Fooling around with the Collatz Sequence

Spent some time working on https://projecteuler.net/problem=14

It was fun, and I produced:

Crunching Collatz Sequence...go make some coffee
 Number 13 also has same number of terms as previous record
New record of 18 iterations found for 14
 Number 15 also has same number of terms as previous record
New record of 21 iterations found for 18
 Number 19 also has same number of terms as previous record
New record of 24 iterations found for 25
New record of 112 iterations found for 27
New record of 113 iterations found for 54
 Number 55 also has same number of terms as previous record
New record of 116 iterations found for 73
New record of 119 iterations found for 97
New record of 122 iterations found for 129
New record of 125 iterations found for 171
New record of 128 iterations found for 231
 Number 235 also has same number of terms as previous record
New record of 131 iterations found for 313
New record of 144 iterations found for 327
New record of 145 iterations found for 649
 Number 654 also has same number of terms as previous record
 Number 655 also has same number of terms as previous record
 Number 667 also has same number of terms as previous record
New record of 171 iterations found for 703
New record of 179 iterations found for 871
New record of 182 iterations found for 1161
New record of 183 iterations found for 2223
 Number 2322 also has same number of terms as previous record
 Number 2323 also has same number of terms as previous record
New record of 209 iterations found for 2463
New record of 217 iterations found for 2919
New record of 238 iterations found for 3711
New record of 262 iterations found for 6171
New record of 268 iterations found for 10971
New record of 276 iterations found for 13255
New record of 279 iterations found for 17647
 Number 17673 also has same number of terms as previous record
New record of 282 iterations found for 23529
New record of 308 iterations found for 26623
New record of 311 iterations found for 34239
 Number 35497 also has same number of terms as previous record
New record of 324 iterations found for 35655
New record of 340 iterations found for 52527
New record of 351 iterations found for 77031
New record of 354 iterations found for 106239
New record of 375 iterations found for 142587
New record of 383 iterations found for 156159
New record of 386 iterations found for 216367
New record of 443 iterations found for 230631
New record of 449 iterations found for 410011
New record of 470 iterations found for 511935
New record of 509 iterations found for 626331
New record of 525 iterations found for 837799

The record number of terms was 525, Produced by number 837799
RUN FINISHED; exit value 0; real time: 320ms; user: 0ms; system: 300ms

This felt good, so I bumped the target number up to 1 billion and got


Crunching Collatz Sequence...go make some coffee
 Number 13 also has same number of terms as previous record
New record of 18 iterations found for 14
 Number 15 also has same number of terms as previous record
New record of 21 iterations found for 18
 Number 19 also has same number of terms as previous record
New record of 24 iterations found for 25
New record of 112 iterations found for 27
New record of 113 iterations found for 54
 Number 55 also has same number of terms as previous record
New record of 116 iterations found for 73
New record of 119 iterations found for 97
New record of 122 iterations found for 129
New record of 125 iterations found for 171
New record of 128 iterations found for 231
 Number 235 also has same number of terms as previous record
New record of 131 iterations found for 313
New record of 144 iterations found for 327
New record of 145 iterations found for 649
 Number 654 also has same number of terms as previous record
 Number 655 also has same number of terms as previous record
 Number 667 also has same number of terms as previous record
New record of 171 iterations found for 703
New record of 179 iterations found for 871
New record of 182 iterations found for 1161
New record of 183 iterations found for 2223
 Number 2322 also has same number of terms as previous record
 Number 2323 also has same number of terms as previous record
New record of 209 iterations found for 2463
New record of 217 iterations found for 2919
New record of 238 iterations found for 3711
New record of 262 iterations found for 6171
New record of 268 iterations found for 10971
New record of 276 iterations found for 13255
New record of 279 iterations found for 17647
 Number 17673 also has same number of terms as previous record
New record of 282 iterations found for 23529
New record of 308 iterations found for 26623
New record of 311 iterations found for 34239
 Number 35497 also has same number of terms as previous record
New record of 324 iterations found for 35655
New record of 340 iterations found for 52527
New record of 351 iterations found for 77031
New record of 354 iterations found for 106239
New record of 375 iterations found for 142587
New record of 383 iterations found for 156159
New record of 386 iterations found for 216367
New record of 443 iterations found for 230631
New record of 449 iterations found for 410011
New record of 470 iterations found for 511935
New record of 509 iterations found for 626331
New record of 525 iterations found for 837799
New record of 528 iterations found for 1117065
 Number 1126015 also has same number of terms as previous record
New record of 531 iterations found for 1501353
 Number 1564063 also has same number of terms as previous record
New record of 557 iterations found for 1723519
New record of 560 iterations found for 2298025
New record of 563 iterations found for 3064033
New record of 584 iterations found for 3542887
New record of 597 iterations found for 3732423
New record of 613 iterations found for 5649499
New record of 665 iterations found for 6649279
New record of 686 iterations found for 8400511
New record of 689 iterations found for 11200681
New record of 692 iterations found for 14934241
New record of 705 iterations found for 15733191
New record of 706 iterations found for 31466382
 Number 31466383 also has same number of terms as previous record
New record of 745 iterations found for 36791535
New record of 950 iterations found for 63728127
New record of 951 iterations found for 127456254
 Number 127456255 also has same number of terms as previous record
New record of 954 iterations found for 169941673
New record of 957 iterations found for 226588897
New record of 965 iterations found for 268549803
New record of 966 iterations found for 537099606
 Number 537099607 also has same number of terms as previous record
New record of 987 iterations found for 670617279

The record number of terms was 987, Produced by number 670617279

RUN FINISHED; exit value 0; real time: 7m 6s; user: 760ms; system: 7m 4s

This was single-core on a Virtual machine running on a core i5 (sandybridge).

I am not sure I want to test what 4 billion looks like without finding a way to use more than one thread.

I don’t think the answer is wrong, but I might have made a mistake I don’t yet realize :)

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x-cycle: insert a rotating X-Forwarded-For Header

I made a pretty simple chrome extension that allows you to configure a list of IP addresses, as well as a target host and it will insert an X-Forwarded-For header into the requests for the target host, and switch to the next IP in your configured list after about 6 requests.

This was useful to me when testing our a Web Application Firewall.

I have attempted to publish it in the Chrome Store several times, and the experience is just horrible. It gets published, then without reason, it gets taken down until I raise a support ticket. One day later, it gets published again with no explanations or apologies offered, and the cycle repeats again.

If you’re in luck, it may be available in the chrome store here: https://chrome.google.com/webstore/detail/x-cycle/bnlmhngacoghehikmhlcmpkbbnjdifca

Otherwise, you can download the latest copy I have hosted on my server: https://nucco.org/files/x-cycle.crx

If you care for this sort of thing, the sha1sum of the current file on my server should be:

c436ae78256a212851ee862e19fe51d08eab0049 *x-cycle.crx

Enjoy.

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Walled Gardens need Improvement

I came face to face with “The Man” recently, and lost hopelessly.

You see, I spent two weekends working on a relatively basic Chrome Extension that I find useful in my day job; I often have to test a Web App Firewall, and usually you need to simulate traffic from multiple different source clients. The easiest way to do this for HTTP is to use the X-Forwarded-For (XFF) header, and configure your WAF to trust it. So, I thought, If i made an extension to automatically switch the XFF header, it would take some tedium out of this process.

I spent a bit of time on the Eloquent Javascript and the Chrome Developer Documentation, and over two weekends, came up with a slightly configurable and reasonably usable extension that allows you to inject XFF header into requests to a target server you configure. I called it “x-cycle“.

Feeling proud of my accomplishment, I push this to the Chrome Store  as a Developer Tool (paid a $5 verification fee in the process).

I spend the next 12 hours eagerly searching for my extension in the Chrome Web Store, hoping that my first ever extension would show up. After frustration with not finding it, I decide to go to my Chrome Developer Dashboard and check. “At least one of your items has been removed from the store because it did not comply with our policies or terms of service.” Huh? No email, no notification, and no specification of which terms I have violated, and very little I can do about it. 

Nobody will get to use my extension, unless I distribute it manually, and Chrome already makes it near impossible to distribute an extension outside of the Chrome Store, so, I won’t get much traction there, regardless of how much I think people with my kind of job would find this tool useful.

I understand more vividly why walled gardens can be a problem. Previously, I have always preferred Android to iOS because I felt like Google didn’t do too much to dictate what kind of software I can use on my phone compared to Apple, but looking at Chrome, it seems like I never considered the fact that Chrome has become a walled Garden, and one that badly needs to improve its engagement at that.

If you take down someone’s work, you need to at least explain why, so that they can work on resolving it. I get the distinct feeling that some Reviewer just saw “X-Forwarded-For”, googled it, and saw it as a way to “mask” your IP address, and thought “Oh No! Hacking Tool!!” and took it down. This would be a real shame.

Any experienced web admin knows that you don’t trust X-Forwarded-For, unless it was set by a device that you control, thus there is limited scope for abuse of this extension, even for people who are intent on mischief. The policy for trusting XFF is that you strip whatever you received, and then inject the value that you are going to trust. Someone who tests a WAF is both in control of the client and the web-server, and can configure it to trust this header, and this is what makes this extension useful in my view.

I have submitted a support ticket to some Google Support service that took some Googling to find hoping I would get back a more actionable response whenever they do get round to it.

Until then, twiddling thumbs and wondering whether the “open” web we so proudly proclaim is not really just a walled garden with tremendous power in the hands of the people who make web browsers. It is probably little wonder then that practically all browsers are free of charge; they trade the cost for the users, which in turn amplify the power of the browser vendor. They can then hold advertisers, publishers and developers to ransom. Hmmm.

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Looking for an IPv6 Tunnel?

Don’t bother trying Sixxs if you don’t intend to use your work address. The haughty folks over there might put you off IPv6 for good.

Head straight to Tunnel Broker where you can have a tunnel authorized in 5 minutes or less, with no need to read through a laundry list of Email providers you are not allowed to use.

Looking forward to beating my router into shape to provide connectivity to my LAN.

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[in brief] compiling libgcrypt 1.6.3

While building this library, i ran into errors finding libgpg-error 1.11.

There is a small bug in libgcrypt’s configure script for finding this library. It tells you to set –with-libgpg-error-prefix, but it actually ultimately looks for the location of this library from the variable –with-gpg-error-prefix. You should set –with-gpg-error-prefix instead of –with-libgpg-error-prefix, if your libgpg-error is installed to a non-standard location.

 

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Installing pycrypto on Windows 8

While trying to install pycrypto on Windows 8, because it was a requirement for “paramiko” which I needed for some SSH stuff, I kept running into failure after another. To summarise, you need to have Visual Studio 2008 installed (there is an express version available free, and there is also likely a microsoft SDK package that includes the Visual C++ 9.0 compiler). After sorting all of these out however, I still had one persistent type of problem:

warning: GMP or MPIR library not found; Not building Crypto.PublicKey._fastmath.
 Traceback (most recent call last):
 File "<string>", line 1, in <module>
 File "c:\users\fanen\appdata\local\temp\pip_build_Fanen\pycrypto\setup.py", line 456, in <module>
 core.setup(**kw)
 File "c:\Python27\lib\distutils\core.py", line 152, in setup
 dist.run_commands()
 File "c:\Python27\lib\distutils\dist.py", line 953, in run_commands
 self.run_command(cmd)
 File "c:\Python27\lib\distutils\dist.py", line 972, in run_command
 cmd_obj.run()
 File "c:\Python27\lib\site-packages\setuptools\command\install.py", line 53, in run
 return _install.run(self)
 File "c:\Python27\lib\distutils\command\install.py", line 563, in run
 self.run_command('build')
 File "c:\Python27\lib\distutils\cmd.py", line 326, in run_command
 self.distribution.run_command(command)
 File "c:\Python27\lib\distutils\dist.py", line 972, in run_command
 cmd_obj.run()
 File "c:\Python27\lib\distutils\command\build.py", line 127, in run
 self.run_command(cmd_name)
 File "c:\Python27\lib\distutils\cmd.py", line 326, in run_command
 self.distribution.run_command(command)
 File "c:\Python27\lib\distutils\dist.py", line 972, in run_command
 cmd_obj.run()
 File "c:\users\fanen\appdata\local\temp\pip_build_Fanen\pycrypto\setup.py", line 253, in run
 build_ext.run(self)
 File "c:\Python27\lib\distutils\command\build_ext.py", line 337, in run
 self.build_extensions()
 File "c:\users\fanen\appdata\local\temp\pip_build_Fanen\pycrypto\setup.py", line 150, in build_extensions
 build_ext.build_extensions(self)
 File "c:\Python27\lib\distutils\command\build_ext.py", line 446, in build_extensions
 self.build_extension(ext)
 File "c:\Python27\lib\distutils\command\build_ext.py", line 496, in build_extension
 depends=ext.depends)
 File "c:\Python27\lib\distutils\msvc9compiler.py", line 475, in compile
 self.initialize()
 File "c:\Python27\lib\distutils\msvc9compiler.py", line 385, in initialize
 vc_env = query_vcvarsall(VERSION, plat_spec)
 File "c:\Python27\lib\distutils\msvc9compiler.py", line 301, in query_vcvarsall
 raise ValueError(str(list(result.keys())))
 ValueError: [u'path']

It appears that the function “query_vcvarsall” fails if it doesn’t find a set of 4 environment variables (this is some dodgy coding to me :p):

  • path
  • include
  • lib
  • libpath

You may need to create these environment variables, and place in them the appropriate paths for your PC.

On my 64-bit windows 8 machine with 64-bit Python 2.7.6, I have the following:

LIB = C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\ATLMFC\LIB;C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\LIB;%WindowsSdkDir%lib;C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1A\Lib;C:\Python27\Lib;%LIB%
INCLUDE = C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\ATLMFC\INCLUDE;C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\INCLUDE;%WindowsSdkDir%include;C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1A\Include;C:\Python27\include;%INCLUDE%
PATH = C:\Program Files (x86)\Microsoft Visual Studio 9.0\Common7\IDE;C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\BIN;C:\Program Files (x86)\Microsoft Visual Studio 9.0\Common7\Tools;C:\WINDOWS\Microsoft.NET\Framework\v3.5;C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727;C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\VCPackages;%WindowsSdkDir%bin;C:\Python27\Scripts;C:\Python27;%PATH%
LIBPATH = C:\WINDOWS\Microsoft.NET\Framework\v3.5;C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727;C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\ATLMFC\LIB;C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\LIB;C:\Python27\Lib;C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1A\Lib;%LIBPATH%

After that, I am able to use pip to install pycrypto.

Note that my variables may contain paths which are redundant, but I arrived there after a windy path of experimentation. After It worked, I said to myself: “if it ain’t broke, don’t fix it.”

The following site was very helpful in showing me alternative ways. I like what the guy did to the python utility scripts. Just hack them to do what I want. None of the cruft of general-purpose code. Just tell the bloody system I have Visual Studio 9.0 😉 http://blog.victorjabur.com/2011/06/05/compiling-python-2-7-modules-on-windows-32-and-64-using-msvc-2008-express/

 

 

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Windows 8 SSD 100% disk usage

Upgraded my Windows 8.1 PC by installing a 240GB Crucial SSD, and the performance became worse than with a spinning disk.

In my instance, I was able to improve the experience simply by installing Intel Rapid Storage tools drivers (downloaded from MSI’s site for my specific motherboard). I accepted all defaults. I was using an MSI motherboard. This just might be your solution.

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Openssl Hint for today

You find yourself trying to look at a certificate with Openssl (I’m using the cygwin version of openssl on windows 7):

$ openssl.exe x509 -in certificate.crt -text
unable to load certificate
2675716:error:0906D06C:PEM routines:PEM_read_bio:no start line:pem_lib.c:703:Expecting: TRUSTED CERTIFICATE

Openssl error messages are so cryptic, I tried looking at the code to deduce what it meant, and even that didn’t go so well.

The error message shown above doesn’t really have much to do with “trust”. It most likely means that your certificate is not in PEM format. The most common other format that certificates can be in is DER. If you wanted to view the certificate in DER format anyway, you would do this:

$ openssl.exe x509 -inform DER -in certificate.crt -text

the -inform argument allows you to specify what format the certificate you are trying to examine is in. The -text argument says “display it on screen”, and the -in argument specifies the certificate file name.

If you wanted to convert that certificate from DER to PEM, you would say:

$ openssl.exe x509 -inform DER -outform PEM -out ./PEMcert.crt -in DERcert.crt

-outform PEM says the output format should be PEM, and the -out argument specifies the filename to give the converted certificate.

 

 

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Jquery .load() makes the target blank

If you run into the problem where calling .load(url) on an element makes it turn blank, you very likely have an unexpected space (” “) in your url.

You should re-examine it, it may be a trailing or leading space, which will make it difficult to see with the naked eye. Try calling the javscript .trim() on the url string.

At the time of this writing, I was using version 1.10.2.

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