服务器评测
隧道 被设计用于远端客户端和本地(可通过inetd启动)或远端服务器间的SSL加密封装。它可以用于为inetd进程增加SSL功能，像POP2（译注：厄，POP2这个服务还有人用么？），POP3和IMAP服务而不必改变程序代码。隧道使用OpenSSL库用于加密，因此它支持任何被编译进库的加密算法。简而言之，隧道可以使任何一个不安全的端口变得安全加密。
在本篇中，我会描述如何通过SSL水稻封装SSH。这个步骤非常简单。你需要在你的客户端PC和远程PC都已经安装运行了sshd。
我正在使用下面提到的两个系统。
远程系统:
操作系统: Debian 7 IP 地址: 192.168.1.200/24
客户端(本地) 系统:
操作系统: Ubuntu 13.04 desktop IP 地址: 192.168.1.100/24
配置远程系统
让我们在远程Debian 7服务器上安装stunnel包。
# apt-get install stunnel4
现在让我们像下面那样创建一个SSL证书。
# openssl genrsa 1024 > stunnel.key
示例输出:
Generating RSA private key, 1024 bit long modulus ............................................++++++ ...................++++++ e is 65537 (0x10001) # openssl req -new -key stunnel.key -x509 -days 1000 -out stunnel.crt
你会被询问若干个问题如国家、州、公司细节等。
You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]:IN State or Province Name (full name) [Some-State]:Tamilnadu Locality Name (eg, city) []:Erode Organization Name (eg, company) [Internet Widgits Pty Ltd]:unixmen Organizational Unit Name (eg, section) []:Technical Common Name (e.g. server FQDN or YOUR name) []:server.unixmen.com Email Address []:sk@unixmen.com # cat stunnel.crt stunnel.key > stunnel.pem # mv stunnel.pem /etc/stunnel/
现在我们需要配置stunnel来将 443(https)隧道到22(ssh)。这可以通过在/etc/stunnel/目录下创建stunnel.conf文件来实现：
# vi /etc/stunnel/stunnel.conf
并加入下面的行:
pid = /var/run/stunnel.pid cert = /etc/stunnel/stunnel.pem [ssh] accept = 192.168.1.200:443 connect = 127.0.0.1:22
上面的几行说明了stunnel在哪里寻找证书文件和哪里接收和转发ssh链接。在本例中，stunnel会接收来自443端口的流量并会转发给22端口。
保存并关闭文件。
现在让我们启用stunnel服务。要这么做，编辑文件 /etc/default/stunnel4:
# vi /etc/default/stunnel4
改变行从 ENABLED = 0 到 1。
# /etc/default/stunnel # Julien LEMOINE <speedblue@debian.org> # September 2003 # Change to one to enable stunnel automatic startup ENABLED=1 FILES="/etc/stunnel/*.conf" OPTIONS="" # Change to one to enable ppp restart scripts PPP_RESTART=0
接着使用命令启用stunnel服务:
# service stunnel4 start
更多Ubuntu相关信息见Ubuntu 专题页面 http://www.linuxidc.com/topicnews.aspx?tid=2
相关阅读：
Ubuntu 下配置 SSH服务全过程及问题解决 http://www.linuxidc.com/Linux/2011-09/42775.htm
Ubuntu 12.04下安装Git,SSH及出现的Permission denied解决办法 http://www.linuxidc.com/Linux/2013-06/85336.htm
Ubuntu 12.10下OpenSSH的离线安装方法 http://www.linuxidc.com/Linux/2013-04/82814.htm
Ubuntu下SSH安装或设置 http://www.linuxidc.com/Linux/2013-07/87368.htm
配置本地系统
用这个命令安装stunnel:
$ sudo apt-get install stunnel4
我们需要远程系统上相同的证书文件(stunnel.pem)。复制远程系统上的 stunnel.pem文件到我们本地系统中并在相同的位置保存(也就是 /etc/stunnel)。
在 /etc/stunnel/目录下创建新的文件stunnel.conf：
$ sudo vi /etc/stunnel/stunnel.conf
加入下面的行:
pid = /var/run/stunnel.pid cert = /etc/stunnel/stunnel.pem client=yes [ssh] accept=443 connect=192.168.1.200:443
保存并关闭文件。这里的192.168.1.200是我们的远程系统IP。
现在让我们启用stunnel服务。要这么做，编辑文件/etc/default/stunnel4:
$ sudo vi /etc/default/stunnel4
改变行从 ENABLED = 0 到 1.
# /etc/default/stunnel # Julien LEMOINE <speedblue@debian.org> # September 2003 # Change to one to enable stunnel automatic startup ENABLED=1 FILES="/etc/stunnel/*.conf" OPTIONS="" # Change to one to enable ppp restart scripts PPP_RESTART=0
接着使用命令启用stunnel服务:
$ sudo service stunnel4 start
测试SSH连接
现在这样已经很好了，你可以使用命令连接到你的远程机器上了：
$ ssh sk@localhost -v -p 443
示例输出:
OpenSSH_6.1p1 Debian-4, OpenSSL 1.0.1c 10 May 2012 debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 19: Applying options for * debug1: Connecting to localhost [127.0.0.1] port 443. debug1: Connection established. debug1: identity file /home/sk/.ssh/id_rsa type -1 debug1: identity file /home/sk/.ssh/id_rsa-cert type -1 debug1: identity file /home/sk/.ssh/id_dsa type -1 debug1: identity file /home/sk/.ssh/id_dsa-cert type -1 debug1: identity file /home/sk/.ssh/id_ecdsa type -1 debug1: identity file /home/sk/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_6.0p1 Debian-4 debug1: match: OpenSSH_6.0p1 Debian-4 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_6.1p1 Debian-4 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr hmac-md5 none debug1: sending SSH2_MSG_KEX_ECDH_INIT debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ECDSA 78:05:ba:1b:73:02:75:86:10:33:8c:0f:21:61:d4:de debug1: Host '[localhost]:443' is known and matches the ECDSA host key. debug1: Found key in /home/sk/.ssh/known_hosts:12 debug1: ssh_ecdsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,password debug1: Next authentication method: publickey debug1: Trying private key: /home/sk/.ssh/id_rsa debug1: Trying private key: /home/sk/.ssh/id_dsa debug1: Trying private key: /home/sk/.ssh/id_ecdsa debug1: Next authentication method: password sk@localhost's password: # ## Enter your remote system user password debug1: Authentication succeeded (password). Authenticated to localhost ([127.0.0.1]:443). debug1: channel 0: new [client-session] debug1: Requesting no-more-sessions@openssh.com debug1: Entering interactive session. debug1: Sending environment. debug1: Sending env LC_PAPER = en_IN.UTF-8 debug1: Sending env LC_ADDRESS = en_IN.UTF-8 debug1: Sending env LC_MONETARY = en_IN.UTF-8 debug1: Sending env LC_NUMERIC = en_IN.UTF-8 debug1: Sending env LC_TELEPHONE = en_IN.UTF-8 debug1: Sending env LC_IDENTIFICATION = en_IN.UTF-8 debug1: Sending env LANG = en_US.UTF-8 debug1: Sending env LC_MEASUREMENT = en_IN.UTF-8 debug1: Sending env LC_TIME = en_IN.UTF-8 debug1: Sending env LC_NAME = en_IN.UTF-8 Linux server 3.2.0-4-486 #1 Debian 3.2.51-1 i686 The programs included with the Debian GNU/Linux system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. You have new mail. Last login: Mon Dec 30 15:12:22 2013 from localhost sk@server:~$
或者你可以简单地使用下面的命令:
$ ssh -p 443 sk@localhost
示例输出:
sk@localhost's password: Linux server 3.2.0-4-486 #1 Debian 3.2.51-1 i686 The programs included with the Debian GNU/Linux system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. You have new mail. Last login: Mon Dec 30 15:22:08 2013 from localhost sk@server:~$
现在你可以用ssh连接到你的远程机器上了，但是所有的流量通过SSL隧道。
你已经完成了！即使ssh的默认端口被防火墙阻止了，你仍然可以使用SSH到你的远程系统。
参考链接:
- stunnel 主页
