問題：
對於通過代理訪問內網服務器，我們需要通過http代理訪問代理服務器，再訪問內網服務器。而mac不支持xshell從而無法爲SSH連接增加代理，所以選擇corkscrew工具。
解決步驟：
1、通過Homebrew包管理工具（Homebrew的安裝和使用見鏈接）安裝corscrew
brew install corkscew
# 無需sudo
2、修改~/.ssh/config 配置文件（沒有則添加該文件）
1、How Is It Used?
---------------
#Setting up Corkscrew with SSH/OpenSSH is very simple. Adding
#the following line to your ~/.ssh/config file will usually do
#the trick (replace proxy.example.com and 8080 with correct values):
ProxyCommand /usr/local/bin/corkscrew proxy.example.com 8080 %h %p
2、How Do I Use The HTTP Authentication Feature?
---------------------------------------------
#You will need to create a file that contains your usename and password
#in the form of :
username:password
#I suggest you place this file in your ~/.ssh directory.
#After creating this file you will need to ensure that the proper perms
#are set so nobody else can get your username and password by reading
#this file. So do this :
chmod 600 myauth
#Now you will have to change the ProxyCommand line in your ~/.ssh/config
#file. Here's an example :
ProxyCommand /usr/local/bin/corkscrew proxy.work.com 80 %h %p ~/.ssh/myauth
3、重啓ssh服務（mac沒有service指令，使用如下指令）
# 啓動ssh服務（Mac默認情況下不會開機自啓ssh服務）
sudo launchctl load -w /System/Library/LaunchDaemons/ssh.plist
# 查看ssh服務狀態，出現 “- 0 com.openssh.sshd” 則啓動成功
sudo launchctl list | grep ssh
# 關閉ssh服務
sudo launchctl unload -w /System/Library/LaunchDaemons/ssh.plist
4、最後使用SSH命令連接目標服務器即可
sudo ssh <username>@<serverIP>
# username爲連接服務器的用戶名，serverIP爲請求連接的服務器內網IP地址
