Installing Arachni from Source on Ubuntu 11.04 (Natty)

Herman Stevens has developed an XSLT for importing Arachni data into MagicTree.

To test his XSLT I went to install the latest development version of Arachni on my Ubuntu 11.04 (natty). Having fought with it for a while and finally managing to install it, I thought that the description of the process might help somebody else. So here it goes.

First I downloaded the sources:
*alla@notsoshiny:~$ sudo apt-get install libxml2-dev libxslt1-dev libcurl4-openssl-dev libsqlite3-dev
alla@notsoshiny:~$ git clone git://github.com/Zapotek/arachni.git
alla@notsoshiny:~$ cd arachni
alla@notsoshiny:~/arachni$ rake install*
“Rake install” failed because I didn’t have rake installed. So, I installed rake:
*alla@notsoshiny:~$ sudo apt-get install rake*
And tried “rake install” again:

alla@notsoshiny:~/arachni$ rake install
(in /home/alla/arachni)
rm *.afr || true
rm: cannot remove `*.afr': No such file or directory
rm *.yaml || true
rm: cannot remove `*.yaml': No such file or directory
rm *.json || true
rm: cannot remove `*.json': No such file or directory
rm *.marshal || true
rm: cannot remove `*.marshal': No such file or directory
rm *.gem || true
rm: cannot remove `*.gem': No such file or directory
rm logs/*.log || true
rm: cannot remove `logs/*.log': No such file or directory
rm lib/arachni/ui/web/server/db/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/db/*.*': No such file or directory
rm lib/arachni/ui/web/server/db/welcomed || true
rm: cannot remove `lib/arachni/ui/web/server/db/welcomed': No such file or directory
rm lib/arachni/ui/web/server/public/reports/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/public/reports/*.*': No such file or directory
rm lib/arachni/ui/web/server/tmp/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/tmp/*.*': No such file or directory
gem build arachni.gemspec
rake aborted!
Command failed with status (127): [gem build arachni.gemspec...]
/home/alla/arachni/Rakefile:76
(See full trace by running task with --trace)\

Some googling enlightened me that exit code 127 means “file not found”, so I deduced that “gem” is missing. Installed gem:

alla@notsoshiny:~/arachni$ sudo apt-get install rubygems1.8\

And tried rake install again:

alla@notsoshiny:~/arachni$ rake install --trace
(in /home/alla/arachni)
** Invoke install (first_time)
** Invoke build (first_time)
** Invoke clean (first_time)
** Execute clean
rm *.afr || true
rm: cannot remove `*.afr': No such file or directory
rm *.yaml || true
rm: cannot remove `*.yaml': No such file or directory
rm *.json || true
rm: cannot remove `*.json': No such file or directory
rm *.marshal || true
rm: cannot remove `*.marshal': No such file or directory
rm *.gem || true
rm: cannot remove `*.gem': No such file or directory
rm logs/*.log || true
rm: cannot remove `logs/*.log': No such file or directory
rm lib/arachni/ui/web/server/db/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/db/*.*': No such file or directory
rm lib/arachni/ui/web/server/db/welcomed || true
rm: cannot remove `lib/arachni/ui/web/server/db/welcomed': No such file or directory
rm lib/arachni/ui/web/server/public/reports/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/public/reports/*.*': No such file or directory
rm lib/arachni/ui/web/server/tmp/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/tmp/*.*': No such file or directory
** Execute build
gem build arachni.gemspec
WARNING: no rubyforge_project specified
Successfully built RubyGem
Name: arachni
Version: 0.4.0.2
File: arachni-0.4.0.2.gem
** Execute install
gem install arachni-0.4.0.2.gem
ERROR: While executing gem ... (Gem::FilePermissionError)
You don't have write permissions into the /var/lib/gems/1.8 directory.
rake aborted!
Command failed with status (1): [gem install arachni-0.4.0.2.gem...]
/usr/lib/ruby/1.8/rake.rb:995:in `sh'
/usr/lib/ruby/1.8/rake.rb:1010:in `call'
/usr/lib/ruby/1.8/rake.rb:1010:in `sh'
/usr/lib/ruby/1.8/rake.rb:1094:in `sh'
/home/alla/arachni/Rakefile:85
/usr/lib/ruby/1.8/rake.rb:636:in `call'
/usr/lib/ruby/1.8/rake.rb:636:in `execute'
/usr/lib/ruby/1.8/rake.rb:631:in `each'
/usr/lib/ruby/1.8/rake.rb:631:in `execute'
/usr/lib/ruby/1.8/rake.rb:597:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/usr/lib/ruby/1.8/rake.rb:590:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/rake.rb:583:in `invoke'
/usr/lib/ruby/1.8/rake.rb:2051:in `invoke_task'
/usr/lib/ruby/1.8/rake.rb:2029:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2029:in `each'
/usr/lib/ruby/1.8/rake.rb:2029:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:2023:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2001:in `run'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:1998:in `run'
/usr/bin/rake:28\

Okay, that one is easy, just need to do “sudo rake install”:

alla@notsoshiny:~/arachni$ sudo rake install --trace
(in /home/alla/arachni)
** Invoke install (first_time)
** Invoke build (first_time)
** Invoke clean (first_time)
** Execute clean
rm *.afr || true
rm: cannot remove `*.afr': No such file or directory
rm *.yaml || true
rm: cannot remove `*.yaml': No such file or directory
rm *.json || true
rm: cannot remove `*.json': No such file or directory
rm *.marshal || true
rm: cannot remove `*.marshal': No such file or directory
rm *.gem || true
rm logs/*.log || true
rm: cannot remove `logs/*.log': No such file or directory
rm lib/arachni/ui/web/server/db/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/db/*.*': No such file or directory
rm lib/arachni/ui/web/server/db/welcomed || true
rm: cannot remove `lib/arachni/ui/web/server/db/welcomed': No such file or directory
rm lib/arachni/ui/web/server/public/reports/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/public/reports/*.*': No such file or directory
rm lib/arachni/ui/web/server/tmp/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/tmp/*.*': No such file or directory
** Execute build
gem build arachni.gemspec
WARNING: no rubyforge_project specified
Successfully built RubyGem
Name: arachni
Version: 0.4.0.2
File: arachni-0.4.0.2.gem
** Execute install
gem install arachni-0.4.0.2.gem
Building native extensions. This could take a while...
Building native extensions. This could take a while...
Building native extensions. This could take a while...
Building native extensions. This could take a while...
Building native extensions. This could take a while...
ERROR: Error installing arachni-0.4.0.2.gem:
dm-serializer requires json (~> 1.4.6, runtime)
rake aborted!
Command failed with status (1): [gem install arachni-0.4.0.2.gem...]
/usr/lib/ruby/1.8/rake.rb:995:in `sh'
/usr/lib/ruby/1.8/rake.rb:1010:in `call'
/usr/lib/ruby/1.8/rake.rb:1010:in `sh'
/usr/lib/ruby/1.8/rake.rb:1094:in `sh'
/home/alla/arachni/Rakefile:85
/usr/lib/ruby/1.8/rake.rb:636:in `call'
/usr/lib/ruby/1.8/rake.rb:636:in `execute'
/usr/lib/ruby/1.8/rake.rb:631:in `each'
/usr/lib/ruby/1.8/rake.rb:631:in `execute'
/usr/lib/ruby/1.8/rake.rb:597:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/usr/lib/ruby/1.8/rake.rb:590:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/rake.rb:583:in `invoke'
/usr/lib/ruby/1.8/rake.rb:2051:in `invoke_task'
/usr/lib/ruby/1.8/rake.rb:2029:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2029:in `each'
/usr/lib/ruby/1.8/rake.rb:2029:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:2023:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2001:in `run'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:1998:in `run'
/usr/bin/rake:28\

Okay, so json is missing, I guess I need to install it:

alla@notsoshiny:~/arachni$ sudo gem install json
Building native extensions. This could take a while...
Successfully installed json-1.6.5
1 gem installed
Installing ri documentation for json-1.6.5...
Installing RDoc documentation for json-1.6.5...\

And once again “rake install”:

alla@notsoshiny:~/arachni$ sudo rake install --trace
(in /home/alla/arachni)
** Invoke install (first_time)
** Invoke build (first_time)
** Invoke clean (first_time)
** Execute clean
rm *.afr || true
rm: cannot remove `*.afr': No such file or directory
rm *.yaml || true
rm: cannot remove `*.yaml': No such file or directory
rm *.json || true
rm: cannot remove `*.json': No such file or directory
rm *.marshal || true
rm: cannot remove `*.marshal': No such file or directory
rm *.gem || true
rm logs/*.log || true
rm: cannot remove `logs/*.log': No such file or directory
rm lib/arachni/ui/web/server/db/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/db/*.*': No such file or directory
rm lib/arachni/ui/web/server/db/welcomed || true
rm: cannot remove `lib/arachni/ui/web/server/db/welcomed': No such file or directory
rm lib/arachni/ui/web/server/public/reports/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/public/reports/*.*': No such file or directory
rm lib/arachni/ui/web/server/tmp/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/tmp/*.*': No such file or directory
** Execute build
gem build arachni.gemspec
WARNING: no rubyforge_project specified
Successfully built RubyGem
Name: arachni
Version: 0.4.0.2
File: arachni-0.4.0.2.gem
** Execute install
gem install arachni-0.4.0.2.gem
ERROR: Error installing arachni-0.4.0.2.gem:
dm-serializer requires json (~> 1.4.6, runtime)
rake aborted!
Command failed with status (1): [gem install arachni-0.4.0.2.gem...]
/usr/lib/ruby/1.8/rake.rb:995:in `sh'
/usr/lib/ruby/1.8/rake.rb:1010:in `call'
/usr/lib/ruby/1.8/rake.rb:1010:in `sh'
/usr/lib/ruby/1.8/rake.rb:1094:in `sh'
/home/alla/arachni/Rakefile:85
/usr/lib/ruby/1.8/rake.rb:636:in `call'
/usr/lib/ruby/1.8/rake.rb:636:in `execute'
/usr/lib/ruby/1.8/rake.rb:631:in `each'
/usr/lib/ruby/1.8/rake.rb:631:in `execute'
/usr/lib/ruby/1.8/rake.rb:597:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/usr/lib/ruby/1.8/rake.rb:590:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/rake.rb:583:in `invoke'
/usr/lib/ruby/1.8/rake.rb:2051:in `invoke_task'
/usr/lib/ruby/1.8/rake.rb:2029:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2029:in `each'
/usr/lib/ruby/1.8/rake.rb:2029:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:2023:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2001:in `run'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:1998:in `run'
/usr/bin/rake:28\

Installing json did not help? Googling revealed a tweet by @h4x0rcouk and a reply from @Zap0tek suggesting to install json version 1.4.6. So:
alla@notsoshiny:~/arachni$ sudo gem uninstall json
You have requested to uninstall the gem:
json-1.6.5
typhoeus-0.3.3 depends on [json (>= 0)]
dm-serializer-1.2.1 depends on [json (~> 1.6.1)]
If you remove this gems, one or more dependencies will not be met.
Continue with Uninstall? [Yn]
Successfully uninstalled json-1.6.5
alla@notsoshiny:~/arachni$ sudo gem install json -v 1.4.6
Building native extensions. This could take a while...
Successfully installed json-1.4.6
1 gem installed
Installing ri documentation for json-1.4.6...
Installing RDoc documentation for json-1.4.6...
alla@notsoshiny:~/arachni$ sudo gem uninstall dm-serializer
Successfully uninstalled dm-serializer-1.2.1

And rake install once again:

alla@notsoshiny:~/arachni$ sudo rake install --trace
(in /home/alla/arachni)
** Invoke install (first_time)
** Invoke build (first_time)
** Invoke clean (first_time)
** Execute clean
rm *.afr || true
rm: cannot remove `*.afr': No such file or directory
rm *.yaml || true
rm: cannot remove `*.yaml': No such file or directory
rm *.json || true
rm: cannot remove `*.json': No such file or directory
rm *.marshal || true
rm: cannot remove `*.marshal': No such file or directory
rm *.gem || true
rm logs/*.log || true
rm: cannot remove `logs/*.log': No such file or directory
rm lib/arachni/ui/web/server/db/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/db/*.*': No such file or directory
rm lib/arachni/ui/web/server/db/welcomed || true
rm: cannot remove `lib/arachni/ui/web/server/db/welcomed': No such file or directory
rm lib/arachni/ui/web/server/public/reports/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/public/reports/*.*': No such file or directory
rm lib/arachni/ui/web/server/tmp/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/tmp/*.*': No such file or directory
** Execute build
gem build arachni.gemspec
WARNING: no rubyforge_project specified
Successfully built RubyGem
Name: arachni
Version: 0.4.0.2
File: arachni-0.4.0.2.gem
** Execute install
gem install arachni-0.4.0.2.gem
Building native extensions. This could take a while...
Building native extensions. This could take a while...
ERROR: While executing gem ... (NoMethodError)
undefined method `call' for nil:NilClass
rake aborted!
Command failed with status (1): [gem install arachni-0.4.0.2.gem...]
/usr/lib/ruby/1.8/rake.rb:995:in `sh'
/usr/lib/ruby/1.8/rake.rb:1010:in `call'
/usr/lib/ruby/1.8/rake.rb:1010:in `sh'
/usr/lib/ruby/1.8/rake.rb:1094:in `sh'
/home/alla/arachni/Rakefile:85
/usr/lib/ruby/1.8/rake.rb:636:in `call'
/usr/lib/ruby/1.8/rake.rb:636:in `execute'
/usr/lib/ruby/1.8/rake.rb:631:in `each'
/usr/lib/ruby/1.8/rake.rb:631:in `execute'
/usr/lib/ruby/1.8/rake.rb:597:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/usr/lib/ruby/1.8/rake.rb:590:in `invoke_with_call_chain'
/usr/lib/ruby/1.8/rake.rb:583:in `invoke'
/usr/lib/ruby/1.8/rake.rb:2051:in `invoke_task'
/usr/lib/ruby/1.8/rake.rb:2029:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2029:in `each'
/usr/lib/ruby/1.8/rake.rb:2029:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:2023:in `top_level'
/usr/lib/ruby/1.8/rake.rb:2001:in `run'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:1998:in `run'
/usr/bin/rake:28

Undefined method `call’ for nil:NilClass gives lots of results on Goolge none of them particularly helpful. I figured out this probably has something to do with amissing dependency. So, I looke through arachni.gemspec file and checked if all dependencies listed there are present by doing “gem query –local” and grepping for each one of them. Turns out everything is present except “arachni-rpc-em”

So, now I need to install arachni-rpc-em:

alla@notsoshiny:~$ git clone https://github.com/Arachni/arachni-rpc-em.git
alla@notsoshiny:~$ cd arachni-rpc-em/
alla@notsoshiny:~/arachni-rpc-em$ sudo rake install
(in /home/alla/arachni-rpc-em)
rake aborted!
no such file to load -- rspec
/home/alla/arachni-rpc-em/Rakefile:10
(See full trace by running task with --trace)
alla@notsoshiny:~/arachni-rpc-em$ less README.md
alla@notsoshiny:~/arachni-rpc-em$ sudo rake install --trace
(in /home/alla/arachni-rpc-em)
rake aborted!
no such file to load -- rspec
/usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
/usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require'
/home/alla/arachni-rpc-em/Rakefile:10
/usr/lib/ruby/1.8/rake.rb:2383:in `load'
/usr/lib/ruby/1.8/rake.rb:2383:in `raw_load_rakefile'
/usr/lib/ruby/1.8/rake.rb:2017:in `load_rakefile'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:2016:in `load_rakefile'
/usr/lib/ruby/1.8/rake.rb:2000:in `run'
/usr/lib/ruby/1.8/rake.rb:2068:in `standard_exception_handling'
/usr/lib/ruby/1.8/rake.rb:1998:in `run'
/usr/bin/rake:28

Looks like we need rspec, whatever that is:

alla@notsoshiny:~/arachni-rpc-em$ sudo gem install rspec
Successfully installed rspec-core-2.8.0
Successfully installed diff-lcs-1.1.3
Successfully installed rspec-expectations-2.8.0
Successfully installed rspec-mocks-2.8.0
Successfully installed rspec-2.8.0
5 gems installed
Installing ri documentation for rspec-core-2.8.0...
Installing ri documentation for diff-lcs-1.1.3...
Installing ri documentation for rspec-expectations-2.8.0...
Installing ri documentation for rspec-mocks-2.8.0...
Installing ri documentation for rspec-2.8.0...
Installing RDoc documentation for rspec-core-2.8.0...
Installing RDoc documentation for diff-lcs-1.1.3...
Installing RDoc documentation for rspec-expectations-2.8.0...
Installing RDoc documentation for rspec-mocks-2.8.0...
Installing RDoc documentation for rspec-2.8.0...

Okay, rake install once again:

alla@notsoshiny:~/arachni-rpc-em$ sudo rake install --trace
(in /home/alla/arachni-rpc-em)
** Invoke install (first_time)
** Invoke build (first_time)
** Invoke clean (first_time)
** Execute clean
rm *.gem || true
rm: cannot remove `*.gem': No such file or directory
** Execute build
gem build arachni-rpc-em.gemspec
WARNING: no rubyforge_project specified
Successfully built RubyGem
Name: arachni-rpc-em
Version: 0.1.1
File: arachni-rpc-em-0.1.1.gem
** Execute install
gem install arachni-rpc-em-0.1.1.gem
Successfully installed arachni-rpc-em-0.1.1
1 gem installed
Installing ri documentation for arachni-rpc-em-0.1.1...
Installing RDoc documentation for arachni-rpc-em-0.1.1...

And going back to arachni itself and trying rake install once again:

alla@notsoshiny:~/arachni-rpc-em$ cd ../arachni
alla@notsoshiny:~/arachni$ sudo rake install --trace
[sudo] password for alla:
(in /home/alla/arachni)
** Invoke install (first_time)
** Invoke build (first_time)
** Invoke clean (first_time)
** Execute clean
rm *.afr || true
rm: cannot remove `*.afr': No such file or directory
rm *.yaml || true
rm: cannot remove `*.yaml': No such file or directory
rm *.json || true
rm: cannot remove `*.json': No such file or directory
rm *.marshal || true
rm: cannot remove `*.marshal': No such file or directory
rm *.gem || true
rm logs/*.log || true
rm: cannot remove `logs/*.log': No such file or directory
rm lib/arachni/ui/web/server/db/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/db/*.*': No such file or directory
rm lib/arachni/ui/web/server/db/welcomed || true
rm: cannot remove `lib/arachni/ui/web/server/db/welcomed': No such file or directory
rm lib/arachni/ui/web/server/public/reports/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/public/reports/*.*': No such file or directory
rm lib/arachni/ui/web/server/tmp/*.* || true
rm: cannot remove `lib/arachni/ui/web/server/tmp/*.*': No such file or directory
** Execute build
gem build arachni.gemspec
WARNING: no rubyforge_project specified
Successfully built RubyGem
Name: arachni
Version: 0.4.0.2
File: arachni-0.4.0.2.gem
** Execute install
gem install arachni-0.4.0.2.gem
Successfully installed arachni-0.4.0.2
1 gem installed
Installing ri documentation for arachni-0.4.0.2...
Installing RDoc documentation for arachni-0.4.0.2...

Success! Hardly took an hour. So now let’s try to run it:

alla@notsoshiny:~/arachni/bin$ ./arachni_web_autostart
[>] Starting the Arachni Dispatch server...
[>] Starting the Arachni WebUI server...
[>] Opening browser...
[>] Hit Ctrl+C to shut everything down.
^C\

Nothing is listening on port 4567. I am going to try to start arachni_rpcd manually:

alla@notsoshiny:~/arachni/bin$ ./arachni_rpcd
./arachni_rpcd:12: undefined method `require_relative' for main:Object (NoMethodError)\

Perhaps the command-line interface will work?

alla@notsoshiny:~/arachni/bin$ ./arachni
./arachni:12: undefined method `require_relative' for main:Object (NoMethodError)\

Nope. More googling finds a post on StackOverflow “Why doesn’t relative_require work on Ruby 1.8.6?” It suggests installing ruby extensions and adding “require ’extensions/all’” before “require_relative”.

alla@notsoshiny:~$ sudo gem install extensions
*Successfully installed extensions-0.6.0
1 gem installed
Installing ri documentation for extensions-0.6.0...
Installing RDoc documentation for extensions-0.6.0...
alla@notsoshiny:~$ cd arachni
alla@notsoshiny:~/arachni$ cd bin/
alla@notsoshiny:~/arachni/bin$ ls
arachni arachni_rpc arachni_rpcd arachni_rpcd_monitor arachni_web arachni_web_autostart
alla@notsoshiny:~/arachni/bin$ ./arachni
./arachni:12: undefined method `require_relative' for main:Object (NoMethodError)*
Now edit arachni adding the line “require ’extensions/all’” before “require_relative”.

alla@notsoshiny:~/arachni/bin$ vi arachni
alla@notsoshiny:~/arachni/bin$ ./arachni
./arachni:12:in `require': no such file to load -- extensions/all (LoadError)
from ./arachni:12

Ok, this didn’t help. I’ve read the StackOverflow thread a bit more and figured that I probably have an old version of Ruby:

alla@notsoshiny:~/arachni/bin$ ruby --version
ruby 1.8.7 (2010-08-16 patchlevel 302) [i686-linux]

So, I installed a newer version of Ruby:
*
alla@notsoshiny:~/arachni/bin$ sudo apt-get install ruby1.9.1*
And ran Arachni with ruby 1.9.1:
alla@notsoshiny:~/arachni/bin$ /usr/bin/ruby1.9.1 arachni
<internal:lib/rubygems/custom_require>:29:in `require': no such file to load -- ap (LoadError)
from :29:in `require'
from /home/alla/arachni/lib/arachni/framework.rb:11:in `<top (required)>'
from /home/alla/arachni/lib/arachni.rb:11:in `require_relative'
from /home/alla/arachni/lib/arachni.rb:11:in `<top (required)>'
from :29:in `require'
from :29:in `require'
from /home/alla/arachni/lib/arachni/ui/cli/cli.rb:17:in `<module:Arachni>'
from /home/alla/arachni/lib/arachni/ui/cli/cli.rb:12:in `<top (required)>'
from :29:in `require'
from :29:in `require'
from arachni:16:in `<main>'\

TO BE CONTINUED