Re: Help! My ISP blocks repo.or.cz. How to push changes? (a solution)

From: Asheesh Laroia <asheesh@asheesh.org>
Date: Jan 14, 2009, 17:18 UTC
Message-ID: <alpine.DEB.2.00.0901140913310.23681@vellum.laroia.net>
In-Reply-To: <200901141455.23935.jnareb@gmail.com>

On Wed, 14 Jan 2009, Jakub Narebski wrote:

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> Jakub Narebski wrote:
>
>> The ISP I use (Telekomunikacja Polska S.A., aka TP) made some
>> unannounced changes for ADSL service (Neostrada) which made it block
>> repo.or.cz (and of course its aliases, including git.or.cz where git
>> wiki resides).
>
> Thank you all for your help with arriving at solution. I'll describe it
> below; perhaps it would help somebody else (now that it is in mailing
> list archive).

I'll just add some comments that explain what I suggested with a little more clarity. I'm not saying you have to use it or anything, I just want to make sure I was clear!

And I'm glad you have a solution!

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> First, let me explain what I am working with:
>
> I have access to shell account with set up SSH key access; let's name
> this machine host.example.com. I don't have admin rights there, and
> quota is quite tight; I have installed netcat (nc) in ~/bin - it is
> only 22 kB.

Yes, that is great!

> I don't know where to find SOCKS5 proxy, and I don't have 'tsocks' 
> installed either on my computer, or on shell account... I think.

tsocks is packaged in Debian, and surely in other distributions as well. You don't run it on the shell account, but on your own workstation (which I call "laptop" below for clarity).

A SOCKS5 proxy can be generated by ssh by running:

 	[user@laptop] $ ssh -D 1080 shelluser@shellbox

Now:
 	[user@laptop] $ telnet localhost 1080

will demonstrate that local port 1080 is listening. Because you created it with -D to ssh, that local port 1080 *is* a SOCKS5 proxy, created by the local SSH client.

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> Now, solutions:
>
> 1. For reading gitweb at repo.or.cz, and for reading and editing git
>   wiki at http://git.or.cz/gitwiki/ I use one of free HTTP proxies:
>   http://www.4proxy.de (first such proxy I have found that has an
>   option to _not_ obfuscate URLs; it still unnecessary escapes some
>   things like '/' in the query argument).

Great! (Though note that configuring the web browser to use your SSH-created SOCKS5 proxy would let you avoid this escaping since the whole system would be under your control.)

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> 2. For pushing changes to repo.or.cz I use SSH tunnel (I could have
>   used ProxyCommand solution with netcat instead[1]). I run:
>
>   $ autossh -M 2000 -f -N -L 2222:repo.or.cz:22 jnareb@host.example.com
>
>   at startup, and I have set the following in ~/.ssh/config:
>
>   # TP S.A. blocks repo.or.cz
>   Host repo.or.cz
>   	#ssh -f -N -L 2222:repo.or.cz:22 host.example.com
>   	NoHostAuthenticationForLocalhost yes
>   	HostName localhost
>   	Port 2222
>
>   [1] Alternate solution:
>
>   # TP S.A. blocks repo.or.cz
>   Host repo.or.cz
> 	ProxyCommand ssh host.example.com exec /home/jnareb/bin/nc %h %p

Right-o.

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> 3. For fetching changes via git:// protocol from repo.or.cz I use the
>   following setup in git config:
>
>   [core]
>   	gitProxy = ssh-proxy for "repo.or.cz"
>
>   Unfortunately example from Documentation/config.txt with "ssh" as
>   git proxy command doesn't work, and neither putting command with
>   options (e.g. "ssh host.example.com /home/jnareb/bin/nc") doesn't
>   work: the command is _not_ split on whitespace. So I had to use
>   helper script ~/bin/ssh-proxy:
>
>   #!/bin/sh
>
>   ssh host.example.com /home/jnareb/bin/nc "$1" "$2"

Great!

> I hope that would help somebody... and if somebody notices better 
> solution, hs/she would provide me with it :-)

(-:

-- Asheesh.

-- 
A visit to a fresh place will bring strange work.