====== ssh ======

http://www.aixchina.net/home/space.php?uid=73104&do=blog&id=30463

http://shenfeng.me/ssh-usage.html

Forward the local port 8080 to the remote server 8080,so you can visit the local server via the remote server.
  ssh -R :8080:localhost:8080 -Nf root@vps.pjq.me -p 2222
  
  
  
====== ssh auto login ======
  
  http://riny.net/2014/git-ssh-key/
  
===== ssh key generate =====
  Apps-iMac:.ssh pengjianqing$ ssh-keygen -t rsa -C "pengjianqing@gmail.com"
<code>
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/pengjianqing/.ssh/id_rsa): digitalocean_rsa
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in digitalocean_rsa.
Your public key has been saved in digitalocean_rsa.pub.
The key fingerprint is:
ec:aa:66:48:07:e0:91:53:73:2b:e9:14:c0:f6:ca:d5 pengjianqing@gmail.com
The key's randomart image is:
+--[ RSA 2048]----+
|..++ .           |
|.*  = .          |
|o.++..           |
| .+o.E .         |
|. oo    S        |
| o. .  .         |
| . o    .        |
|  . o  .         |
|   o...          |
+-----------------+
</code>

Then get the pub key
  cat digitalocean_rsa.pub

Add it to the server side
  root@pjq:~# vim ~/.ssh/authorized_keys
  
====== multiple ssh keys ======
Sometimes we will have many different ssh keys, so need config it to support different keys.
  
  touch ~/.ssh/config
Apps-iMac:.ssh pengjianqing$ cat config
<code>
Host ef.pjq.me
    IdentityFile ~/.ssh/digitalocean_rsa
    User root
</code>

so finally the config will be like this
<code>
Host ef.pjq.me
    IdentityFile ~/.ssh/digitalocean_rsa
    User root

Host aliyun.pjq.me
    IdentityFile ~/.ssh/aliyun_rsa
    User root

Host vps.pjq.me
    IdentityFile ~/.ssh/yardvps_rsa
    User root
</code>

  - Refer https://serverfault.com/questions/295768/how-do-i-connect-to-ssh-with-a-different-public-key
====== ssh socks 5 ======
  ssh -qTfnN -D 7070 root@vps.pjq.me -p 2222