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    Creative Commons License
    This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
    PyBlosxom

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    Thu, 31 May 2012


    /Admin/iptables: How to Delete an iptables Rule

    For instance, suppose we are blacklisting this IP:

    DROP all -- 224.33.200.440 anywhere

    First get the iptables listing with line numbers:

    $ iptables -L --line-numbers
    
    Chain INPUT (policy DROP)
    num  target     prot opt source               destination
    1    DROP       all  --  203-173-249-170.dsl.dyn.ihug.co.nz  anywhere            
    2    DROP       all  --  224.33.200.440       anywhere
    3    DROP       all  --  60.247.102.150       anywhere
    4    DROP       all  --  60.213.51.50         anywhere
    etc....
    

    And then just drop (in this case) line #2:

    iptables -D INPUT 2

    posted at: 03:19 | path: /Admin/iptables | permanent link to this entry

    Mon, 28 May 2012


    /Security/privacy: Tip #1: Increase Privacy Through ISP Diversification

    Google recently became somewhat infamous when it became public knowledge that they are recording, storing, and analyzing every key stroke of their registered, logged-in users. Personally, I believe we can be fairly confident all (certainly all the big ones) online services are doing this to some extent. And the key words here are "registered" and "logged-in". If that is not your state then you have a chance to preserve some of your privacy.

    The behavior to be avoided is the use of one provider for everything, for instance: Google Search, Gmail, GTalk, Google+, etc. Then you are giving that one provider, in this case Google, EVERYTHING. And because you are using all Google's services, you can be fairly sure that you are always logged into Google in all your browsers, even if you use multiple browsers. Even with the best intentions you will often forget to log out and remain logged in for perhaps days without even knowing it.

    By "service provider diversification", I mean you should use different providers for different services. For instance, in my personal case, this is a simplified description of what I use daily:

    That way Google gets ONLY my social media activity and some chat. Microsoft gets ONLY my search activity (and at that, I am faceless to them because I do not need to login to use a search engine) and some of my chat. And gmx.com gets ONLY my private e-mail (actually, only some of it, because I also run my own e-mail server, which is even better -- all geeks should do this).

    posted at: 04:49 | path: /Security/privacy | permanent link to this entry

    Sat, 12 May 2012


    /Admin/Apache/PHP: How to Disable PHP Errors in a Specific Apache VirtualHost

    Add this line to the VirtualHost:

    php_value error_reporting 0

    [1] http://www.php.net/manual/en/function.error-reporting.php
    [2] http://www.php.net/manual/en/errorfunc.constants.php

    posted at: 06:23 | path: /Admin/Apache/PHP | permanent link to this entry

    Fri, 04 May 2012


    /Admin/databases/PostgreSQL: PostgreSQL Cheat Sheet

    /etc/postgresql/9.0/main/pg_hba.conf specifies the users that can access PostgreSQL. In Debian, the postgres user is the default. Therefore, to create a database[2]:

    sudo su
    su postgres
    createdb dbname

    Create a user and grant privileges on the new database:

    su postgres
    createuser uname
    psql dbname
    GRANT ALL PRIVILEGES ON DATABASE dbname TO uname;

    To create a database and user with SQL:

    su postgres
    psql
    CREATE DATABASE dbname;
    CREATE USER uname WITH PASSWORD 'pswd';
    GRANT ALL PRIVILEGES ON DATABASE dbname TO uname;

    To dump and then restore a database[1]:

    pg_dump dbname > outfile
    psql dbname < infile

    Simple SQL:

    psql
    --> Enter Postgres shell
    \?
    --> Postgres command help
    \l
    --> list all databases
    \c dbname
    --> connect to a database (similar to "use dbname;" in MySQL)
    \dt
    --> list all tables in database
    \d tname
    --> show table structure / columns of table tname
    SELECT * FROM tname;
    --> list contents of table tname
    SELECT * FROM tname WHERE colname='string';
    --> select on column contents exactly
    SELECT * FROM tname WHERE colname ~ 'string*';
    --> select using regular expression
    UPDATE tname SET colname='newstring' WHERE colname='oldstring';

    [1] http://www.postgresql.org/docs/9.0/interactive/backup-dump.html
    [2] http://www.yolinux.com/TUTORIALS/LinuxTutorialPostgreSQL.html

    posted at: 04:36 | path: /Admin/databases/PostgreSQL | permanent link to this entry