For content and media, there are the Creative Commons licenses, some of which make it possible for creators to provide their work for free, while at the same time they still reserve the right to selectively make their work available for commercial purposes under different terms. That’s the beauty of those licenses. They are made to solve real problems and that’s why I highly respect them.

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• Save pages to a reading list to read when you have time.
• Offline reading mode lets you read the items you’ve saved for later on the plane, train, or anywhere without an internet connection.
• Sync your list to all of your computers, at work or home.
• Sync your list to Read It Later apps for iPhone, iPod, iPad, Android and more.
• After reading, bookmark pages on your preferred bookmarking service or share them with friends.
• Click to Save Mode lets you quickly batch a reading list just by clicking on interesting links.
• Text view strips away images, ads, and layout from articles and presents them in an easy to consume way.

Until today I have been keeping content that I wished to read at a later time in the browser’s bookmark system or I left yet another tab open or stored the URL in a text file. This plugin seems that it will provide a decent solution and eliminate the trouble. I haven’t used the remote service yet and I am not sure if I will ever do. The local “read queue” works really well.

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I removed the following items from the HTML HEAD:

• Link to the Really Simple Discovery service endpoint. That’s the link to: /xmlrpc.php?rsd
• Link to the first post on your blog.
• Link to the Windows Live Writer manifest file. That’s the link to: /wp-includes/wlwmanifest.xml
• The generator meta tag.
• The shortlink.

From the “feeds” section I removed the the “generator” element.

Finally, from the HTTP headers section I removed everything. In my case, the ETag, Expires and Cache-Control headers are added by the webserver (FileETags and mod_expires). If this is not the case for you, then consider keeping these enabled.

Another thing you should keep in mind is that if you use any caching mechanism, like WP-Super-Cache, make sure you clear the cache after you make any changes in the WP-Clutter’s administration panel, otherwise the changes you made will be visible after the cached pages expire.

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• Automated extraction of the version and configuration of BusyBox
• Extraction of file systems
• Automated checking for the Linux kernel
• Brute force scanning of firmware
• Feeding known information through a knowledgebase

This means that, currently, it can detect the kernel and busybox in the firmware of electronic devices. I have no clue about its effectiveness and, possibly, I won’t be trying it any time soon, but, if you are interested, make sure you read more information about the features of the Binary Analysis Tool and check out the code.

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But first, let’s install some dependencies. I assume that you will try the code on a machine aimed for testing, so I won’t be using the system’s package manager but instead use easy_install to install the needed Python modules. Other commands like pip could be used as well. If you do not want to mess with your system-wide python installation, just use virtualenv and pip, but I won’t go into the details about how to use these tools in the current document.

Install the needed dependencies:

easy_install pycrypto
easy_install pyasn1
easy_install pam
easy_install twisted

Make sure you have gcc installed, because it will be needed to complete the installation of Twisted and PyCrypto.

I have created a project for this code at Bitbucket, called RapidSSH. This will make it easier to share code and ideas about SSH server implementations in Python using Twisted.

Filename: scripts/rapidsshd_unix.py

#!/usr/bin/env python
#
# This file is part of rapidssh - http://bitbucket.org/gnotaras/rapidssh/
#
# rapidssh - A set of Secure Shell (SSH) server implementations in Python
#            using Twisted.conch, part of the Twisted Framework.
#
# Copyright (c) 2010 George Notaras - http://www.g-loaded.eu
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
# Initially based on the sshsimpleserver.py kindly published by:
# Twisted Matrix Laboratories - http://twistedmatrix.com
#
 
import sys
import pam
 
from twisted.conch.unix import UnixSSHRealm
from twisted.cred import portal
from twisted.cred.credentials import IUsernamePassword
from twisted.cred.checkers import ICredentialsChecker
from twisted.cred.error import UnauthorizedLogin
from twisted.conch.checkers import SSHPublicKeyDatabase
from twisted.conch.ssh import factory, userauth, connection, keys, session
from twisted.internet import reactor, defer
from zope.interface import implements
from twisted.python import log
 
# Logging
# Currently logging to STDERR
log.startLogging(sys.stderr)
 
# Server-side public and private keys. These are the keys found in
# sshsimpleserver.py. Make sure you generate your own using ssh-keygen!
 
publicKey = 'ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAGEArzJx8OYOnJmzf4tfBEvLi8DVPrJ3/c9k2I/Az64fxjHf9imyRJbixtQhlH9lfNjUIx+4LmrJH5QNRsFporcHDKOTwTTYLh5KmRpslkYHRivcJSkbh/C+BR3utDS555mV'
 
privateKey = """-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----"""
 
 
class PamPasswordDatabase:
    """Authentication/authorization backend using the 'login' PAM service"""
    credentialInterfaces = IUsernamePassword,
    implements(ICredentialsChecker)
 
    def requestAvatarId(self, credentials):
        if pam.authenticate(credentials.username, credentials.password):
            return defer.succeed(credentials.username)
        return defer.fail(UnauthorizedLogin("invalid password"))
 
 
class UnixSSHdFactory(factory.SSHFactory):
    publicKeys = {
        'ssh-rsa': keys.Key.fromString(data=publicKey)
    }
    privateKeys = {
        'ssh-rsa': keys.Key.fromString(data=privateKey)
    }
    services = {
        'ssh-userauth': userauth.SSHUserAuthServer,
        'ssh-connection': connection.SSHConnection
    }
 
# Components have already been registered in twisted.conch.unix
 
portal = portal.Portal(UnixSSHRealm())
portal.registerChecker(PamPasswordDatabase())   # Supports PAM
portal.registerChecker(SSHPublicKeyDatabase())  # Supports PKI
UnixSSHdFactory.portal = portal
 
if __name__ == '__main__':
    reactor.listenTCP(5022, UnixSSHdFactory())
    reactor.run()

Some notes:

• The server uses the very same public and private keys as found in the sshsimpleserver.py script. Make sure you generate new keys using ssh-keygen if you plan to run this on a public server (although this not recommended).
• Twisted included a module for PAM authentication, twisted.cred.pamauth, but unfortunately I could not locate one of its dependencies to make it work. So, I used the excellent python-pam to create a custom PAM authenticator class.
• I can guess what you might thought when you read about this code:
  

  Python is a cross-platform programming language. Twisted runs on Windows. So, is this a solution for running a SSH server on Win32?

  Well, at the moment it won’t run because internally it uses some Python modules that are available on UNIX platforms only. But, I intend to investigate the possibility of running this on Windows since I already need something like that.

We can now enjoy our Python SSH server. Run as root:

python scripts/rapidsshd_unix.py

From another machine, connect to the server using an ssh client:

ssh -p 5022 rocky@arena

If you have deployed your public key in the ~/.ssh/authorized_keys file on the remote machine (arena), you should be able to authenticate using the public key:

ssh -p 5022 -i /path/to/private.key rocky@arena

You should get output like the following on the server:

[root@arena ~]# python ssh.py
2010-03-26 21:30:05+0000 [-] Log opened.
2010-03-26 21:30:05+0000 [-] __main__.UnixSSHdFactory starting on 5022
2010-03-26 21:30:05+0000 [-] Starting factory <__main__.UnixSSHdFactory instance at 0xb7a0b0cc>
2010-03-26 21:30:13+0000 [__main__.UnixSSHdFactory] disabling diffie-hellman-group-exchange because we cannot find moduli file
2010-03-26 21:30:13+0000 [SSHServerTransport,0,192.168.0.172] kex alg, key alg: diffie-hellman-group1-sha1 ssh-rsa
2010-03-26 21:30:13+0000 [SSHServerTransport,0,192.168.0.172] outgoing: aes256-ctr hmac-sha1 none
2010-03-26 21:30:13+0000 [SSHServerTransport,0,192.168.0.172] incoming: aes256-ctr hmac-sha1 none
2010-03-26 21:30:14+0000 [SSHServerTransport,0,192.168.0.172] NEW KEYS
2010-03-26 21:30:14+0000 [SSHServerTransport,0,192.168.0.172] starting service ssh-userauth
2010-03-26 21:30:17+0000 [SSHService ssh-userauth on SSHServerTransport,0,192.168.0.172] rocky trying auth none
2010-03-26 21:30:17+0000 [SSHService ssh-userauth on SSHServerTransport,0,192.168.0.172] rocky trying auth publickey
2010-03-26 21:30:17+0000 [SSHService ssh-userauth on SSHServerTransport,0,192.168.0.172] rocky trying auth publickey
2010-03-26 21:30:17+0000 [SSHService ssh-userauth on SSHServerTransport,0,192.168.0.172] rocky authenticated with publickey
2010-03-26 21:30:17+0000 [SSHService ssh-userauth on SSHServerTransport,0,192.168.0.172] starting service ssh-connection
2010-03-26 21:30:17+0000 [SSHService ssh-connection on SSHServerTransport,0,192.168.0.172] got channel session request
2010-03-26 21:30:17+0000 [SSHChannel session (0) on SSHService ssh-connection on SSHServerTransport,0,192.168.0.172] channel open
2010-03-26 21:30:17+0000 [SSHChannel session (0) on SSHService ssh-connection on SSHServerTransport,0,192.168.0.172] pty request: xterm (24L, 80L, 0L, 0L)
2010-03-26 21:30:17+0000 [SSHChannel session (0) on SSHService ssh-connection on SSHServerTransport,0,192.168.0.172] getting shell

This first release of the RapidSSH project exists solely for demonstration purposes. Don’t get fooled by the small amount of code. Information about how to put the pieces together is scarce and it required a lot trial&error and source code reading. The above implementation contains none of the customizations I had in mind. These will be done as soon as I find some time to do so. Until then it will be nice to hear about your experiences or implementations you have worked on.

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1. security
2. reliability
3. backwards compatibility
4. extensibility

A few years ago, I had published an approach on how to organize mailing list messages using Evolution. The same tips and tricks apply to Thunderbird, so those of you who deal with many mailing lists might find that old article interesting.

The highlights of the new release include:

• Tabbed Email: Provides the ability view individual emails and folders in tabs.
• Filtered Search: The new search interface contains filtering and timeline tools
• Message Archive: When an email message is archived, it is moved from the inbox into the new archive folder system, de-cluttering the inbox, while, at the same time, enabling users to find email months or years from now.
• One-click Address Book: A very quick and easy way to add people to an address book, by simply clicking on the star icon in the messages received from new correspondents.
• New Mail Account Setup Wizard: Getting started with Thunderbird 3 is faster than ever with the new account set-up wizard that requires simple information, like email addresses and passwords to get going instead of a user’s IMAP, SMTP, SSL/TLS settings.
• Smart Folders: Combines individual mailboxes to help manage multiple email accounts in one spot. For example, by selecting the Inbox, users can view all the incoming emails from all their different accounts without having to go to each email account separately.
• Add-ons Manager: The new add-ons manager can help users find, download, and install hundreds of add-ons enabling them to customize Thunderbird 3 and add functionality or change the appearance.
• Gecko 1.9.1 Engine: The same Web page rendering engine and graphics infrastructure used in Firefox, provides the latest Web Standards support and security enhancements.
• Automated Updates: Thunderbird’s update system notifies users when a security update is available and automates the download and installation process to keep users safe.

Now, I am off to test this beast’s new features…

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shred: change default number of overwrites from 25 to 3
* src/shred.c: The concensus is that a default of 3
passes is appropriate for current drive technologies.
* src/TODO: Reference Paul Eggert's suggestion
of enhancing shred to conform to DoD 5220 rules.

I would like to publicly thank Pádraig for the feedback. There are times that the open source development model takes me by surprise.

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Note: in a previous post I had tried to implement a shutdown/reboot/suspend prevention switch using various inefficient methods. After receiving some pointers from members of the Linux-Greek-Users mailing list, I studied the initscript mechanism and wrote this solution. It has been tested on Fedora only and is released for Fedora and RedHat based linux distributions. I would appreciate feedback about its compatibility with Debian or Gentoo based systems.

Manual Installation

As user ‘root‘ follow the instructions to install the file in your initscripts directory:

cp delayed-shutdown /etc/init.d/
chmod +x /etc/init.d/delayed-shutdown

For RedHat and relatives run:

chkconfig --add delayed-shutdown

For Debian and relatives run:

update-rc.d delayed-shutdown defaults

Manual De-installation

If for any reason you need to remove ‘delayed-shutdown’ from your system do the following:

For RedHat and relatives run:

chkconfig --del delayed-shutdown

For Debian and relatives run:

update-rc.d -f delayed-shutdown remove

Delete the initscript:

rm /etc/init.d/delayed-shutdown

Usage

In order to delay the shutdown process until your software finishes its operation, you should create the no-shutdown lock file:

/var/lock/noshutdown.lock

Then let your software do its job and, when finished, delete the no-shutdown lock file. In case of a script that would be:

lockfile /var/lock/noshutdown.lock
... [script is working] ...
rm -f /var/lock/noshutdown.lock

Test

A test script, test.sh, is included in the distribution package. In order perform a test, do the following:

• Make sure you have installed the delayed-shutdown initscript as described in the “installation section.
• Run test.sh: ./test.sh &
• Reboot or shutdown the machine

Test.sh will acquire the lock, sleep in the background for 90 seconds and then release the lock. The shutdown/reboot procedure will continue after the lock has been released.

Download

All versions of the software, including the latest stable release, are available from the development web site’s download area.

Misc

The initscript delayed-shutdown is released under the terms of the MIT license.

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Taking these things into consideration, I decided to write Fast-Static-Feed, a plugin that can cache the site’s entries feed, and deliver a static XML file instead of constantly generating the feed content on every client request. This, combined with the fact that the web server can compress the web content on-the-fly, has greatly reduced the waste of bandwidth and system resources.

How it works

Fast-Static-Feed performs the following actions:

• Every time a post is published or an already published post is edited, the plugin dumps the entries feed (that is the feed of the blog posts) to a file. This way, the static XML file is always contains the most fresh content of your blog.
• Every time a feed is requested, instead of re-generating the XML content over and over, this plugin delivers the static XML file. This is completely transparent to the client as there are no HTTP redirects involved. Your content is just being delivered faster!
• If the plugin is enabled, but the static files have not been created yet, the plugin will try to generate them automatically. Upon failure to do so, a 404 Not Found HTTP error code will be returned to the client.
• It also checks if the client’s request includes the If-Modified-Since HTTP header and, in such a case, it checks the static file’s modification time. If the client’s cache is current, it just returns a 304 Not Modified status to further reduce bandwidth usage.

The plugin caches all four types of feeds WordPress supports -RSS 2.0, Atom 1.0, RDF, RSS 0.92-.

Only the feeds that contain your blog posts are cached. The comments feed, each individual post’s comments feed, feeds for categories, tags, authors etc are still generated dynamically every time they are requested.

This plugin does not interefere in any way with the generation of rewrite rules and the generation of your site’s feed links.

Configuration

Generally, the plugin does not require any configuration in order to work.

One mandatory prerequisite is that the wp-content/ directory is writable by the web server. If it is not, the plugin will not be able to create the static files and, consequently, the clients who request a feed will receive a 404 Not Found HTTP code.

Furthermore, there are two options within the source code fast-static-feed.php that can be set.

// By default, the WordPress feeds contain elements of the 'wfw' namespace
// (CommentAPI), so a feed reader can fetch each feed entry's comments.
// By setting the following to 1, these elements will be stripped
// from the static feed.
// It is recommended to set this to 1 in order to save bandwidth.
// More info: http://wellformedweb.org/news/wfw_namespace_elements/
$FSF_STRIP_COMMENTS = 0;
// Set the following to 1 and various messages will be recorded in the logfile,
// which is located in the cache dir (wp-content/cache-xml/)
$FSF_DEBUG = 0;

It has already been mentioned, but it is important to note it again: The only mandatory prerequisite is that wp-content/ is writable by the webserver.

Installation

Make any changes to the configuration options within fast-static-feed.php and upload the file to wp-content/plugins/ directory. Then, activate the plugin through the WordPress administration panel.

License

Fast-Static-Feed is an open-source project, released as Free Software under the terms of the Apache License version 2.

Downloads, Issue Tracking, Support

For the latest releases of Fast-Static-Feed please visit the downloads section of the Fast-Static-Feed Development Portal.

The development website also hosts an issue tracking facility, where you can submit your feature requests or report bugs, and discussion boards, where you can get first class support from the community of users.

Donate

This plugin is released as free software. Nevertheless, its development requires time and effort. A small donation, as a sign of appreciation of the effort, is welcome. Please, use the following button to visit the Donations page. Thanks in advance for your support!

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