c0d3 :: j0rg3

A collection of tips, tricks and snips. A proud Blosxom weblog. All code. No cruft.

Sat, 04 Mar 2017

Official(ish) deep dark onion code::j0rg3 mirror

Recently I decided that I wanted my blog to be available inside of the Deep, Dark Onion (Tor).

First time around, I set up a proxy that I modified to access only the clear web version of the blog and to avail that inside Tor as a ‘hidden service’.

My blog is hosted on equipment provided by the kind folk at insomnia247.nl and I found that, within a week or so, the address of my proxy was blocked. It’s safe for us to assume that it was simply because of the outrageous popularity it received inside Tor.

By “safe for us to assume” I mean that it is highly probable that no significant harm would come from making that assumption. It would not be a correct assumption, though.

What’s more true is that within Tor things are pretty durn anonymous. Your logs will show Tor traffic coming from 127.0.0.1 only. This is a great situation for parties that would like to scan sites repeatedly looking for vulnerabilities — because you can’t block them. They can scan your site over and over and over. And the more features you have (e.g., comments, searches, any form of user input), the more attack vectors are plausible.

So why not scan endlessly? They do. Every minute of every hour.

Since insomnia247 is a provider of free shells, it is incredibly reasonable that they don’t want to take the hit for that volume of traffic. They’re providing this service to untold numbers of other users, blogs and projects.

For that reason, I decided to set up a dedicated mirror.

Works like this: my blog lives here. I have a machine at home which uses rsync to make a local copy of this blog. Immediately thereafter it rsyncs any newly gotten data up to the mirror in onionland.

After consideration, I realized that this was also a better choice just in case there is something exploitable in my blog. Instead of even risking the possibility that an attacker could get access to insomnia247, they can only get to my completely disposable VPS which has hardly anything on it except this blog and a few scripts to which I’ve already opened the source code.

I’ve not finished combing through but I’ve taken efforts to ensure it doesn’t link back to clear web. To be clear, there’s nothing inherently wrong with that. Tor users will only appear as the IP address of their exit node and should still remain anonymous. To me, it’s just onion etiquette. You let the end-user decide when they want to step outside.

To that end, the Tor mirror does not have the buttons to share to Facebook, Twitter, LinkedIn, Google Plus.

That being said, if you’re a lurker of those Internet back-alleys then you can find the mirror at: http://aacnshdurq6ihmcs.onion

Happy hacking, friends!


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Permalink: 20170304.deep.dark.onion

Thu, 06 Jun 2013

Managing to use man pages through simple CLI tips

Recently, an author I admire and time-honored spinner of the Interwebs, Tony Lawrence emphasized the value of using man pagesmanual pagesDocumentation available from the command line.
> man ls
as a sanity check before getting carried away with powerful commands. I didn’t know about this one but he has written about a situation in which killall could produce some shocking, and potentially quite unpleasant, results.

Personally, I often quickly check man pages to be certain that I am using the correct flags or, as in the above case, anticipating results that bear some resemblance to what is actually likely to happen. Yet, it seems many people flock toward SERPSearch Engine Results Page A tasteful replacement for mentioning any particular search-engine by name.
Also useful as a verb:
I dunno. You’ll have to SERP it.
s for this information.

Perhaps the most compelling reason to head for the web is leaving the cursor amid the line you’re working on, without disturbing the command. SERPing the command however, could easily lead you to information about a variant that is more common than the one available to you. More importantly, the information retrieved from the search engine is almost certainly written by someone who did read the man page — and may even come with the admonishment that you RTFMRead The F#!$!*#’n Manual as a testament to the importance of developing this habit.

This can be made easier with just a few CLI shortcuts.

<CTRL+u> to cut what you have typed so far and <CTRL+y> to paste it back.

That is, you press <CTRL+u> and the line will be cleared, so you can then type man {command} and read the documentation. Don’t hesitate to jot quick notes of which flags you intend to use, if needed. Then exit the man page, press <CTRL+y> and finish typing right where you left off.

This is another good use for screen or tmux but let’s face it. There are times when you don’t want the overhead of opening another window for a quick look-up and even instances when these tools aren’t available.

A few other tips to make life easier when building complex commands:

Use the command fc to open up an editor in which you can build your complex command and, optionally, even save it as a shell script for future reuse.

Repeat the last word from the previous command (often a filename) with <ALT+.> or use an item from the last command by position, in reverse order:
> ls -lahtr *archive*
<ALT+1+.> : *archive*
<ALT+2+.> : -lahtr
<ALT+3+.> : ls

You can also use Word Designators to use items from history, such as adding sudo to the last command typed by:
sudo !!

This allows for tricks like replacing bits of a previous command:
!:s/misspelled/corrected/

Lastly, if you need a command that was typed earlier, you can search history by pressing <CTRL+r> and start typing an identifying portion of the command.

(Note: I have used these in Zsh and Bash, specifically. They can, however, be missing or overwritten — if a feature you want isn’t working, you can bind keys in a configuration file. Don’t just write it off, once you’ve solved the problem it will never again be an intimidating one.)

Happy hacking!


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Permalink: 20130606.managing.to.use.man.pages

Thu, 23 May 2013

GNU Screen: Roll your own system monitor

Working on remote servers, some tools are practically ubiquitous — while others are harder to come by. Even if you’ve the authority to install your preferred tools on every server you visit, it’s not always something you want to do. If you’ve hopped on to a friend’s server just to troubleshoot a problem, there is little reason to install tools that your friend is not in the habit of using. Some servers, for security reasons, are very tightly locked down to include only a core set of tools, to complicate the job of any prying intruders. Or perhaps it is a machine that you normally use through a graphical interface but on this occasion you need to work from the CLI.

These are very compelling reasons to get comfortable, at the very least, with tools like Vim, mail, grep and sed. Eventually, you’re likely to encounter a situation where only the classic tools are available. If you aren’t competent with those tools, you’ll end up facing the obstacle of how to get files from the server to your local environment where you can work and, subsequently, how to get the files back when you’re done. In a secured environment, this may not be possible without violating protocols.

Let’s take a look at how we can build a makeshift system monitor using some common tools. This particular configuration is for a server running PHP, MySQL and has the tools Htop and mytop installed. These can easily be replaced with top and a small script to SHOW FULL PROCESSLIST, if needed. The point here is illustrative, to provide a template to be modified according to each specific environment.

(Note: I generally prefer tmux to Gnu Screen but screen is the tool more likely to be already installed, so we’ll use it for this example.)

We’re going to make a set of windows, by a configuration file, to help us keep tabs on what is happening in this system. In so doing, we’ll be using the well-known tools less and watch. More specifically, less +F which tells less to “scroll forward”. Other words, less will continue to read the file making sure any new lines are added to the display. You can exit this mode with CTRL+c, search the file (/), quit(q) or get back into scroll-forward mode with another uppercase F.

Using watch, we’ll include the “-d” flag which tells watch we want to highlight any changes (differences).

We will create a configuration file for screen by typing:

> vim monitor.screenrc

In the file, paste the following:

# Screen setup for system monitoring
# screen -c monitor.screenrc
hardstatus alwayslastline
hardstatus string '%{= kG}[ %{G}%H %{g}][%= %{=kw}%?%-Lw%?%{r}(%{W}%n*%f%t%?(%u)%?%{r})%{w}%?%+Lw%?%?%= %{g}][%{B}%Y-%m-%d %{W}%c %{g}]'

screen -t htop 0 htop
screen -t mem 1 watch -d "free -t -m"
screen -t mpstat 2 watch -d "mpstat -A"
screen -t iostat 3 watch -d "iostat"
screen -t w 4 watch -d "w"
screen -t messages 5 less +F /var/log/messages
screen -t warn 6 less +F /var/log/warn
screen -t database 7 less +F /srv/www/log/db_error
screen -t mytop 8 mytop
screen -t php 9 less +F /srv/www/log/php_error

(Note: -t sets the title, then the window number, followed by the command running in that window)

Save the file (:wq) or, if you’d prefer, you can grab a copy by right-clicking and saving this file.

Then we will execute screen using this configuration, as noted in the comment:

> screen -c monitor.screenrc

Then you can switch between windows using CTRL+a, n (next) or CTRL+a, p (previous).

I use this technique on my own computers, running in a TTY different from the one used by X. If the graphical interface should get flaky, I can simply switch to that TTY (e.g., CTRL+ALT+F5) to see what things are going on — and take corrective actions, if needed.


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Permalink: 20130523.gnu.screen.system.monitor