Linux whois command is used to find who owns a domain or IP address.
To see information about a domain, use
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whois DOMAIN_NAME_HERE |
Example
To find information about an IP address, use
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whois IP_ADDR_HERE |
Example
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To see if a web site have HTTP/2 enabled, you can run
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curl -sI SITE_URL_HERE -o /dev/null -w '%{http_version}\n' |
If you see 2, the site have HTTP/2 enabled.
Example
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boby@sok-01:~$ curl -sI https://serverok.in/ -o /dev/null -w '%{http_version}\n' 2 boby@sok-01:~$ |
Here is a site with no HTTP/2
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boby@sok-01:~$ curl -sI http://ok.serverok.in/ -o /dev/null -w '%{http_version}\n' 1.1 boby@sok-01:~$ |
wget is used to download files. When you use wget to run cronjob, it create lot of files. To avoid this, you can replace wget command with curl.
If you want to use wget, you can use -O option, that speicify file to save. You can use -O /dev/stdout, so downloaded file content will be written to stdout.
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wget -O /dev/stdout http://checkip.amazonaws.com |
You can use -q to hide the download progres message (quite).
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wget -q -O /dev/stdout http://checkip.amazonaws.com |
-O /dev/stdout can be replaced with
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-O - |
Or
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-O- |
Example
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wget -qO- http://checkip.amazonaws.com |
See wget
It is better to make web site available with one URL. Many sites work with both wwww and non-www (naked domain) urls.
Using www or non-www is personal choice. One advantage of using wwww for URL is when you have lot of sub domains. If you use non-www url, cookies set by the domain will be available to sub domains. This will increase bandwidth usage as cookie need to be sent with every request browser make to web server.
If you are using Apache web server, you can redirect wwww to non-www url by adding following code in .htaccess file
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RewriteEngine On RewriteCond %{HTTP_HOST} ^www.yourdomain.com [NC] RewriteRule ^(.*)$ https://yourdomain.com$1 [L,R=301] |
Redirect non-www to www
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RewriteEngine On RewriteCond %{HTTP_HOST} ^yourdomain.com [NC] RewriteRule ^(.*)$ https://www.yourdomain.com$1 [L,R=301] |
If you use Nginx, it is better create a server entry for www URL, then set a redirect
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server { server_name www.yourdomain.com; return 301 $scheme://yourdomain.com$request_uri; } |
If you want to use same server entry for www and non-www, add following code to nginx server entry for the web site.
Redirect www domain to non-www
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if ( $host != 'yourdomain.com' ) { return 301 https://yourdomain.com$request_uri; } |
If you use custom ports, use
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if ( $host != 'yourdomain.com' ) { return 301 https://yourdomain.com:$server_port$request_uri; } |
Redirect Naked Domain to www
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if ( $host != 'www.serverok.in' ) { return 301 https://serverok.in$request_uri; } |
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By default Squid proxy only allow out going connection to white listed ports that are used commonly. When you visit a site with non standard ports with Squid proxy, it won’t work. To fix this, edit squid configuration file
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vi /etc/squid/squid.conf |
Find
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acl SSL_ports port 443 acl Safe_ports port 80 # http acl Safe_ports port 21 # ftp acl Safe_ports port 443 # https acl Safe_ports port 70 # gopher acl Safe_ports port 210 # wais acl Safe_ports port 1025-65535 # unregistered ports acl Safe_ports port 280 # http-mgmt acl Safe_ports port 488 # gss-http acl Safe_ports port 591 # filemaker acl Safe_ports port 777 # multiling http |
Replace with
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acl SSL_ports port 1-65535 acl Safe_ports port 1-65535 |
Restart squid with
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systemctl restart squid |
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You can restart services on xampp linux using
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/opt/lampp/lampp |
To restart, use
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/opt/lampp/lampp restart |
Here are other available options
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root@ip-172-31-36-153:~# /opt/lampp/lampp --help Usage: lampp <action> start Start XAMPP (Apache, MySQL and eventually others) startapache Start only Apache startmysql Start only MySQL startftp Start only ProFTPD stop Stop XAMPP (Apache, MySQL and eventually others) stopapache Stop only Apache stopmysql Stop only MySQL stopftp Stop only ProFTPD reload Reload XAMPP (Apache, MySQL and eventually others) reloadapache Reload only Apache reloadmysql Reload only MySQL reloadftp Reload only ProFTPD restart Stop and start XAMPP security Check XAMPP's security enablessl Enable SSL support for Apache disablessl Disable SSL support for Apache backup Make backup file of your XAMPP config, log and data files oci8 Enable the oci8 extenssion panel Starts graphical XAMPP control panel root@ip-172-31-36-153:~# |
To remove SSH private key passphrase, run
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ssh-keygen -p -f SSH_PRIVATE_KEY_FILE |
Example
Method 2
You can use OpenSSL to remove passphase with
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openssl rsa -in PRIVATE_KEY_WITH_PW.key -out PRIVATE_KEY_NO_PW.key |
See SSH
To always force webmail to use HTTP on VeataCP, edit file
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vi /etc/roundcube/defaults.inc.php |
Find
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$rcmail_config['force_https'] = false; |
Replace with
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$rcmail_config['force_https'] = true; |
To run Prometheus Node Exporter on custom port, use
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/usr/local/bin/node_exporter --web.listen-address=:9101 |
Here is systemctl service script i used
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[root@cdn 1945]# cat /etc/systemd/system/node_exporter.service [Unit] Description=Node Exporter Wants=network-online.target After=network-online.target [Service] User=node_exporter Group=node_exporter Type=simple ExecStart=/usr/local/bin/node_exporter --web.listen-address=:9101 [Install] WantedBy=multi-user.target [root@cdn 1945]# |
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Prometheus is used an open source software, that can collect metrics and alerting.
You can download latest version oof Prometheus from
https://prometheus.io/download/
Create a user
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useradd --no-create-home --system --shell /bin/false prometheus |
Download and Install prometheus
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cd /usr/local/src wget https://github.com/prometheus/prometheus/releases/download/v2.14.0/prometheus-2.14.0.linux-amd64.tar.gz tar xvf prometheus-2.14.0.linux-amd64.tar.gz cd prometheus-2.14.0.linux-amd64/ mv prometheus /usr/local/bin/ mv promtool /usr/local/bin/ mkdir /etc/prometheus mkdir /var/lib/prometheus mv consoles /etc/prometheus mv console_libraries /etc/prometheus mv prometheus.yml /etc/prometheus chown prometheus:prometheus /etc/prometheus chown prometheus:prometheus /var/lib/prometheus |
Create a service file
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vi /etc/systemd/system/prometheus.service |
Add following content
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[Unit] Description=Prometheus Wants=network-online.target After=network-online.target [Service] User=prometheus Group=prometheus Type=simple ExecStart=/usr/local/bin/prometheus \ --config.file /etc/prometheus/prometheus.yml \ --storage.tsdb.path /var/lib/prometheus/ \ --web.console.templates=/etc/prometheus/consoles \ --web.console.libraries=/etc/prometheus/console_libraries [Install] WantedBy=multi-user.target |
Enable prometheus to start on boot
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systemctl enable prometheus |
Start prometheus
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systemctl start prometheus systemctl status prometheus |
Prometheus runs on port 9090, you can access promethus at
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http://YOUR_SERVER_IP:9090/graph |
It will look like
Prometheus have some basic graphing features, but you can’t use it for monitoring. To create dash board and monitor, you need to use grafana.
Node Exporter is used to collect data from servers. All monitored servers need Node Exporter installed.
Lets create a user for Node Exporter to run
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useradd --no-create-home --system --shell /bin/false node_exporter |
Install Node Exporter
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cd /usr/local/src wget https://github.com/prometheus/node_exporter/releases/download/v0.18.1/node_exporter-0.18.1.linux-amd64.tar.gz tar xvf node_exporter-0.18.1.linux-amd64.tar.gz cd /usr/local/src/node_exporter-0.18.1.linux-amd64/ mv node_exporter /usr/local/bin/ |
Create a systemd service file for node exporter
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vi /etc/systemd/system/node_exporter.service |
Add
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[Unit] Description=Node Exporter Wants=network-online.target After=network-online.target [Service] User=node_exporter Group=node_exporter Type=simple ExecStart=/usr/local/bin/node_exporter [Install] WantedBy=multi-user.target |
Enable and start Node Exporter
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systemctl enable node_exporter systemctl start node_exporter systemctl status node_exporter |
Node Exporter run on port 9100 and expose system metrics on url
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http://SERVER_IP:9100/metrics |
Once Node Exporter installed on a server, you need to tell Prometheus to get data from the Node Exporter you just installed. To do this, edit Prometheus configuration file.
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vi /etc/prometheus/prometheus.yml |
Add following
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- job_name: 'node_exporter' scrape_interval: 5s static_configs: - targets: ['SERVER_IP:9100'] |
To monitor multiple servers, you can dd more servers in targets line. Here is an example config
https://gist.github.com/serverok/83a622e7577da36384f87fe60c9930af/raw
Restart prometheus
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systemctl restart prometheus |
Grafana is used to visualise data collected by Prometheus. You can download Grafana from
https://grafana.com/grafana/download
Grafana offers free cloud hosted version with some limitation (1 user, 5 dashboards). Free version is suitable if you are getting started and don’t want to install your own. You can signup for cloud hosted version at
If you decide to install your own Grafana, you can run
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cd /usr/local/src wget https://dl.grafana.com/oss/release/grafana_6.4.4_amd64.deb dpkg -i grafana_6.4.4_amd64.deb |
Enable and start grafana
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systemctl enable grafana-server systemctl start grafana-server systemctl status grafana-server |
If you did your own install, grafana runs on port 3000. To access, use url
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http://SERVER_IP:3000/login |
Default username and passwords are “admin”. Once logged in you will be asked to set password for grafana admin user.
Before you can use Grafana, you need to set a data source and create dash board. In our case, data source is prometheus. To connect Grafana to your Prometheus insallation, go to Settings > Data Sources
On next page, select Prometheus
On next page, for URL, enter http://PROMETHUS_SERVER_IP:9090, scroll down, click on “Save & Test” button. If grafana can connect to your prometheus installation, you should see success message with “Data source is working”. If not, you need to check your firewall rules.
Grafana displays data in dash boards. You can create your own or use pre existing dash boards. You can find pre-made dash boards at
https://grafana.com/grafana/dashboards
On my grafana installation, i used dashboard
https://grafana.com/grafana/dashboards/11074
To add this dash board to your Grafana, click on the + button, then select Import. On next screen, you can enter ID for the dash board you need to import. In this case 11074. Click “Load” button to import the dash board.
Here is a dash board for one of the server
You can edit Panels in grafana dash board to see how it is created. You can create a new dash board with panel you need. This way your dashboards only show required information.
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