[CentOS] ssh port forwarding

Fri Jul 13 01:45:19 UTC 2012
SilverTip257 <silvertip257 at gmail.com>


It's also possible to send ssh to the background and also skip remote
commands (perfect for tunneling).

Options for ssh command:
-f  .......... background
-N ......... skip remote commands

** Personally I'd look for a more robust tunnel/VPN alternative. **
1) OpenSSH tun/tap devices - but this should really be used for a
'one-off' quick tunnel => requires root to establish, so it's not
ideal for every situation! (think roadwarriors, etc)
2) OpenVPN - SSL VPN - software/application based - simpler to set up
as a result
3) OpenSWAN - IPSec VPN - hooks into the kernel (netkey or klips)

//  SilverTip257  //

On Thu, Jul 12, 2012 at 4:15 PM, We Are Here <support at wearehere.net> wrote:
> At 19:15 12/07/2012, you wrote:
> Hi Doug,
>>Thanks for the feedback Tim.
> Glad I could help.
>>Using your string, I can now telnet to port 22222 on localhost (hostA) and
>>I get the mysql connection string (from hostB), but it is not able to make
>>a mysql connection (using mysql -u user -p -h localhost --port=22222 from
>>hostA), with a test user that I set up to allow connections from anywhere.
>>The error that I am getting is:
>>ERROR 2002 (HY000): Can't connect to local MySQL server through socket
>>'/var/lib/mysql/mysql.sock' (2)
>>I did test and the mysql test user that I created is able to connect from
> Because the mysql connection is via an ssh tunnel, you need to ensure
> on the MySQL server hostB
> that is allows the mysql user access from on hostB as that
> is effectively where the MySQL
> server on hostB sees the connection coming from.
>>Also, when I do this, it still opens up an ssh session, logging me into the
>>remote machine, thus making it so I can't use this terminal.
> Yes you need to run it is a screen session if you want it permanently
> connected.
>>The eventual goal is to do this in a script, that will open the connection,
>>use it for the duration of the script, and then close it when the script
>>finishes, but it looks like that won't work, since it is logging me into
>>the remote machine. I guess I could get around that by always leaving the
>>screen session going with the connection, but I would prefer only creating
>>the connection when I need it.
>>Any ideas how to do this without leaving the connection open all the time?
> I have used an expect script to do this in the past.  Which allows
> you to remotely log in to a server.
> Downside is you need to store the password in plain text in the
> expect script.  So make sure only
> root can read the script.  Or setup a lower privilege user to use
> sudo and do it that way.
> regards Tim
> Tim D'Cruz
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