Port blocking workaround

Question

I recently was on a visit for a few days where my primary internet access was through verizon, which I eventually discovered blocks SMTP ports. I had to improvise a workaround to send mail, but I burned a lot of effort figuring everything out.

So, my question is, what's the best general strategy for dealing with on-the-road network connectivity, given that my home PC will be powered off and I'll be carrying a netbook.

-- None of the answers to date is really satisfactory, and I've given the subject more thought. It finally came to me that the solution is the very earliest technology the public used to get to the internet. Back in the stone age of the internet, you had to be an institution to have internet access. Those institutions could allow their employees or other associates to dial in to their sites, and from there do whatever the institutions permitted, but you were pretty much tethered. If your internet access was through a school, and you graduated, you were out of luck. If your access was through your job, and you changed jobs, your internet access went away with it.

-- One of the first cracks in this institutional wall was netcom. I'm not sure what they were officially, but they started selling dialup access to unix shell accounts for about $30/month. This was about 1995. Ostensibly, these shell accounts let you do simple things like send email and use FTP from text-based client programs. Everything was run over a text based interface suitable for a "glass tty" terminal which was standard for the time. This was pre-web - there were no browsers yet - but as we all know that all changed very rapidly. Suddenly, there was all this cool browsing and graphics that everyone was using, but only from work - because you had to be an institution to connect to the internet, and users only connected to institutions by text based dialup.

-- The programs that changed all this were "slirp" and "tia". These programs ran on unix shell accounts, and used PPTP to tunnel internet traffic over the dialup text connection, back to your home pc, giving you full internet access over your dialup line. The slirp/tia era didn't last long, soon netcom (and others) started offering dialup that did exactly the same things but didn't require messing with shell accounts or finicky setup of your pc's network stack.

-- the main thing (and the answer to my question) is that "slirp" effectively teleported your network identity to the host you dialed in to. And that is what I want for my traveling PC - a way to take whatever brain damaged, restricted, censored, or otherwise limited internet access while on the road and teleport it to a nice unrestricted host.

I think what I'm looking for is a mandatory VPN, perhaps one that is configurable to use port 80 or some other port that is found to be available.

Answer 1

I had verizon too. I got around their brutal blocking tactics by using non-standard port #'s. This will usually result in ugly access to your server

http://myserver:8989/default.aspx

or whatever...

But, you can pay a company like dnsexit.com to route DNS requests to

http://myserver.com/

to

http://myserver.com:8989/

invisibly. The same can be done with SMTP, HTTP, whatever. Just make sure to telnet into the port after opening up a server to listen via TCP so you can test the port is not blocked by verizon before you setup the port forwarding.

Answer 2

It is hard to believe Verizon blocks SMTP ports, but here is a way: If you are able to keep your home PC turned on, then I recommend installing Bitwise SSHD on it, then open port 22 in your firewall. Then, from your netbook, if you need access to the Verizon SMTP server, you can use the Tunnelier client to tunnel through, via your desktop at home.

Answer 3

Two ways.

1) Most internet service providers provide alternative port numbers for remote use. e.g. for remote SMTP I have to use 587 and I have to authenticate first. But this works nearly everywhere.

2) If 1 fails then simply use the SMTP server local to that network. In your case verizon should have an SMTP server that you can use for your outbound email.

I've actually looked that up. Guess what? Verizon uses outgoing.verizon.net port 587! So you can just change your email program to use that server as your smtp server while you're on that network. When you move to another network you can change back to 1) or use 2 again etc.

Answer 4

The solution I eventually settled on was to use "putty" ssh client which has built in options to create a ssh tunnel. I log into the smtp server and use putty to tunnel outgoing mail to it. This isn't a general solution, but does take care of the most pressing problem (if the ssh port is open)