ssh connection through proxy

30 June 2020

最近经常在Azure Global上的Ubuntu下工作。无奈，在中国访问Azure国际云速度是相当的慢。好在有国际代理，那么问题来了，如何通过代理 ssh 远程登录Ubuntu呢？

方法是这样的：

alias ubuntu='ssh -i ~/.ssh/id_rsa km@kimi.im -o "ProxyCommand=nc -X connect -x 127.0.0.1:1080 %h %p"'

以上这个 alias 就可以通过本地1080端口的代理访问远程服务器 kimi.im ，用户名为 km 。

不过，如果你没有装 nc 的话，敲了 ubuntu 命令时候，会提示说找不到 nc ， Cygwin 环境用 apg-cyg 安装 nc ：

$ apt-cyg install nc
Installing nc
--2020-06-30 20:47:40--  https://mirrors.tuna.tsinghua.edu.cn/cygwin//x86_64/release/nc/nc-1.107-4.tar.bz2
Resolving mirrors.tuna.tsinghua.edu.cn (mirrors.tuna.tsinghua.edu.cn)... 101.6.8.193, 2402:f000:1:408:8100::1
Connecting to mirrors.tuna.tsinghua.edu.cn (mirrors.tuna.tsinghua.edu.cn)|101.6.8.193|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 17895 (17K) [application/octet-stream]
Saving to: ‘nc-1.107-4.tar.bz2’

nc-1.107-4.tar.bz2  100%[===================>]  17.48K  --.-KB/s    in 0s

2020-06-30 20:47:41 (36.0 MB/s) - ‘nc-1.107-4.tar.bz2’ saved [17895/17895]

nc-1.107-4.tar.bz2: OK
Unpacking...
Package nc requires the following packages, installing:
cygwin
Package cygwin is already installed, skipping
Package nc installed

另外，我还在远程运行 clojure 的 nrel ，通过 Emacs cider 连接，所以还要把代理加到 cider 的远程连接上：

(defun nrepl--ssh-tunnel-command (ssh dir port)
  "Command string to open SSH tunnel to the host associated with DIR's PORT."
  (with-parsed-tramp-file-name dir v
    ;; this abuses the -v option for ssh to get output when the port
    ;; forwarding is set up, which is used to synchronise on, so that
    ;; the port forwarding is up when we try to connect.
    (format-spec
     "%s -v -N -L %p:localhost:%p %u'%h' %x"
     `((?s . ,ssh)
       (?p . ,port)
       (?h . ,v-host)
       (?u . ,(if v-user (format "-l '%s' " v-user) ""))
       (?x . "-o \"ProxyCommand=nc -X connect -x 127.0.0.1:1080 %h %p\"")))))

好了，这样 ssh 和 cider 都可以快速访问Azure了。

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