通过代理连接 SSH

If your SSH proxy connection is going to be used often, you don't have to pass them as parameters each time. you can add the following lines to ~/.ssh/config

Host foobar.example.com
ProxyCommand          nc -X connect -x proxyhost:proxyport %h %p
ServerAliveInterval   10

then to connect use

ssh foobar.example.com

Source here

Here's how to do Richard Christensen's answer as a one-liner, no file editing required (replace capitalized with your own settings, PROXYPORT is frequently 80):

 ssh USER@FINAL_DEST -o "ProxyCommand=nc -X connect -x PROXYHOST:PROXYPORT %h %p"

You can use the same -o ... option for scp as well, see my superuser answer.

If you get this in OS X:

 nc: invalid option -- X
Try `nc --help' for more information.

it may be that you're accidentally using the homebrew version of netcat (you can see by doing a which -a nc command--/usr/bin/nc should be listed first). If there are two then one workaround is to specify the full path to the nc you want, like ProxyCommand=/usr/bin/nc ...

For CentOS nc has the same problem of invalid option --X. connect-proxy is an alternative, easy to install using yum and works --

ssh -o ProxyCommand="connect-proxy -S PROXYHOST:PROXYPORT %h %p" USER@FINAL_DEST

I use -o "ProxyCommand=nc -X 5 -x proxyhost:proxyport %h %p" ssh option to connect through socks5 proxy on OSX.

Just a remark to @rogerdpack's answer: for windows platform it is really hard to find a nc.exe with -X(http_proxy), however, I have found nc can be replaced by ncat, full example as follows:

Host github.com
HostName github.com
#ProxyCommand nc -X connect -x 127.0.0.1:1080 %h %p
ProxyCommand ncat --proxy 127.0.0.1:1080 %h %p
User git
Port 22
IdentityFile D:\Users\Administrator\.ssh\github_key

and ncat with --proxy can work perfectly.

$ which nc
/bin/nc


$ rpm -qf /bin/nc
nmap-ncat-7.40-7.fc26.x86_64


$ ssh -o "ProxyCommand nc --proxy <addr[:port]> %h %p" USER@HOST


$ ssh -o "ProxyCommand nc --proxy <addr[:port]> --proxy-type <type> --proxy-auth <auth> %h %p" USER@HOST

In my case since I had a jump host or Bastion host on the way, and because the signatures on these bastion nodes had changed since they were imported into known_hosts file, I just needed to delete those entries/lines from the following file:

/Users/a.abdi-kelishami/.ssh/known_hosts

From above file, delete those lines referring to the bastion hosts.

I was using the following lines in my .ssh/config (which can be replaced by suitable command line parameters) under Ubuntu

Host remhost
HostName      my.host.com
User          myuser
ProxyCommand  nc -v -X 5 -x proxy-ip:1080 %h %p 2> ssh-err.log
ServerAliveInterval 30
ForwardX11 yes

When using it with Msys2, after installing gnu-netcat, file ssh-err.log showed that option -X does not exist. nc --help confirmed that, and seemed to show that there is no alternative option to handle proxies.

So I installed openbsd-netcat (pacman removed gnu-netcat after asking, since it conflicted with openbsd-netcat). On a first view, and checking the respective man pages, openbsd-netcat and Ubuntu netcat seem to very similar, in particular regarding options -X and -x. With this, I connected with no problems.

ProxyCommand nc -proxy xxx.com:8080 %h %p

remove -X connect and use -proxy instead.

Worked for me.

For windows, @shoaly parameters didn't completely work for me. I was getting this error:

NCAT DEBUG: Proxy returned status code 501.
Ncat: Proxy returned status code 501.
ssh_exchange_identification: Connection closed by remote host

I wanted to ssh to a REMOTESERVER and the SSH port had been closed in my network. I found two solutions but the second is better.

• To solve the problem using Ncat:

  1. I downloaded Tor Browser, run and wait to connect.
  2. I got Ncat from Nmap distribution and extracted ncat.exe into the current directory.

  3. SSH using Ncat as ProxyCommand in Git Bash with addition --proxy-type socks4 parameter:

     ssh -o "ProxyCommand=./ncat --proxy-type socks4 --proxy 127.0.0.1:9150 %h %p" USERNAME@REMOTESERVER
     

     Note that this implementation of Ncat does not support socks5.

• THE BETTER SOLUTION:

  1. Do the previous step 1.

  2. SSH using connect.c as ProxyCommand in Git Bash:

     ssh -o "ProxyCommand=connect -a none -S 127.0.0.1:9150 %h %p"
     

     Note that connect.c supports socks version 4/4a/5.

To use the proxy in git commands using ssh (for example while using GitHub) -- assuming you installed Git Bash in C:\Program Files\Git\ -- open ~/.ssh/config and add this entry:

host github.com
user git
hostname github.com
port 22
proxycommand "/c/Program Files/Git/mingw64/bin/connect.exe" -a none -S 127.0.0.1:9150 %h %p

I use proxychains ssh user@host; from proxychains-ng.
By default it uses a socks4 proxy at 127.0.0.1:9050 but it can be changed in the conf file /etc/proxychains.conf or you can specify another conf file like this: proxychains -f custom.conf

Try -o "ProxyCommand=nc --proxy HOST:PORT %h %p" for command in question. It worked on OEL6 but need to modify as mentioned for OEL7.

This is how I solved it, hoping to help others later.

My system is debian 10, and minimal installation.

I also have the same problem like this.

git clone git@github.com:nothing/nothing.git
Cloning into 'nothing'...
nc: invalid option -- 'x'
nc -h for help
ssh_exchange_identification: Connection closed by remote host
fatal: Could not read from remote repository.


Please make sure you have the correct access rights
and the repository exists.

Or

git clone git@github.com:nothing/nothing.git
Cloning into 'nothing'...
/usr/bin/nc: invalid option -- 'X'
nc -h for help
ssh_exchange_identification: Connection closed by remote host
fatal: Could not read from remote repository.


Please make sure you have the correct access rights
and the repository exists.

So, I know the nc has different versions like openbsd-netcat and GNU-netcat, you can change the nc in debian to the openbsd version, but I choose to change the software like corkscrew, because the names of the two versions of nc in system are same, and many people don’t understand it well. My approach is as follows.

sudo apt install corkscrew

Then.

vim ~/.ssh/config

Change this file like this.

Host github.com
User git
ProxyCommand corkscrew 192.168.1.22 8118 %h %p

192.168.1.22 and 8118 is my proxy server's address and port, you should change it according to your server address.

It's work fine.

Thanks @han.

If anybody on CentOS / RHEL get

nc: invalid option -- 'X'

use this ProxyCommand

ProxyCommand nc --proxy  HOST:PORT --proxy-type http %h %p

The easiest way to do this after OpenSSH 7.3 is with ProxyJump:

ssh USERNAME@HOSTNAME -J PROXYHOSTNAME

which is short hand for the ProxyCommand below (which works on older clients):

ssh USERNAME@HOSTNAME -o "ProxyCommand=ssh PROXYHOSTNAME -W %h:%p"

Or in your ssh config file ($HOME/.ssh/config):

Host HOSTNAME
User USERNAME
ProxyCommand ssh PROXYHOSTNAME -W %h:%p

The oldest clients require the use of netcat. YMMV depending on the version of netcat and options supported (see other answers).