Configure DomainKeys- DKIM (OpenDKIM) with Postfix on CentOS 7 Rumi, March 31, 2021March 31, 2021 OpenDKIM is method to digitally sign & verify emails on the mail servers using public & private keys. In other words opendkim implements the DKIM (DomainKeys Identified Mail) standard for signing and verifying email messages on a per-domain basis. DomainKeys are implemented to reduce the chances of outgoing mails to… Continue Reading
Install LibreNMS Monitoring Tool with Nginx on Ubuntu 20.04 Rumi, March 30, 2021March 30, 2021 First, it is recommended to update your system packages to the latest version. You can do it with the following command: apt-get update -y After updating all packages, install all the dependencies required for LibreNMS with the following command: apt-get install rrdtool whois fping imagemagick graphviz mtr-tiny nmap python3-mysqldb snmp… Continue Reading
Setup mail server on centos 7 using postfix and dovecot Rumi, March 30, 2021 Installing packages Step 1 » Assign hostname for the server using the below command. [root@krizna ~]# hostnamectl set-hostname mail.krizna.com Step 2 » Make a host entry with your IP in /etc/hosts file. 172.27.0.51 mail.krizna.com Step 3 » Now start installing packages. [root@krizna ~]# yum -y install postfix dovecot After package… Continue Reading
Sectigo SSL certificate installation on Zimbra Rumi, March 30, 2021 1. Login to your Zimbra Admin Console using a browser. 2. In the left navigation pane under Home click Configure. Click Certificate. 3. On the right of the Zimbra Admin console click on the settings icon and select Install Certificate. 4. The Certificate Installation Wizard will pop up. 5. Under… Continue Reading
Install LAMP with PHP 7.4 on FastCGI/CGI configuration on CentOS 7 Rumi, March 24, 2021 Step 1 – Setup Yum Repository In the first step install all the required yum repositories in your system used in the remaining tutorial for various installations. You are adding REMI, EPEL, Webtatic & MySQL community server repositories in your system. CentOS / RHEL 7 yum install epel-release rpm -Uvh… Continue Reading
How to enable Proxy Settings for Yum Command on RHEL / CentOS Servers Rumi, March 24, 2021 This can be easily achieved with yum config file “/etc/yum.conf“. Under main section define the proxy settings like below: ……………… proxy=http://<Proxy-Server-IP-Address>:<Proxy_Port> proxy_username=<Proxy-User-Name> proxy_password=<Proxy-Password> ……………… Save and exit the file and start using the yum command. Sample yum Config file with proxy settings is shown below : Continue Reading
Ping behind proxy using httping Rumi, March 5, 2021 You can use utility httping for that. It sends a HEAD request (by default) to a web server and measures the time it took to get a response. The utility is available through a number of repositories for different OS’es and Linux distros: Ubuntu: sudo apt install httping Alpine: sudo… Continue Reading
enable SNMP on Xen (XCP-NG) hypervisors Rumi, March 5, 2021 There are six steps to correctly configuring SNMP on your Citrix Xen hypervisor. These steps don’t require a system restart and are non-service affecting. To start, we assume you’re running Xen v6.x or v7.x, and are logged into the Xen CLI as root. 1. Enable the SNMP daemon Enable the… Continue Reading
Manually purge data from Graylog 2.1 Rumi, March 1, 2021March 1, 2021 First aid: check which indices are present: curl http://localhost:9200/_cat/indices Then delete the oldest indices (you should not delete all) curl -XDELETE http://localhost:9200/graylog_1 curl -XDELETE http://localhost:9200/graylog_2 curl -XDELETE http://localhost:9200/graylog_3 Fix: You can then reduce the parameter elasticsearch_max_number_of_indices in /etc/graylog/server/server.conf to a value that fits your disk. Src: https://stackoverflow.com/questions/39502069/how-to-manually-purge-data-from-graylog-2-1 Continue Reading
Force Shutdown Xen VM Rumi, February 27, 2021 Instructions Disable High Availability (HA) so you don’t run into issues Log into the Xenserver host that is running your VM with issues via ssh or console via XenCenter Run the following command to list VMs and their UUIDs xe vm-list resident-on=<uuid_of_host> First you can try just the normal shutdown command with force xe… Continue Reading