Re: [tlug] SSH'ing to home

[Jim <jep200404@example.com>]

David Bennett wrote:

> I am not sure what a tunnel does. 

It's a communication technique for transporting one kind of 
network communication over a different kind of network 
communication. It's used as a workaround for networking 
limitations. 

Here's simple example. My grandma wants to send a letter 
very fast to my mom who is overseas visiting relatives. 
Let's say my grandma wants send a letter to my mom much faster 
than any post office can deliver. That is the network 
limitation. Of course, grandma and mom are also afraid of 
computers. My grandma scribbles a note on paper and gives 
it to me saying "Take this to the post office and mail 
it to your mom fast", and frets about how the letter will 
arrive too late.  Without consulting my grandma, 
I skip the post office. Instead I scan the paper at home 
and email it as an attachment to a cousin that mom is staying 
with, saying "Please print the attachment and give it to my mom". 
A few hours later the cousin checks his email, 
prints out the attachment and gives it to my mom saying 
to her "this note arrived from your mom (Jim's grandma)". 

Everything from me receiving the original note, 
to my cousing handing another piece of paper to my 
mom, is the tunnel. 

In your situation, a possible (perhaps likely) network 
limitation is that the firewall at work blocks outgoing 
packets addressed to port 22 (ssh). A workaround 
would be to send the ssh communication through through 
http requests and replies.  The ssh data would be 
transformed into valid http requests or replies when 
entering the tunnel, and untransformed from http back 
into ssh data at the other end of the tunnel. 

> I have a vague idea of what [tunneling] is, but I am not
> clear on specifics nor about how to implement one. (or even if it
> would help)

Tunneling is a bit of a trick and its easy to get confused by it, 
like being in a hall of mirrors. 

Because of this, one tries to use simpler solutions before 
resorting to tunneling. Also, because it is so easy to get 
confused about, people who explain tunneling need to be 
very clear, avoiding pronouns, and being redundantly explicit 
about subject and objects and sources and destinations in 
every sentence.