ssh 連線

要設定懶惰 ssh 模式會牽涉到幾點
1. /etc/hosts (非必要)
2. ~/.ssh/config
3. 免密碼登入
以下分別說明



1. /etc/hosts
給 IP 一個別名(alias)，有點類似 domain name
必須用 sudo 才能編輯

user@localhost > sudo vim /etc/hosts
127.0.0.1<tab>localhost
127.0.1.1<tab>*********(hostname of computer)
IP_OF_TARGET_HOST<tab>MY_ALIAS # 加上這行
#當然也可以加很多行

# The following lines are desirable for IPv6 capable hosts
...

前後差異
[Before]
user@localhost > ssh USER_NAME@IP_OF_TARGET_HOST
[After]
user@localhost > ssh USER_NAME@MY_ALIAS


2. ~/.ssh/config
檔案原本不存在，要自己新創
Host: 給要連的主機一個暱稱，之後可以直接 ssh 這個暱稱
User: 連到 'Host' 那台主機的使用者名稱
HostName: 要連到的主機的 IP (也可搭配 /etc/hosts 內的 alias)

vim ~/.ssh/config
Host TARGET_HOST_NICKNAME
User USER_NAME
HostName IP_OF_TARGET_HOST # 若搭配 /etc/hosts 則可以直接用 MY_ALIAS
# 當然也可以有很多個設定

前後差異
[Before]
user@localhost > ssh USER_NAME@IP_OF_TARGET_HOST
[After]
user@localhost > ssh TARGET_HOST_NICKNAME


3. 免密碼登入
ssh-keygen
<輸入數個 enter>
之後把產生的 ~/.ssh/id_rsa.pub 複製到要連的主機上(假設複製到 ~/id_rsa.pub)
ssh 至要連的主機
將 public key 寫入 ~/.ssh/authorized_keys
* authorized_keys 權限必須設為 644 或 600 才行

user@localhost > ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/user/.ssh/id_rsa): <enter>
Enter passphrase (empty for no passphrase): <enter>
Enter same passphrase again: <enter>
Your identification has been saved in /home/user/.ssh/id_rsa.
Your public key has been saved in /home/user/.ssh/id_rsa.pub.
The key fingerprint is:
.......
The key's randomart image is:
.......
user@localhost > scp ~/.ssh/id_rsa.pub USER_NAME@IP_OF_TARGET_HOST:~/
USER_NAME@IP_OF_TARGET_HOST's password:
user@localhost > ssh USER_NAME@IP_OF_TARGET_HOST
USER_NAME@IP_OF_TARGET_HOST's password:
USER_NAME@TARGET_HOST > cat ~/id_rsa.pub >> ~/.ssh/authorized_keys

前後差異
[Before]
user@localhost > ssh  USER_NAME@IP_OF_TARGET_HOST
USER_NAME@IP_OF_TARGET_HOST's password:
USER_NAME@TARGET_HOST >
[After]
user@localhost > ssh  USER_NAME@IP_OF_TARGET_HOST
USER_NAME@TARGET_HOST >