HTML Help files are made with help authoring tools. Microsoft ships the HTML Help Workshop with supported versions of Microsoft Windows and makes the tool available for free download. There are also a lot of third-party help authoring tools available.

CHM files, known as Microsoft Compressed HTML Help files, are a common format for eBooks and online documentation. They are basically a collection of HTML files stored in a compressed archive with the added benefit of an index.

Under Linux, you can view a CHM file with the xchm viewer. But sometimes that’s not enough. Suppose you want to edit, republish, or convert the CHM file into another format such as the Plucker eBook format for viewing on your Palm. To do so, you first need to extract the original HTML files from the CHM archive.

This can be done with the CHMLIB (CHM library) and its included helper application extract_chmLib.

Install Chmlib in Ubuntu

sudo apt-get install libchm-bin

Convert .chm files in to HTML files

If you want to convert .chm files in to HTML files use the following command

extract_chmLib book.chm outdir

where book.chm is the path to your CHM file and outdir is a new directory that will be created to contain the HTML extracted from the CHM file.

Convert .chm files in to PDF files

First you need to install htmldoc. HTML processor that generates indexed HTML, PS, and PDF.HTMLDOC is a program for writing documentation in HTML and producing indexed HTML, PostScript, or PDF output (with tables of contents). It supports most HTML 3.2 and some HTML 4.0 syntax, as well as GIF, JPEG, and PNG images.

sudo apt-get install htmldoc

If you want to use htmldoc type the following command in terminal

htmldoc

Once it opens you should see similar to the following screen here you can choose the html file and convert them to pdf,ps

You need to install xchm, which will read chm files. (chm files are Microsoft help files.) To install xchm, open a terminal and type:

How it is used

• test if a string or its substring matches with some pattern.

For example, if the user input in a form contains all digits, legal phone number patterns, credit card number patterns, or date patterns.
• replace or substitute some string pattern in a text string.

For example, remove all tags in a web page and only leave text content.
• extract substring from a string based on certain text pattern.

For example, given a URL, extract the protocol, domain name, port no., and uri fields for further processing such as web crawling, web indexing/searching, or copying web pages for offline reading.

Web Pag for Testing Your Regulart Expression with provided data

http://cs.uccs.edu/~cs301/testreg.html

Reference:

• Mastering Regular Expressions by Jeff Friedl, Oreily.
• Perlre man page ("man perlre")

Perl Metacharacter Summary

Items to match a single characters

Example 1: character class
if ($string =~ /[01][0-9]/) {
print "$string contains digits 00 to 19\n";
} else {
print "$string contains digits 00 to 19\n";
}

Example 2: negated character class
if ($string =~ /[^A-z]/) { print "$string contains nonletter characters\n"}
else { print "$string does not contains non-letter characters.\n"}

Class Shorthand: Items that match a single character in a predefined character class

Quantifiers: Items appended to provide "Counting"

Items That Match Positions

Grouping and Alternation

Modes, append at the end of regular expression

Need for a tabbed version of famous PuTTY? That's exactly what PuTTY Connection Manager does.
PuTTY Connection Manager is a free PuTTY Client Add-on for Windows platforms which goal is to provide a solution for managing multiple PuTTY instances.

Below is a cut from features:

• Tabs and dockable windows for PuTTY instances
• Fully compatible with PuTTY configuration (using registry)
• Easily customizable to optimize workspace (fullscreen, minimze to tray, add/remove toolbar, etc…)
• Automatic login feature regardless to protocol restrictions (user keyboard simulation)
• Post-login commands (execute any shell command when logged)
• Connection Manager: Manage a large number of connections with specific configuration (auto-login, specific PuTTY Session, post-command, etc.)
• Quick connect toolbar to quickly launch a PuTTY connection
• Import/Export whole connections informations to XML format (generate your configuration automatically from another tool and import it, or export your configuration for backup purpose)
• Encrypted configuration database option available to store connections informations safely (external library supporting AES algorithm used with key sizes of 128, 192 and 256 bits, please refer for the legal status of encryption software in your country)
• Standalone executable, no setup required
• Localizable: English (default) and French available (only when using setup version, standalone is english only)
• Completely free for commercial and personal use: PuTTY Connection Manager is freeware

Search

Preparation

1. Back up the following files:

   /etc/mail/sendmail.cf /etc/sendmail.cf /etc/mail/submit.cf /usr/sbin/sendmail

2. Create a user and group called `smmsp':

   useradd smmsp groupadd smmsp

   This step is essential, as sendmail will not start up unless it has its own userid.
   The entries in /etc/passwd and /etc/group should look something like this:
   

   cat /etc/passwd | grep smmsp smmsp:x:25:25:Sendmail:/home/smmsp:/bin/false cat /etc/group | grep ^smmsp smmsp:x:25:smmsp

Install libdb

cd db-4.2.52/build_unix
../dist/configure
make
su
make install

1. First, copy db.h to /usr/include. This is essential, as the db.h must match the library. If it doesn't, sendmail won't compile.

   cd db-4.2.52 cp build_unix/db.h /usr/include/

   
   
2. Second, get rid of the old libdb libraries.

   cd /usr/lib mkdir libdb-old mv libdb* libdb-old

   
   
3. Third, add the new libdb path (/usr/local/BerkeleyDB.4.2/lib) to /etc/ld.so.conf and reconfigure the run-time linker.

   vi /etc/ld.so.conf ldconfig

Compile and install sendmail

touch /usr/include/linux/version.h
tar -xzvf sendmail.8.11.6.tar.gz
cd send*

1. First, edit the config files if you plan to use procmail.

   cd cf/cf cp generic-linux.mc sendmail.mc

   Edit sendmail.mc and add

   MAILER(procmail)dnl

   at the end. Add any other commands as needed.
2. Create and install new config files using the following command:

   sh Build sendmail.cf sh Build submit.cf su make install-cf

   In earlier versions, the submit.cf file was not copied automatically if an old version of the file already existed. If you try to use an old version of submit.cf, when you start sendmail it will say:

   NOQUEUE: SYSERR(root): can not chdir(/var/spool/clientmqueue/): Permission denied

   This error can also occur if sendmail is running as the wrong user or group.
   
   Alternatively, install the config files manually.

   cd cf/cf cp config.cf /etc/mail/sendmail.cf cp submit.cf /etc/mail/

3. Create a devtools/Site/site.config.m4 file containing the paths for libdb. Change the paths to indicate wherever the libdb libraries and include files are located.

   APPENDDEF(`confMAPDEF', `-DNEWDB')dnl APPENDDEF(`confINCDIRS', `-I/usr/include/db2') APPENDDEF(`confLIBDIRS', `-L/usr/lib') APPENDDEF(`confLIBS', `-ldb')

   The exact syntax will vary depending on your system. On one of our computers, where we installed a new libdb, the file contained the following four lines:

   APPENDDEF(`confLIBS', `-lssl -lcrypto -ldb') APPENDDEF(`confLIBDIRS', `-L/usr/local/ssl/lib -L/usr/local/ssl/lib -L/usr/local/BerkeleyDB.4.2/lib -L/usr/lib') APPENDDEF(`confINCDIRS', `-I/usr/local/ssl/include -I/usr/include') APPENDDEF(`confMAPDEF', `-DNEWDB')dnl

   Sometimes compilation fails with undefined references to `pthread_mutex_trylock' and other pthread functions. If this happens, change the confLIBS line to

   APPENDDEF(`confLIBS', `-ldb -lpthread')

   
   NOTE: If you use the site.config.m4.example file that is included with sendmail, be sure to comment out items you don't want, or sendmail will probably not compile.
   
   
4. Compile sendmail

   sh Build

   If you change any configuration files and need to compile a second time, use the -c option.

   sh Build -c

   The -c option rebuilds all the files to include your changes. It should automatically add the correct options to the commands, for example:

   cc -O2 -I. -I../../sendmail -I../../include \ -I/usr/include/db2 -DNEWDB -DNEWDB -DNOT_SENDMAIL \ -c -o vacation.o vacation.c

   
   IMPORTANT: It's necessary to watch the screen continuously while sendmail is building, because the build script does not stop if there's an error.
   
   If your linux system is really old, you will get error messages like

   map.c:2084: `DB_FCNTL_LOCKING' undeclared (first use in this function)

   This means you need to install a newer copy of the Berkeley DB libraries from www.sleepycat.com.
5. Check to make sure it created an executable sendmail in the directory obj.Linux.#.#.##.i686/sendmail. If it bombs out, edit the file include/libsmdb/smdb.h, removing the lines

   # ifndef NDBM # ifndef NEWDB ERROR NDBM or NEWDB must be defined. # endif /* ! NEWDB */ # endif /* ! NDBM */

   and type sh Build -c again.
6. Install the new sendmail

   sh Build install

   Scroll back through the output and make sure there were no errors. If it says:

   install: invalid group `smmsp' make[1]: *** [install-sendmail] Error 1

   you must fix the groups and repeat.
7. Set the correct permissions and ownerships:

   mkdir /var/spool/clientmqueue chown smmsp:smmsp /var/spool/clientmqueue chmod 770 /var/spool/clientmqueue chmod 700 /var/spool/mqueue chown root.root /var/spool/mqueue chmod 777 /var/spool/mail chown root.root /var/spool/mail chmod 4555 /usr/sbin/sendmail chown root.smmsp /usr/sbin/sendmail

   NOTE: /var/spool/mail must be world read/write, otherwise clients can't open their inbox. The permissions for individual mailboxes for each user should be 600:

   -rw------- 1 daboss users 20219537754 2006-03-31 10:15 daboss

   
   Check to make sure of the following:

   -r-sr-xr-x root smmsp /usr/sbin/sendmail drwxrwx--- smmsp smmsp /var/spool/clientmqueue drwx------ root root /var/spool/mqueue -r--r--r-- root bin /etc/mail/sendmail.cf -r--r--r-- root bin /etc/mail/submit.cf

   
   
8. Add a local-host-names file.

   cp /etc/sendmail.cw /etc/mail/local-host-names

   If local-host-names doesn't exist, create one. It should contain a single line:

   myhost.mydomain.org

   If the server has more than one name, add them to this file, one per line.

Testing sendmail

1. First, as root, test it to make sure the 'newaliases' command works. If it says

   Cannot rebuild aliases: no database format defined Cannot create database for alias file /etc/mail/aliases

   It means sendmail couldn't find the libdb files. Check that db.h is in /usr/include, that the new libraries are in their correct location, the old ones have been removed, and that /etc/ld.so.conf has a line indicating the path to the new libraries.
2. Restart inetd to make sure imap and pop3 aren't crashing.
3. Make sure sendmail is running. Unlike earlier versions, it sometimes now has two or more entries:

   ps -aux | grep mail root Mar30 0:01 sendmail: accepting connections smmsp Mar30 0:00 sendmail: Queue control smmsp Mar30 0:01 sendmail: running queue: /var/spool/clientmqueue

4. Test to make sure users can send and receive mail in all of the following:
   1. smtp client (e.g. pine)
   2. http (e.g. squirrelmail via browser)
   3. pop3 client (e.g. windows)
   4. imap4 client (e.g. windows)
   Also, check the system logs to make sure there are no weird error messages.
5. If you like pain and you want to change sendmail.cf, the easiest way is to edit sendmail.mc and then create it using

   m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

6. You may wish to test to ensure that your sendmail installation is not acting as an open mail relay by typing the command: telnet relay-test.mail-abuse.org There is also a web service at www.abuse.net/relay.html. You can download software to test it yourself from http://www.monkeys.com/mrt/. To be valid, the testing must be done using an account on a machine in some other domain (such as a temporary email account on abuse.net).
   
   However, testing this way is risky. If the testing software discovers that you're an open relay, your hostname or even your entire domain may end up in their public blacklist, thereby blocking valid email sent by your users. Last time I checked, the testing site www.ordb.org does this. We have found these blacklists are so inaccurate that we had to disable the blacklist check in spamassassin to avoid losing incoming mail. Thus, remote testing may do more harm than good.

Error messages

/usr/local/BerkeleyDB.4.2/lib/libdb.so: undefined reference to `pthread_condattr_setpshared'
/usr/local/BerkeleyDB.4.2/lib/libdb.so: undefined reference to `pthread_mutexattr_destroy'
/usr/local/BerkeleyDB.4.2/lib/libdb.so: undefined reference to `pthread_mutexattr_setpshared'
/usr/local/BerkeleyDB.4.2/lib/libdb.so: undefined reference to `pthread_mutexattr_init'
/usr/local/BerkeleyDB.4.2/lib/libdb.so: undefined reference to `pthread_mutex_trylock'

APPENDDEF(`confLIBS', `-ldb -lpthread')

Initializing SMTP port (sendmail)/etc/mail/submit.cf: 
    line 430: readcf: option RunAsUser: unknown user smmsp: 
    No such file or directory 

su
Cannot rebuild aliases: no database format defined
Cannot create datase for alias file /etc/mail/aliases  

SMTPD_LISTEN_REMOTE="yes"

Tweaking sendmail configuration

1. Changing hostname: Some computers are on two different domains. To get sendmail to use the second domain in its headers instead of your FQDN, add the following to submit.mc and sendmail.mc:

   FEATURE(always_add_domain)dnl MASQUERADE_AS(got-syphilis.seconddomain.org)dnl FEATURE(masquerade_envelope)dnl

   It may also be necessary to change the settings in your email client. For example, in pine, if you have the line:

   customized-hdrs = Reply-To: nbonaparte@grand-armee.fr

   change it to

   Reply-To: nbonaparte@got-syphilis.seconddomain.org

2. Slowing down dictionary attacks and distributed denial of service (DDoS) attacks: (this information is from http://www.technoids.org/dossed.html).
   Add the following to sendmail.mc:

   # block dos attacks # no of seconds connection rate FEATURE(`access_db')dnl FEATURE(`ratecontrol', ,`terminate')dnl define(`confCONNECTION_RATE_WINDOW_SIZE',`10')dnl # no of connections simultaneously define(`confCONNECTION_RATE_THROTTLE', `8')dnl FEATURE(`conncontrol', ,`terminate')dnl define(`confBAD_RCPT_THROTTLE',`10')dnl FEATURE(`greet_pause', `5000')dnl # stop dictionary attacks define(`confMAX_RCPTS_PER_MESSAGE', `10')dnl

3. Stopping server from sending receipts: Some people try to check up on you by requesting a receipt when the email is delivered. Spammers may also use this to validate your users' email addresses.

   # no receipts on delivery define(`confPRIVACY_FLAGS', `noreceipts')dnl

   Check your email client; some clients send receipts as well.

Dump a single table to a SQL file:

<code>mysqldump -uuser -ppassword dbName tableName > backup.sql</code>

If you want to get or restore a single table from a large MySQL dump file you can use the following methods:
Using AWK
Using Ruby
Using Perl:

<code>#!/usr/bin/perl -wn<br />BEGIN {<br />  $table = shift @ARGV;<br />  $printing = 0;<br />}<br />$printing = 1 if /^create table $table\b/io;<br />exit if $printing && /^create table (?!$table)\b/io;<br />print if $printing;</code>

Invocation:

<code>perl gettablefromdump.pl tablename dumpfile.sql<br /><br />Reference: <a href="http://www.sysadmin.md/backup-and-restore-a-single-mysql-table.html">http://www.sysadmin.md/backup-and-restore-a-single-mysql-table.html</a><br /></code>

ProFTPd is a high-performant, extremely configurable and most of all secure FTP server written for use on Unix and Unix-like operating systems. The FTP daemon has Apache-like configuration syntax and supports virtual servers – a parallel FTP environments that are physically located on the same system but that answer to different IP addresses or ports.

ProFTPD generally uses a single configuration file, found at /etc/proftpd.conf or at /etc/proftpd/proftpd.conf. This small cheatsheet describes directives in config file that helps to harden currently running ProFTPd instance.

To quickly secure ProFTPd server – open config file and make the following changes:

<code>ServerType standalone
ServerName "SysAdmin.MD secured FTP server"
ServerIdent on "FTP server"
DeferWelcome on

UseIPv6 off
IdentLookups off

MaxInstances 30
MaxClients 10
MaxLoginAttempts 10 "Maximum number of allowed users are already connected (%m)"

DefaultRoot ~
AllowFilter "^[a-zA-Z0-9 ,]*$"
</code>

Below is a short explanation for each directive:

ServerType
Set the mode ProFTPd runs in. In standalone mode, a new connections to the server results in spawned child process for each new-connected client.

ServerIdent
Sets the default message displayed when a new client connects. You can check this message by connecting with telnet to ftp port. Example:

<code>srv:~# telnet 127.0.0.1 21<br />Trying 127.0.0.1...<br />Connected to 127.0.0.1.<br />Escape character is '^]'.<br />220 <strong>FTP server</strong></code>

DeferWelcome
Enabling this directive makes initial welcome message to be exceedingly generic and do not give any type of information about the host.

UseIPv6
Set to off to disable IPv6 protocol support which is annoying on IPv4 only boxes.

IdentLookups
Tells ProFTPd to disable attempts to identify the remote username when a client initially connects to the server.

MaxInstances
The directive configures the maximum number of child processes that may be spawned by a parent proftpd process in standalone mode. This directive is used to prevent undesirable denial-of-service attacks.

MaxClients
Configures the maximum number of authenticated clients which may be logged into a server. Once this limit is reached, additional clients attempting to authenticate will be disconnected with message:
Maximum number of allowed users are already connected.

DefaultRoot
The DefaultRoot directive controls the default root directory assigned to a user upon login.
Symbol ~ means that the client is chroot-jailed into their home directory

AllowFilter
AllowFilter controls what characters may be sent in a command to ProFTPD to prevent some possible types of attacks against FTP daemon.
Symbols "^[a-zA-Z0-9 ,]*$" tells to daemon to only accept commands containing alphanumeric characters and white-space.

Reference: http://www.sysadmin.md/secure-existing-proftpd-server-installation.html

Protocol 2

PermitRootLogin without-password
StrictModes yes
Banner /etc/sshd_banner

LoginGraceTime 60
MaxAuthTries 3
MaxStartups 10

PermitEmptyPasswords no
PrintLastLog yes
AllowTcpForwarding no

IgnoreRhosts yes
IgnoreUserKnownHosts yes
HostbasedAuthentication no</code>

This is secured SSH service. Your activities are logged and monitored.

Warning: Unauthorized access to this system is strictly prohibited.

Keeping good database backups is crucial because unpredictable disastrous events always occurs. In web-based business – backup is a critical component.

Exists different open-source scripts, that could help to organize the database backup process in a customized and easy way, avoiding use of mysqldump (default MySQL backup tool).

This post describes various open-source scripts that can help a newbie sysadmin to organize MySQL backup process.

AutoMySQLBackup

Homepage | Downloads

A shell script to take daily, weekly and monthly backups of MySQL databases using mysqldump. It's features includes: backing up mutiple databases, create a backup into a single backup file or to a separate file for each DB, backup files compression, backup to remote server, e-mail user when backup is completed and others.

Backup2Mail

Homepage | Download

Backup2Mail is a PHP script that creates regular backups of MySQL databases and sends them to configurable e-mail address. The whole process can be scheduled with a help of Cron (for Unix/Linux) or with Task Scheduler (for Windows).

mylvmbackup

Homepage | Download

mylvmbackup is utility for creating MySQL backups via LVM snapshots. To perform this, mylvmbackup obtains a read lock on all tables, flushes all server caches to disk, creates a snapshot of the volume containing the MySQL data directory and unlocks the tables again. The LVM snapshot is mounted to a temporary directory and all data is backed up using the tar or rsync program. Script requires Perl5 and LVM utilities.

MyPHPdumpTool (mpdt)

Homepage | Downloads

MyPHPdumpTool is a PHP (CLI) based MySQL backup tool that can be configured to automatically archive and upload any database-dump file to any FTP server. The backup process can be scheduled with a help of Cron (for Unix/Linux) or with Task Scheduler (for Windows).

mysqlblasy (MySQL backup for lazy sysadmins)

Homepage | Download

mysqlblasy is a Perl script for automating MySQL database backups. The main feature of this script is automatic backups rotation to avoid that the backup disk gets full when the administrator is on vacation (or is lazy). Each database gets dumped into a separate file, after which all the dumps get tarred/compressed and placed into the specified backup directory. Old files in the backup directory get deleted, and the number of newest files that is specified in configuration file is kept.

mysqldumper

Homepage | Download Page

MySQLDumper is a script for backing up MySQL databases written in PHP and Perl. It uses a proprietary technique to avoid execution interruption by reading and saving a certain amount of commands, then calling itself via JavaScript to memorize how far in the process it was. Finally, the script resumes its action from last standby.

phpMyBackupPro

Homepage | Download Page

phpMyBackup Pro is a very easy to use, free, web-based MySQL backup script, licensed under the GNU GPL. Script allows a lot of operations such: backup of one or several databases with or without data, table structure; backup directly onto FTP server and sending of backups by email; manage, restore and schedule backups and others. phpMyBackup Pro is platform independent: it requires only a web-server and PHP.

Sypex Dumper Lite

Homepage | Download Page

Sypex Dumper Lite is developed by specialists of Ukrainian company and it is a PHP script for quick and easy MySQL database backup. The script is very fast with all types of databases (small or large), because it uses special technique for dumping: the backup file is not stored entirely in memory.

Zmanda Recovery Manager for MySQL (Community Edition)

Homepage | Download Page

Zmanda Recovery Manager (ZRM) for MySQL simplifies the life of a Database Administrator who needs an easy-to-use yet flexible and robust backup and recovery solution for MySQL server. The Community Edition is free and has a lot of features in a single utility: different types of backup (logical, incremental, lvm), backup rotation, schedule, remote server transfer, alerts. Also, it has additional features like: publish report to web site, RSS feed, point-in-time restore.

Reference: http://www.sysadmin.md/opensource-scripts-to-backup-mysql-databases.html