Re: access wikipedia (walk through the great firewall of China)

2006-12-08 Thread 张韡武
在 2006-12-08五的 06:53 +,Matthew Seaman写道:
 ??? wrote:
  Hello. My office use this method to access wikipedia behind the great
  firewall of China:
  
  1) we have a server in europ, let's call it server;
  2) I run this command on my desktop:
  $ ssh -L 80:en.wikipedia.org:80 server;
  3) everybody in the office edit /etc/hosts, add this line:
  [my_ip_addr] en.wikipedia.org
  
  So my computer become a 'proxy'.
  
  The trouble is I have to keep the ssh running there. The 'proxy' will
  not automatically set up next time I reboot my computer.
  
  Is it possible to install some software to run as a daemon and do this
  proxy?
  
  I think of stunnel, but I have too few knowledge to know if stunnel can
  do this.
 
 There are two general possibilities here:
 
   a) A Web cache/proxy -- squid is the canonical example, but you can
  do this sort of stuff in apache very readily.  I think apache 
  would be a good place for you to start, as most sysadmins have
  at least a passing acquaintance with its configuration.
 
  You'ld need set up a proxy on your European server to redirect
  any web traffic to en.wikipedia.org -- your users would use the
  service exactly as they do at the moment, but they'd put the
  IP of the European server into their hosts file, rather than
  your desktop.  If that is a problem, then you can chain together
  a series of proxies starting with your desktop machine, then
  the European server -- but performance may be a tad slow.

We have a lot of problems accessing any sort of proxy outside China, the
latest technology in the great firewall of China, if you had read the
newspaper, is content-based filtering. 443 port of many foreign servers
are also being blocked.

 
   b) IPsec or other VPN tunnel between your server in Europe and a
  local firewall -- preferably your local firewall should be on
  the egress path from your LAN.  Then you can arrange routing
  so that packets to destinations in Europe pass through the 
  tunnel and use your European server as the gateway to the
  internet.  In this case, there shouldn't be any need for your
  users to have to spoof the address of en.wikipedia.org in 
  their hosts files.  IPSec comes standard with FreeBSD, but
  you'ld probably want to combine it with pf(4) or other firewall
  software which you can use to control redirecting appropriate
  packets through your tunnel.  If IPSec is too mind-mangling
  for you, OpenVPN (in ports) is a pretty good alternative.
 
  You'll almost definitely want to configure a NAT gateway on
  the European server.
  
 Either of these solutions will run automatically on system startup, if
 so configured.  Option (a) will send your web traffic across the net
 in clear-text unless you can chain two proxies together and get creative
 about using HTTPS.  Or you can combine both approaches: use a local HTTP
 proxy with a VPN tunnel to your European server.

Thank you very much for your detailed explanation, I believe me and many
other people on the list is going to benefit from it.

Currently the only website we want very much but being blocked is
wikipedia. Other websites being blocked are mostly about politics and
news, which we are not interested (I think most people in China are not
interested what foreign news says, and getting used to ignore 3rd party
politic information). Wikipedia is an exception because it has a lot of
useful information, not just politics. So basically if wikipedia is
accessible, we are happy. Your general solution looks really complicated
to me that I would like to do it as weekend fun, but probably not going
to be able to maintain it.

Information is like this: you don't need to block all information in
order to prevent people knowing them, you only need to put barrier
higher. There are many ways to workaround (walk-through) the Great
Firewall, but every time when I look into different complicated
solutions, I say to myself is it worthy to spend so much time on it? And
ends up saying to myself, save the time, let's just don't read these
news.

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Re: access wikipedia (walk through the great firewall of China)

2006-12-08 Thread Fabian Keil
张韡武 [EMAIL PROTECTED] wrote:

 Hello. My office use this method to access wikipedia behind the great
 firewall of China:
 
 1) we have a server in europ, let's call it server;
 2) I run this command on my desktop:
 $ ssh -L 80:en.wikipedia.org:80 server;
 3) everybody in the office edit /etc/hosts, add this line:
 [my_ip_addr] en.wikipedia.org
 
 So my computer become a 'proxy'.
 
 The trouble is I have to keep the ssh running there. The 'proxy' will
 not automatically set up next time I reboot my computer.

I think it would be a lot easier if you'd just install Tor
(http://tor.eff.org/).

If you use the security/tor-devel port, you can run it on your company's
gateway and build an intercepting proxy with PF (or natd but I haven't
tried that). This way you wouldn't have to touch the client systems at
all.

Currently the great firewall of Wikipedia prevents Tor users
from contributing, but if you're only interested in reading,
this shouldn't be a problem.

Note that Tor doesn't hide the fact that you are using it.
My understanding is that Tor usage is currently still
legal in China (or at least not prosecuted) and quite popular
there, but of course you should confirm that before you start using
it on an IP address that can be traced back to you.

Fabian
-- 
http://www.fabiankeil.de/


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Re: access wikipedia (walk through the great firewall of China)

2006-12-08 Thread Vince Hoffman



On Fri, 8 Dec 2006, ~_ wrote:


Hello. My office use this method to access wikipedia behind the great
firewall of China:

1) we have a server in europ, let's call it server;
2) I run this command on my desktop:
$ ssh -L 80:en.wikipedia.org:80 server;
3) everybody in the office edit /etc/hosts, add this line:
[my_ip_addr] en.wikipedia.org

So my computer become a 'proxy'.

The trouble is I have to keep the ssh running there. The 'proxy' will
not automatically set up next time I reboot my computer.

Is it possible to install some software to run as a daemon and do this
proxy?

I think of stunnel, but I have too few knowledge to know if stunnel can
do this.


maybe autossh ?
http://www.harding.motd.ca/autossh/
Its in ports
Port:   autossh-1.4a
Path:   /usr/ports/security/autossh
Info:   Automatically restart SSH sessions and tunnels

Otherwise as many other people have said there are may better ways to do 
this.


Vince


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Re: access wikipedia (walk through the great firewall of China)

2006-12-08 Thread John Nielsen
On Friday 08 December 2006 07:12, Vince Hoffman wrote:
 On Fri, 8 Dec 2006, å¼ é~_¡æ­¦ wrote:
  Hello. My office use this method to access wikipedia behind the great
  firewall of China:
 
  1) we have a server in europ, let's call it server;
  2) I run this command on my desktop:
  $ ssh -L 80:en.wikipedia.org:80 server;
  3) everybody in the office edit /etc/hosts, add this line:
  [my_ip_addr] en.wikipedia.org
 
  So my computer become a 'proxy'.
 
  The trouble is I have to keep the ssh running there. The 'proxy' will
  not automatically set up next time I reboot my computer.
 
  Is it possible to install some software to run as a daemon and do this
  proxy?
 
  I think of stunnel, but I have too few knowledge to know if stunnel can
  do this.

 maybe autossh ?
 http://www.harding.motd.ca/autossh/
 Its in ports
 Port:   autossh-1.4a
 Path:   /usr/ports/security/autossh
 Info:   Automatically restart SSH sessions and tunnels

Autossh might do this better/more elegantly, but a quick and dirty solution 
would be something like this:

1) Set up certificates so that ssh server from your machine will 
automatically log in to the server without prompting for a password.

2) Write a script to see if ssh is running and run it if it's not, e.g.

#!/bin/sh
netstat -na | grep LISTEN | grep 80 || \
/usr/bin/ssh -fnN -L 80:en.wikipedia.org:80 server

3) Add an entry to your crontab to run the script every X minutes.

JN
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Re: access wikipedia (walk through the great firewall of China)

2006-12-08 Thread Jona Joachim
On Fri, 08 Dec 2006 14:25:59 +0800
张韡武 [EMAIL PROTECTED] wrote:

 Hello. My office use this method to access wikipedia behind the great
 firewall of China:
 
 1) we have a server in europ, let's call it server;
 2) I run this command on my desktop:
 $ ssh -L 80:en.wikipedia.org:80 server;
 3) everybody in the office edit /etc/hosts, add this line:
 [my_ip_addr] en.wikipedia.org
 
 So my computer become a 'proxy'.
 
 The trouble is I have to keep the ssh running there. The 'proxy' will
 not automatically set up next time I reboot my computer.

You can put the command into /etc/rc.local for it to be executed at
boot time.

Jona
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access wikipedia (walk through the great firewall of China)

2006-12-07 Thread 张韡武
Hello. My office use this method to access wikipedia behind the great
firewall of China:

1) we have a server in europ, let's call it server;
2) I run this command on my desktop:
$ ssh -L 80:en.wikipedia.org:80 server;
3) everybody in the office edit /etc/hosts, add this line:
[my_ip_addr] en.wikipedia.org

So my computer become a 'proxy'.

The trouble is I have to keep the ssh running there. The 'proxy' will
not automatically set up next time I reboot my computer.

Is it possible to install some software to run as a daemon and do this
proxy?

I think of stunnel, but I have too few knowledge to know if stunnel can
do this.

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Re: access wikipedia (walk through the great firewall of China)

2006-12-07 Thread 张韡武
在 2006-12-08五的 14:25 +0800,张韡武写道:
 Hello. My office use this method to access wikipedia behind the great
 firewall of China:
 
 1) we have a server in europ, let's call it server;
 2) I run this command on my desktop:
 $ ssh -L 80:en.wikipedia.org:80 server;
 3) everybody in the office edit /etc/hosts, add this line:
 [my_ip_addr] en.wikipedia.org
 
 So my computer become a 'proxy'.
 
 The trouble is I have to keep the ssh running there. The 'proxy' will
 not automatically set up next time I reboot my computer.
 
 Is it possible to install some software to run as a daemon and do this
 proxy?
 
 I think of stunnel, but I have too few knowledge to know if stunnel can
 do this.

Forgot to mention another requirement is to be able to automatically
re-connect if the ssh connection drops. It's difficult to maintain a
connection the whole day..

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Re: access wikipedia (walk through the great firewall of China)

2006-12-07 Thread Matthew Seaman
??? wrote:
 Hello. My office use this method to access wikipedia behind the great
 firewall of China:
 
 1) we have a server in europ, let's call it server;
 2) I run this command on my desktop:
 $ ssh -L 80:en.wikipedia.org:80 server;
 3) everybody in the office edit /etc/hosts, add this line:
 [my_ip_addr] en.wikipedia.org
 
 So my computer become a 'proxy'.
 
 The trouble is I have to keep the ssh running there. The 'proxy' will
 not automatically set up next time I reboot my computer.
 
 Is it possible to install some software to run as a daemon and do this
 proxy?
 
 I think of stunnel, but I have too few knowledge to know if stunnel can
 do this.

There are two general possibilities here:

  a) A Web cache/proxy -- squid is the canonical example, but you can
 do this sort of stuff in apache very readily.  I think apache 
 would be a good place for you to start, as most sysadmins have
 at least a passing acquaintance with its configuration.

 You'ld need set up a proxy on your European server to redirect
 any web traffic to en.wikipedia.org -- your users would use the
 service exactly as they do at the moment, but they'd put the
 IP of the European server into their hosts file, rather than
 your desktop.  If that is a problem, then you can chain together
 a series of proxies starting with your desktop machine, then
 the European server -- but performance may be a tad slow.

  b) IPsec or other VPN tunnel between your server in Europe and a
 local firewall -- preferably your local firewall should be on
 the egress path from your LAN.  Then you can arrange routing
 so that packets to destinations in Europe pass through the 
 tunnel and use your European server as the gateway to the
 internet.  In this case, there shouldn't be any need for your
 users to have to spoof the address of en.wikipedia.org in 
 their hosts files.  IPSec comes standard with FreeBSD, but
 you'ld probably want to combine it with pf(4) or other firewall
 software which you can use to control redirecting appropriate
 packets through your tunnel.  If IPSec is too mind-mangling
 for you, OpenVPN (in ports) is a pretty good alternative.

 You'll almost definitely want to configure a NAT gateway on
 the European server.
 
Either of these solutions will run automatically on system startup, if
so configured.  Option (a) will send your web traffic across the net
in clear-text unless you can chain two proxies together and get creative
about using HTTPS.  Or you can combine both approaches: use a local HTTP
proxy with a VPN tunnel to your European server.

Cheers,

Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.   7 Priory Courtyard
  Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
  Kent, CT11 9PW



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