run / Execute Command SSH Command Syntax

The syntax is as follows for executing commands over ssh:

ssh user1@server1 command1
ssh user1@server1 'command2'

# pipe #
ssh user1@server1 'command1 | command2'

# multiple commands, must enclose in quotes
ssh admin@box1 "command1; command2; command3"

Copy Files From Remote to Local

有 ip address 之後, 就可以使用 scp 指令, 把伺服器裡的檔案 copy 出來:

A better way to understand this is by use of an example. Take a scenario where you want to copy files from remote system. To copy the files you will need to first invoke the SCP, followed by the remote username@IP address, path to file.

If you do not specify the path, it is assumed as default in this case which will be the user’s home directory, this will be followed the path where the file will be stored locally.

The Syntax

scp <remote_username>@<IPorHost>:<PathToFile>   <LocalFileLocation>

I wanted to copy a file named remote-path from the remote device with this address 192.168.211.17.

scp remote-account@192.168.211.17:remote-path .

scp 指令語法:

usage: scp [-346ABCOpqRrsTv] [-c cipher] [-D sftp_server_path] [-F ssh_config]
[-i identity_file] [-J destination] [-l limit]
[-o ssh_option] [-P port] [-S program] source … target

比較常用的應該只有大寫P 的 port 參數.

Copy File From Local Host to Remote Server

如果是要推檔案出去別台電腦：

scp -P port file remote-account@destination:/remote-path

EX:

scp *.zip user@destination_host:/home/max/

滿方便的，可以自動 overwrite exist file.

Execute remote command

用單引號或雙引號即可

ssh user1@server1 'command2'

# pipe
$ ssh user1@server1 'command1 | command2'

# multiple commands
$ ssh user1@server1 "command1; command2; command3"

To execute multiple commands, each command needs to be separated using a semicolon(;) to be enclosed within a single quote or double quote,

Add backup user account

在 ubuntu add user:

sudo adduser newuser

設定帳號密碼

sudo passwd newuser

檢查groups

groups newuser

ubuntu 加入為管理者:

sudo usermod -aG sudo newuser

rocky 加入為管理者:

sudo usermod -aG wheel newuser

切換目前的使用者帳號:

sudo su - newuser

建立 SSH 金鑰, 指令用法：

usage: ssh-keygen [-q] [-b bits] [-t dsa | ecdsa | ed25519 | rsa] [-m format]
          [-N new_passphrase] [-C comment] [-f output_keyfile]
ssh-keygen -p [-P old_passphrase] [-N new_passphrase] [-m format]
           [-f keyfile]
ssh-keygen -i [-m key_format] [-f input_keyfile]
ssh-keygen -e [-m key_format] [-f input_keyfile]
ssh-keygen -y [-f input_keyfile]
ssh-keygen -c [-P passphrase] [-C comment] [-f keyfile]
ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile]
ssh-keygen -B [-f input_keyfile]
ssh-keygen -D pkcs11
ssh-keygen -F hostname [-f known_hosts_file] [-l]
ssh-keygen -H [-f known_hosts_file]
ssh-keygen -R hostname [-f known_hosts_file]
ssh-keygen -r hostname [-f input_keyfile] [-g]
ssh-keygen -G output_file [-v] [-b bits] [-M memory] [-S start_point]
ssh-keygen -T output_file -f input_file [-v] [-a rounds] [-J num_lines]
          [-j start_line] [-K checkpt] [-W generator]
ssh-keygen -s ca_key -I certificate_identity [-h] [-U]
          [-D pkcs11_provider] [-n principals] [-O option]
          [-V validity_interval] [-z serial_number] file ...
ssh-keygen -L [-f input_keyfile]
ssh-keygen -A
ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number]
          file ...
ssh-keygen -Q -f krl_file file ...

指令範例:

ssh-keygen -t ed25519

說明: 參數 [-t dsa | ecdsa | ed25519 | rsa], 有4種加密方式。

檢查 authorized_keys , 確認公鑰已經在裡面：

cat ~/.ssh/authorized_keys

要切換 ssh 是密碼格式, 還是用key, 修改 /etc/ssh/sshd_config 檔案。

sudo vim /etc/ssh/sshd_config

把 PasswordAuthentication 的 no 改成 yes。

/etc/ssh/sshd_config 檔案裡可以設定那些帳號才可以登入:

AllowUsers user1 user2

再重啟 sshd service:

service sshd restart

詳細的 ssh 操作流程, 請參考:
How To Configure SSH Key-Based Authentication on a Linux Server
https://www.digitalocean.com/community/tutorials/how-to-configure-ssh-key-based-authentication-on-a-linux-server

ssh 指令用法:

usage: ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface]
           [-b bind_address] [-c cipher_spec] [-D [bind_address:]port]
           [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11]
           [-i identity_file] [-J [user@]host[:port]] [-L address]
           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]
           [-Q query_option] [-R address] [-S ctl_path] [-W host:port]
           [-w local_tun[:remote_tun]] destination [command [argument ...]]

Rocky Linux

這個問題，不只在Ubuntu Linux 在Rocky Linux 也會遇到：

一樣，是少了 inet4

使用指令：

dhclient eth0

結果：畫面會卡住。只能按Ctrl+C 中斷。

使用

sudo ip addr add 192.168.211.17/16 dev eth0
sudo ip link set dev eth0 up

測試結果無效…，網路回不來。

建議，有重要的檔案，最好設定排程，定時地備份到別台電腦，避免這個網卡掛掉，資料拿不出來。

Error:
 Problem: package kernel-4.18.0-425.13.1.el8_7.x86_64 requires kernel-core-uname-r = 4.18.0-425.13.1.el8_7.x86_64, but none of the providers can be installed
  - conflicting requests

執行畫面

說明

增加使用 --refresh --nobest --skip-broken 參數, 一樣錯誤.

解法

先使用指令

rpm -qa kernel* | sort

列出系統目前使用的 kernal 有那些.

再使用指令

dnf remove kernel-....

把你有問題的 kernal 從系統移除, 這時候, 再用 dnf update 就可以成功地不顯示錯誤訊息.

執行畫面

資料來源

Cannot update Fedora due to kernel error
https://discussion.fedoraproject.org/t/cannot-update-fedora-due-to-kernel-error/78706/8?replies_to_post_number=7

取得下載連結後，到主機上執行 wget 指令，下載到 Downloads folder.

cd Downloads
wget (這裡是你的 eclipse 下載連結)
tar -xvf eclipse-jee-2022-12-R-linux-gtk-x86_64.tar.gz

你的 eclipse 壓縮檔的檔名，可能會與我不同。

解開 tar.gz 檔後，就會看到 ellipse 資料夾，點2點，就有 eclipse 可以使用了。

先用 sudo dnf list 或用指令：sudo dnf search python 可以看到，預設最多只有到 python3.9, 要升到 3.10 或 3.11 就要下比較多指令

先使用

sudo dnf install python39

或

sudo yum install python39

按下Y 之後，應該會取到目前 python 3.9 的最後一版 3.9.13

Installed:
  python39-3.9.13-2.module+el8.7.0+1092+55aa9635.x86_64                         
  python39-libs-3.9.13-2.module+el8.7.0+1092+55aa9635.x86_64                    
  python39-pip-20.2.4-7.module+el8.7.0+1064+ad564229.noarch                     
  python39-pip-wheel-20.2.4-7.module+el8.7.0+1064+ad564229.noarch               
  python39-setuptools-50.3.2-4.module+el8.5.0+673+10283621.noarch               
  python39-setuptools-wheel-50.3.2-4.module+el8.5.0+673+10283621.noarch         

Complete!

使用下面的指令來升級：

sudo dnf update -y
sudo dnf install curl gcc openssl-devel bzip2-devel libffi-devel zlib-devel wget make -y
wget https://www.python.org/ftp/python/3.10.0/Python-3.10.0.tar.xz
tar -xf Python-3.10.0.tar.xz
cd Python-3.10.0
./configure --enable-optimizations
make -j 2
nproc
make altinstall

在這個資料夾下指令：

python3.10 --version

應就會會看到：

Python 3.10.0

雖然升級上去了，但還是遇到很多問題，像是 tkinter, 還要另外針對 python3.9 做安裝。@_@；

Fedora 的Linux平台使用查詢指令

sudo dnf list python3*

可以看到每一個python版本都有自帶的 tkinter 套件, 如果想安裝 python 3.8 版的 tkinter, 請下指令:

sudo dnf install python38-tkinter

想安裝 python 3.8 版的 tkinter

sudo dnf install python39-tkinter

如果是 ubuntu 平台安裝 tkinter:

sudo apt install python3-tk

On CentOS, RedHat, and Oracle Linux systems:

sudo yum install -y tkinter tk-devel

多個python3 版本, 使用 python3 指令時, 要使用那一個版本?

請使用指令來指派預設的 python3 版本,

Debian / Ubuntu:

sudo update-alternatives --config python3

CentOS / Rocky:

sudo alternatives --config python3

Download GPG key:

sudo dnf install wget -y

輸出的訊息：

$ sudo dnf install wget -y
[sudo] password for max: 
Sorry, try again.
[sudo] password for max: 
Rocky Linux 8 - AppStream                       5.3 kB/s | 4.8 kB     00:00    
Rocky Linux 8 - BaseOS                          7.7 kB/s | 4.3 kB     00:00    
Rocky Linux 8 - Extras                          4.8 kB/s | 3.1 kB     00:00    
Extra Packages for Enterprise Linux 8 - x86_64  8.0 kB/s | 8.7 kB     00:01    
Extra Packages for Enterprise Linux 8 - x86_64  1.7 MB/s |  14 MB     00:08    
Package wget-1.19.5-10.el8.x86_64 is already installed.
Dependencies resolved.
Nothing to do.
Complete!

wget https://dl.google.com/linux/linux_signing_key.pub

輸出訊息：

$ wget https://dl.google.com/linux/linux_signing_key.pub
--2023-02-27 13:58:36--  https://dl.google.com/linux/linux_signing_key.pub
Resolving dl.google.com (dl.google.com)... 172.217.163.46, 2404:6800:4012:4::200e
Connecting to dl.google.com (dl.google.com)|172.217.163.46|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 14613 (14K) [application/octet-stream]
Saving to: 'linux_signing_key.pub'

linux_signing_key.p 100%[===================>]  14.27K  --.-KB/s    in 0s      

2023-02-27 13:58:37 (66.5 MB/s) - 'linux_signing_key.pub' saved [14613/14613]

sudo rpm --import linux_signing_key.pub
wget https://dl.google.com/linux/direct/google-chrome-stable_current_x86_64.rpm

輸出訊息：

--2023-02-27 14:01:34--  https://dl.google.com/linux/direct/google-chrome-stable_current_x86_64.rpm
Resolving dl.google.com (dl.google.com)... 172.217.163.46, 2404:6800:4012:4::200e
Connecting to dl.google.com (dl.google.com)|172.217.163.46|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 100101712 (95M) [application/x-rpm]
Saving to: 'google-chrome-stable_current_x86_64.rpm'

google-chrome-stabl 100%[===================>]  95.46M   120MB/s    in 0.8s    

2023-02-27 14:01:35 (120 MB/s) - 'google-chrome-stable_current_x86_64.rpm' saved [100101712/100101712]

sudo dnf install google-chrome-stable_current_x86_64.rpm

輸出訊息：

Last metadata expiration check: 0:09:44 ago on Mon 27 Feb 2023 01:52:57 PM CST.
Dependencies resolved.
================================================================================
 Package                   Arch      Version              Repository       Size
================================================================================
Installing:
 google-chrome-stable      x86_64    110.0.5481.177-1     @commandline     95 M
Installing dependencies:
 liberation-fonts          noarch    1:2.00.3-7.el8       baseos           19 k
 liberation-sans-fonts     noarch    1:2.00.3-7.el8       baseos          609 k
 liberation-serif-fonts    noarch    1:2.00.3-7.el8       baseos          608 k
 mesa-vulkan-drivers       x86_64    22.1.5-2.el8         appstream       5.9 M
 vulkan-loader             x86_64    1.3.224.0-2.el8      appstream       138 k

Transaction Summary
================================================================================
Install  6 Packages

Total size: 103 M
Total download size: 7.3 M
Installed size: 329 M
Is this ok [y/N]:

這時候，要輸入 Y

然後就安裝好了～

Installed:
  google-chrome-stable-110.0.5481.177-1.x86_64                                  
  liberation-fonts-1:2.00.3-7.el8.noarch                                        
  liberation-sans-fonts-1:2.00.3-7.el8.noarch                                   
  liberation-serif-fonts-1:2.00.3-7.el8.noarch                                  
  mesa-vulkan-drivers-22.1.5-2.el8.x86_64                                       
  vulkan-loader-1.3.224.0-2.el8.x86_64                                          

Complete!

檢查 repo 有無進系統環境中

sudo dnf repolist

執行結果：

可以看到 google-chrome 就是正確了。