We Moved!

We moved to here: http://sandrylogan.wordpress.com

Swinging from the crane

Logan’s cellphone is really crap at taking pictures (and the Millerphone got squashed under the wheels of a large truck that i had just overtaken on the Information Superhighway) so this is all we have. The photo was taken out of Logan’s office window and show’s a guy sitting on a sort of chair suspended from the top of the crane-thing that has been drilling holes in the building site all week. He was pushing himself off away from the crane, spraying a pressure hose onto the top floor library windows before swinging back onto the crane and starting again.

04-12-09_150645

Pre RTFM

Yesterday, there was an email about the photocopier being out of service and an engineer having been called. Today I received this in my email:

Dear All,

If there is a fault with the photocopier please inform and liaise with Harriet on extn 4371.

Yesterday’s message would appear to be a false alarm.
In future can staff please check that the copier is turned on/plugged in before reporting a fault.

Many thanks

Admin

Is it only me, or is that really funny?

SSH Port Forwarding Tunnels

This is a handy trick to view pages directly on a web server running on a machine that is not connected directly to the Internet. Imagine that you have a laboratory running on a LAN, the machines in the lab can connect to the Internet through a gateway, proxy server or somesuch, but you can’t connect directly to them from outside… but you can connect to the gateway from outside.

Let’s assume your gateway is a machine called “something.somewhere.com” and it is connected to a LAN with a network address of 192.168.200.0/24.  If you’re on a Linux box, you can create your tunnel like this:

ssh username@something.somewhere.com -L 8080:192.168.200.10:80

What this means:

ssh username@something.somewhere.com 

– make a secure shell connection to the gateway, where you will log in as “username”. Presumably this is no great mystery.

-L 8080:192.168.200.10:80

-L means forward a Local Port, in this case 8080, which is forwarded to port 80 on the machine with IP address 192.168.200.10

When you hit enter you connect to something.somewhere.com machine over SSH, give your passwd and log in.

You would now point your browser at http://localhost:8080 to see the web site on 192.168.200.10.

——————————–

Can I do that with windows, say with PuTTY?

Yes. In your PuTTY session settings put the address of the machine that you wish to secure shell to, in this case something.somewhere.com

putty.tunnelsession_main

Now switch to the SSH/Tunnels dialogue:

putty.tunnel.tunnel_01

Put the Local port number (8080 in this case) into the Source Port field and put the destination address and the destination port in the the Destination field.

Hit the Add button to add these settings to the session.

putty.tunnel.tunnel_02

Now hit open and log in with your usual user name and passwd. You can view the web site on 192.168.200.10 in your browser like this, (same as the previous example): http://localhost:8080

Note: If the machine that you are tunneling through can resolve the names of the machines on the remote LAN, you can specify the destination as a hostname:port combination like this:

putty.tunnel.tunnel_03

References

Gheorghiu, G.,, 2006. SSH tunnelling with PuTTY. [Online] Available at: http://agiletesting.blogspot.com/2006/05/ssh-tunnelling-with-putty.html [Accessed 1 November 2009].

Tatham, S., 2009. PuTTY User Manual. [Online] available at: http://the.earth.li/~sgtatham/putty/0.60/htmldoc/Chapter3.html#using-port-forwarding [Accessed 1 November 2009].

Flickenger, R., 2003. Linux Server Hacks. 1st ed. O’Reilly.

http://agiletesting.blogspot.com/2006/05/ssh-tunnelling-with-putty.html