Monthly Archives: March 2018

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Password rules

Some very basic rules for managing your passwords:

  1. Don’t even think about using “password” as your password. That’s the number one most used password in the world.
  2. Consider using a password manager. No one will ever guess that your password is qwb5Qauz36H9Kleqyotx and with a password manager, you won’t have to remember it.
  3. If you must use a password you can remember, at least use a passphrase. “SixSillySwansSangSonnets” is much more secure than “Tr0ubad0r” (and a darn sight easier to remember the correct spelling).
  4. Never, ever, ever use the same password on two different sites. In short: if one site has a breach and the bad guys get hold of your username and password, they’re going to try using them on other sites as well.

    5. Faithfully following those rules doesn’t guarantee that none of your accounts will ever get hacked, too much of that’s out of your hands. But they’re a solid start and they’ll definitely help limit the damage.

    A non-technical relative admits to not understanding why people would use a password manager. Couldn’t someone just hack your password manager?

    Yes. That could potentially happen. The aforementioned password rules also apply when setting the password for your password manager.

    And you have to ask yourself, which system is more secure? A well-vetted, “battle tested” password manager (and I’m referring to the likes of LastPass, 1Password, or KeePass), storing passwords which are composed of 20 random letters and numbers? Or just using the site’s name with a couple letters and maybe a number?

    And which is easier? Keeping track of a single strong password for the password manager? Or trying to remember what password you used for 30, 40, or more different web sites? (Hint: you’re gonna remember the Six Silly Swans example for a long time.) The main reason people re-use passwords is that they need to keep track of so doggone many of them!

    The idea behind a password manager is that you only have to remember one really good password, and then the password manager remembers the rest of them.

    And the good password managers (I personally use LastPass and KeePass) use heavy-duty encryption. If you use a good password, it’s extraordinarily unlikely that anyone’s going to break into your password manager by brute-force guessing.

    (Image via Life of Pix on Pexels.com under Creative Commons 1.0 Universal)

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Finding Your Router’s Public IP Address

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It’s easy enough to find your home router’s public facing IP address (the one your ISP assigns) via a Google search; they even make it the first result on the page. But what if you want to find it via a script?

That’s the challenge I’m trying to solve. What’s more, I want to do this without calling something on an external service. I’ll only be looking it up once every five minutes or so, but I’d prefer to not be a nuisance. (And if something goes wrong and my script runs in a tight loop, I’d rather not have the polling hammer someone else’s server.)

I found a script on the Linux & Things blog which almost does what I want. That script doesn’t quite work for me though, my route command doesn’t flag the default gateway.

But that’s OK, the bulk of what that script does is to look up the local network’s name for the router. That’s a nice bit of robustness, just in case the router’s name does change for some reason (e.g. switching from Fios to Comcast, you’d get a new router and the new router would likely have a different default name). But for my purposes, it’s good enough to know that the router’s name is always going to be Fred. (No, not really, that would be silly. My router’s real name is Ethel.)

So from a bash prompt, we end up with this snippet of code:

external_address=$(nslookup Fred.home | grep Address | tail -1 | awk ‘{print $2}’)

That one-liner really breaks down to five parts.

nslookup Fred.home looks up Fred’s entry in the local DNS. What I get is something similar to:

Server: 192.168.1.1
Address: 192.168.1.1#53

Name: Fred.home
Address: 192.168.1.1
Name: Fred.home
Address: 172.217.8.14

Now none of that’s my real network information, but what we’re after is that last “Address” line.

Piping the output of nslookup through grep Address throws away every line which doesn’t contain the word “Address”, leaving this:

Address:        192.168.1.1#53
Address: 192.168.1.1
Address: 172.217.8.14

Getting closer, next, it gets piped through tail -1 which grabs just the last line:

Address: 172.217.8.14

Excellent! That’s almost what we want.

The next step in the chain is to run it through awk '{print $2}' which uses the AWK tool to output just the second token in the stream.

Finally, the entire thing is wrapped in the $() operator, which captures the output of those four steps and allows us to assign them to the 

external_address

variable, which allows the external address to be used elsewhere:

external_address=$(nslookup Fred.home | grep Address | tail -1 | awk ‘{print $2}’)
echo $external_address
172.217.8.14

This (obviously) runs at a bash prompt. I’ve tried it out on Ubuntu and the Windows Subsystem for Linux, though I can’t imagine it wouldn’t work on other distributions as well. Most of the magic in this is text parsing. The Windows version of nslookup provides similar output, just formatted differently; there’s no reason a PowerShell script couldn’t do some similar processing to find the address.