web development and system administration of Linux
If you getting error: 1042: Can’t get hostname for your address when trying to connect when trying to dump remote database using mysqldump it can be fixed by adding configuration directive:
skip-name-resolve
into section [mysqld]
Also, MySQL service should be restarted using command:
# /etc/init.d/mysqld restart
Stopping mysqld: [ OK ]
Starting mysqld: [ OK ]
To install rkhunter on Linux servers I am usually using the following procedure:
# mkdir -pv /root/install # cd /root/install/ # wget -O rkhunter-1.tar.gz http://sourceforge.net/projects/rkhunter/files/latest/download?source=files # tar xzf rkhunter*.tar.gz # cd rkhunter* # sh installer.sh --layout default --install
To find out where it is installed I am use command:
# whereis rkhunter
rkhunter: /usr/bin/rkhunter /etc/rkhunter.conf /usr/share/man/man8/rkhunter.8
To update rkhunter databases run:
# /usr/bin/rkhunter --update
[ Rootkit Hunter version 1.4.0 ]
Checking rkhunter data files…
Checking file mirrors.dat [ No update ]
Checking file programs_bad.dat [ No update ]
Checking file backdoorports.dat [ No update ]
Checking file suspscan.dat [ No update ]
Checking file i18n/cn [ No update ]
Checking file i18n/de [ No update ]
Checking file i18n/en [ No update ]
Checking file i18n/zh [ No update ]
Checking file i18n/zh.utf8 [ No update ]
#
Also, I have created bash script:
# more /root/bin/update_and_check_rkhunter.sh
#!/bin/bash date /usr/bin/rkhunter --configfile /etc/rkhunter.conf --versioncheck /usr/bin/rkhunter --configfile /etc/rkhunter.conf --update /usr/bin/rkhunter -c --configfile /etc/rkhunter.conf --cronjob --propupd --createlogfile date
#
… to check rkhunter version, update databases and run system check and added it to cron:
# crontab -l
1 2 * * 1 /root/bin/update_and_check_rkhunter.sh >/root/reports/update_and_check_rkhunter.log 2>&1
To fix problem with cPanel / WHM upgrade if:
error: Failed dependencies:
MySQL conflicts with mysql-5.0.x
Read: http://docs.cpanel.net/bin/view/AllDocumentation/InstallationGuide/RPMTroubleshoot and forum posts http://forums.cpanel.net/f5/case-64049-overnight-update-failed-mysql-conflicts-mysql-5-0-77-4-el5_4-2-i386-320381.html
Made all MySQL databases backup and run command as root user:
# rpm -e –nodeps –allmatches –justdb mysql-5.0.x
It will resolve Conflict With Rogue mysql RPM.
Run cPanel / WHM update once again.
Sometimes I need .htaccess mod_rewrite rule to redirect old URL to new one.
I am using the following rules:
# Add followsymlinks to server options
Options +FollowSymLinks
# It will work only if web server Apache mod_rewrite is enabled
<IfModule mod_rewrite.c>
# Turn on mod_rewrite engine
RewriteEngine On
# Should be added if virtual document root directive is used
RewriteBase /
# Redirect from /old-url
# to –> /new-url
RewriteCond %{REQUEST_URI} ^/old-url
RewriteRule ^old-url(.*)$ http://%{HTTP_HOST}/new-url$1 [NC,R=301,L]
</IfModule>
Notes:
%{REQUEST_URI} – web server Apache requested URL
%{HTTP_HOST} – your domain name: e.g. www.shkodenko.com or shkodenko.com
$1 – can be additional URL part including get parameters substituted from (.*)
To set up full text search parameter minimum word length edit your main MySQL configuration file /etc/my.cnf.
In section
[mysqld]
# set minimum word length for full text search
ft_min_word_len=3
Restart MySQL using command:
# /etc/init.d/mysqld restart
Documentation: http://dev.mysql.com/doc/refman/5.0/en/fulltext-search.html
1. IPTables configuration.
If you have IPTables firewall enabled add rule
-A INPUT -m state –state NEW -m tcp -p tcp –dport 63000:65535 -j ACCEPT
to IPTables configuration file /etc/sysconfig/iptables
and restart IPTables service:
# /sbin/service iptables restart
iptables: Flushing firewall rules: [ OK ]
iptables: Setting chains to policy ACCEPT: filter [ OK ]
iptables: Unloading modules: [ OK ]
iptables: Applying firewall rules: [ OK ]
#
To check if your new rule active run command:
# /sbin/iptables -vnL –line-numbers |more
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
num pkts bytes target prot opt in out source destination
…
11 62 3720 ACCEPT tcp — * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpts:63000:65535
2. ProFTPD server configuration.
First step before making any changes to configuration files is to create backup:
# cp -fvp /etc/proftpd.conf /etc/proftpd.conf.bak
Second step is to check service configuration to make sure it is correct.
# proftpd -td10
Checking syntax of configuration file
…
Syntax check complete.
Add configuration lines to config file /etc/proftpd.conf:
MasqueradeAddress shkodenko.com
PassivePorts 63000 65535
under
ServerName “ProFTPD”
directive
Check service configuration to make sure it is correct after applying our changes.
# proftpd -td10
Checking syntax of configuration file
…
Syntax check complete.
Restart service.
If your ProFTPD server installed as part of xinetd:
# /sbin/service xinetd restart
Stopping xinetd: [ OK ]
Starting xinetd: [ OK ]
If your ProFTPD server installed as standard Linux service:
# /sbin/service proftpd restart
or
# /etc/init.d proftpd restart
I would like to share with you nice process monitoring program htop.
I am using this program on my Fedora Linux desktop, CentOs and RHEL (Red Hat Enterprise) Linux servers.
To install it several dependent system packages should be installed as root administrator user:
# yum install ncurses ncurses-devel ncurses-libs
Change directory to your installation directory location. Mine is /root/install
# cd /root/install
Download htop using wget:
# wget --output-document=htop-1.0.2.tar.gz http://sourceforge.net/projects/htop/files/htop/1.0.2/htop-1.0.2.tar.gz/download
Unpack it:
# tar xzvf htop-1.0.2.tar.gz
Change to directory unpacked program folder:
# cd htop-1.0.2
Configure it:
# ./configure
By default htop binary is installed to /usr/local/bin directory. You can change it by passing –prefix parameter to ./configure script
Also, you can create symbolic link using command ln -s /usr/local/bin /root/bin
Make:
# make
Install
# make install
When you need to print CRC checksum and byte count for file in Linux use cksum command.
Sample usage:
$ cksum /home/taras/file.txt
1913889276 220 /home/taras/file.txt
Where:
– 1913889276 – CRC checksum;
– 220 – size in bytes;
– /home/taras/file.txt – file name.
To mount Windows samba share on Linux:
1. Log in as root administrator user.
2. Create mount point:
# mkdir -pv /mnt/share_name
3. Mount share to it using command:
# mount -t cifs -o username=User,password=Password //192.168.0.123/share_name /mnt/share_name
4. Use files from Windows share located in /mnt/share_name
Note, User should have access to Windows share //192.168.0.123/share_name
To disable Dr Web update cron notifications via e-mail in Plesk for Linux:
1. Edit file Dr Web configuration file /etc/drweb/drweb32.ini using your favorite editor. Mine is vim:
# vim /etc/drweb/drweb32.ini
# CronSummary = yes
# —>
CronSummary = no
2. Edit file /etc/cron.d/drweb-update and add to the end of string >/dev/null 2>&1
# more /etc/cron.d/drweb-update
*/30 * * * * drweb /opt/drweb/update.pl >/dev/null 2>&1
#
3. If user drweb has cron jobs
# crontab -u drweb -l
55 2,7,12,17,20 * * * /opt/drweb/update.pl
change it to:
55 2,7,12,17,20 * * * /opt/drweb/update.pl >/dev/null 2>&1
4. If file /usr/local/psa/etc/drweb-update exists
# vim /usr/local/psa/etc/drweb-update
Change its content from:
#!/bin/sh exec /opt/drweb/update.pl
to:
#!/bin/sh
exec /opt/drweb/update.pl >/dev/null 2>&1
