Linux How to use, Tutorials and scripts; Guides

Download and Extract SSL certificates After getting an SSL certificate in a zip file via your email, download and extract certificate files (primary and intermediate certificate) to a local directory. Replace old minserv.pem file: Locate miniserv.Pem file (usually in /etc/webmin/). Now it is time to replace mineserv.Pem file with a combination of a private key and primary certificate. Basically, you can create a new miniserv.Pem file in two ways. Run the command : cat private.key yourcommonname.crt > new_miniserv.pem Note: the private.key used in the above command is the file of your private key and

CentOS 6 Click [View Console] to access the console and click the send CTRL+ALT+DEL button on the top right. Alternatively, you can also click [RESTART] to restart the server. You will see a GRUB boot prompt telling you to press any key - you have only a few seconds to press a key to stop the automated booting process. (If you miss this prompt you will need to restart the VM again) At the GRUB prompt, type "a" to append to the boot command. Add the text "single" and press enter. System will boot and you will see the root prompt. Type "passwd" to change the root-password and then reboot again. CentOS 7 Click [View Console] to access the console and click the send CTRL+ALT+DEL button on the top right. Alternatively, you can also click [RESTART] to restart the server. As soon as the boot process starts, press ESC to bring up the GRUB boot prompt. You may need to turn the system off from the control panel and then back on to reach the GRUB bo...

1. Install AIDE package on CentOS/RHEL: # yum install -y aide 2. Check and adjust aide configuration file to fulfill your needs: # vim /etc/aide.conf 3. Initialize AIDE database - it will scan all the files in folders that were included in the config file and save their hash as well as attributes info 4. You may consider keeping golden copy of AIDE database (default is set to /var/lib/aide/aide.db.gz) is secure and read-only location. It will allow you to compare current system integrity to the golden copy. To check what changed run: # aide -C If you get "Couldn't open file /var/lib/aide/aide.db.gz for reading" error it means you need to move database generated in step 3 to this location: #  mv /var/lib/aide/aide.db.new.gz /var/lib/aide/aide.db.gz

Error:  fatal: parameter inet_interfaces: no local interface found for ::1 [root@Centos7 postfix]# systemctl restart postfix Job for postfix.service failed because the control process exited with error code. See "systemctl status postfix.service" and "journalctl -xe" for details. [root@Centos7 postfix]# systemctl status postfix.service ● postfix.service - Postfix Mail Transport Agent    Loaded: loaded (/usr/lib/systemd/system/postfix.service; enabled; vendor preset: disabled)    Active: failed (Result: exit-code) since Tue 2018-01-02 16:50:43 IST; 4s ago   Process: 12908 ExecStart=/usr/sbin/postfix start (code=exited, status=1/FAILURE)   Process: 12905 ExecStartPre=/usr/libexec/postfix/chroot-update (code=exited, status=0/SUCCESS)   Process: 12901 ExecStartPre=/usr/libexec/postfix/aliasesdb (code=exited, status=75) Jan 02 16:50:41 Centos7.windows.local systemd[1]: Starting Postfix Mail Transport Agent... Jan 02 16:50:41 Centos7.windo...

1. Create separte partation for tmp , if you don't have the space to create a fresh /tmp partition on existing drives, you can use the loopback capabilities of the Linux kernel by creating a loopback filesystem that will be mounted as /tmp and can use the same restrictive mount options. To create a 1GB loopback filesystem, execute the following commands. [root@Centos7 ~]# dd if=/dev/zero of=/dev/tmpDIR bs=1024 count=1000000 1000000+0 records in 1000000+0 records out 1024000000 bytes (1.0 GB) copied, 5.32903 seconds, 192 MB/s 2. Backup Current /tmp Directory: Now backup the current /tmp directory using the syntax below which will keep the same permissions for the files currently in /tmp. [root@Centos7 ~]# cp -Rpf /tmp /tmpbak 3.Modify fstab: You should add a line to the end of the /etc/fstab file so the tmp partation so tmp is mounted when the server reboots. /dev/mapper/centos-tmp  /tmp                    xfs  ...

1. NTP package is provided by default from Centos  repositories, and can be installed by the following command: [root@Centos7 ~]# yum -y install ntp 2. Configure these lines. [root@Centos7 ~]# vi /etc/ntp.conf # line 18: add the network range you allow to receive requests restrict 172.160.0.0 mask 255.255.0.0 nomodify notrap # change servers for synchronization #server 0.centos.pool.ntp.org iburst #server 1.centos.pool.ntp.org iburst #server 2.centos.pool.ntp.org iburst #server 3.centos.pool.ntp.org iburst server ntp1.example.local iburst server ntp2.example.local iburst 3. Once the installation completes, start the service and configure it so it starts automatically each time the server boots: [root@Centos7 ~]# systemctl start ntpd [root@Centos7 ~]# systemctl enable ntpd 4. Add the NTP service in firewall [root@Centos7 ~]# firewall-cmd --add-service=ntp --permanent success [root@Centos7 ~]# firewall-cmd --reload success 5. To get a basic report you c...

MySql - Convert InnoDB to MyISAM Storage Engine of Database To convert Database InnoDB Tables to MyISAM steps follow these steps 1. Take the backup of Mysql database [root@Centos7 ]# mysqldump -f --opt mysqldb > /usr/mysqldb.sql 2. Convert the ENGINE from InnoDB to MYISAM  by using below commans. [root@Centos7 ]#mysql -u username -p -e "SELECT concat('ALTER TABLE ', TABLE_NAME,' ENGINE=MYISAM;') FROM Information_schema.TABLES WHERE TABLE_SCHEMA = 'db_name' AND ENGINE = 'InnoDB' AND TABLE_TYPE = 'BASE TABLE'" | tail -n+2 >> /root/MYISAM.sql Note : Update  username and db_name values with your own values. 3. mport that MYISAM.sql file into INNODB database [root@Centos7 ]# mysql -u username -p mysqldb < /root/MYISAM.sql 4. Make it permanent, add to my.cnf default-storage-engine= MyISAM