In this tutorial, you will see how you can install PostgreSQL on Ubuntu 20.04.

1. Connect to your server and run system updates:

sudo apt update

2. After that, install the Postgres package together with a -contrib package that adds some additional utilities and functionality:

sudo apt install postgresql postgresql-contrib

3. Then make sure that the service is running:

sudo systemctl start postgresql.service

4. PostgreSQL uses a concept called “roles” to handle authorization and authentication, by default.

sudo -i -u postgres

5. So you can access the Postgres prompt with the command:

psql

It will log you into the PostgreSQL prompt, and you will be able to interact with the database management system.

To exit out of the PostgreSQL prompt, you can use this command:

\q

6. If you are logged in as the postgres account, you can create a new role by running:

createuser --interactive

Then you will need to enter the name of the new role and make the role as superuser.

7. Another default assumption of the Postgres authentication system is that each role used to log in will have a database with the same name that it can access.

This implies that if the user you established in the previous section is named, for example, test, the role will attempt to connect to a database named test by default. The createdb command can be used to construct the necessary database.

If you're logged in as the postgres account, you can use this command:

createdb test

If you want to use sudo for each command without switching from your normal account, you can use the following command:

sudo -u postgres createdb test

8. You'll need a Linux user with the same name as your Postgres role and database to log in with ident based authentication.

If you don't have a matching Linux user, use the adduser command to create one. You must do the following using a non-root account with sudo access (not as the postgres user):

sudo adduser test

9. Then the new account is created, you can either switch over and connect to the database by running these commands:

sudo -i -u sammy
psql

10. However, if you want your user to connect to a different database, you can do that by specifying the database:

psql -d postgres

11. After running that command, you can check your current connection information by running this command:

\conninfo

VPS Password Is Not Correct

If you cannot connect to your VPS with your current VPS password, or you forgot it, you can connect to our client area and reset your VPS root password. Here is a guide how to do it.

Unresponsive SSH Connection

If your SSH connection attempts are timing out or are being immediately rejected, then your SSH service might not be running, or your firewall might block SSH connections.

So you can connect to your VPS via Emergency Console.

How To Check SSH Status?

To check your SSH service status, you need to connect to your VPS and run one of these commands:

1) Ubuntu 16.04+, Debian 8+, CentOS 7+, etc:

sudo systemctl status sshd -l

2) CentOS 6:

sudo service sshd status

3) Ubuntu 14.04, Debian 7

sudo service ssh status

How To Restart SSH Service?

If the output shows that your SSH is not running, then try to restart your SSH:

sudo systemctl restart sshd

CentOS 6:

sudo service sshd restart

Ubuntu 14.04, Debian 7:

sudo service ssh restart

How To Check SSH Logs?

If it won't help, then check your VPS logs of SSH::

sudo journalctl -u sshd -u ssh

CentOS 6

less /var/log/secure

Ubuntu 14.04, Debian 7

less /var/log/auth.log

SSH Is Running On A Non-Standard Port

If SSH status is active, make sure on what port SSH service is running. Run netstat on your server to check which port is used by SSH. For this, you can use this command:

sudo netstat -plntu | grep ssh

By default, SSH service runs on 22 port, but if you see a different port, then try to connect to your VPS via SSH by using that port:

ssh username@IP_address -p port

The Same Port Is Used By More Than One Service

If SSH service is running on your VPS, but you still cannot connect through SSH, then check your logs, to make sure that another service is not bounded on the same port as SSH. If in the logs, you see this message:

Bind to port 22 on 0.0.0.0 failed: Address already in use.

Then it means that another service on your server is already using the same port that SSH binds to. So this is a reason why SSH you cannot connect to your VPS via SSH. There are some ways to solve this issue:

1) Bind SSH service to a different port:

Here is a guide how to do that.

2) Stop the other service:

Use netstat command to check which other process is using the same port (as an example, we use 22 port);

sudo netstat -plntu | grep :22

Then stop that process:

sudo systemctl stop some-other-service

sudo systemctl disable some-other-service

Or simply kill the process using the process ID listed next to the process name when you check processes with the command - netstat.

3) Change other service port to a different port:

Again use netstat command to find what service is bound to the same port. Then, change the configuration for that service to use a different port. Ater that, you need to restart SSH service.

Misconfigured Firewall Rules For SSH Service

If you can start the SSH service successfully, but your connections still time out or are rejected, then review your firewall rules. It might e that you have blocked SSH connection on your firewall.

To check that, you can review your current firewall ruleset:

sudo iptables-save # displays IPv4 rules

sudo ip6tables-save # displays IPv6 rules

Also, if you have configured on your VPS FirewallD or UFW, make sure if you are running either package with these commands:

sudo ufw status

sudo firewall-cmd --state

when the rules will be listed, make sure that your rule for SSH looks something like this:

-A INPUT -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW -j ACCEPT

The rule says that you allow SSH connection in your VPS.

Disabling Firewall Rules

Additionally, for some time, you might to disable the firewall on your VPS to be sure that it is not a reason why you cannot connect to your VPS via SSH.

Note 1: The disabled firewall increases the security risk on your VPS, so make sure that you will re-enable it after you investigate your firewall configuration.

1. To do that, you can create a backup of your VPS firewall rules:

sudo iptables-save > ~/iptables.txt

2. Then set the INPUT, FORWARD and OUTPUT packet policies as ACCEPT:

sudo iptables -P INPUT ACCEPT
sudo iptables -P FORWARD ACCEPT
sudo iptables -P OUTPUT ACCEPT

3. After that, you need to flush the nat table that is consulted when a packet that creates a new connection is encountered:

sudo iptables -t nat -F

4. further, you need to flush the mangle table too that is used for specialized packet alteration:

sudo iptables -t mangle -F

5. And additionally flush all the chains in the table:

sudo iptables -F

6. In the end, delete every non-built-in chain in the table:

sudo iptables -X.

Note 2: You might need to do all these steps with ip6tables command to flush your IPv6 rules.

Note 3: Do not miss to use a different name for the IPv6 rules file.

Rejected SSH Logins

If SSH is listening and accepting connections but is rejecting login attempts, you should check logs of rejected attempts.

Also, make sure that logins are not disabled for the root user. It can be checked with the command:

grep PermitRootLogin /etc/ssh/sshd_config

Note 4: If the value of the PermitRootLogin is no, then try logging in with another user. Or, set the value in /etc/ssh/sshd_config to yes. After that, you need to restart SSH, and try logging in as root again.

Follow these steps to install CyberPanel on Ubuntu or Enterprise-based distros.

1. Log into SSH.
2. Run the CyberPanel installation script:

   sh <(curl https://cyberpanel.net/install.sh || wget -O - https://cyberpanel.net/install.sh)

3. Type “1” and Enter to confirm installation.
4. Choose “1” to install CyberPanel with OpenLiteSpeed. Remember, you’ll need a LiteSpeed Enterprise license for the Enterprise version.
5. Choose “Y” to install “full service for CyberPanel” – PowerDNS server, Postfix mail transfer agent (MTA), and Pure-FTPd server.
6. Choose “N” to skip remote MySQL setup and continue with local MySQL server setup.
7. Choose the latest MySQL version unless you’ll be importing a database that requires a specific, older version.
8. Choose “s” to set an admin password.
9. Type and confirm your admin password.
10. Choose whether to install Memcached and its PHP extension. You can always install this later if you don’t need it right now.
11. Decide whether to install Redis and its PHP extension. Again, you can install this post-installation.
12. Choose whether to install WatchDog, currently in beta, which automatically reboots downed systems with software errors. If you’re on a production system and unsure about this, we recommend denying this. 
13. The installation may take up to ten minutes. Afterwards, save the auto-generated LiteSpeed WebAdmin console password and Rainloop Webmail admin password in a password manager. The admin username for each login is “admin.”
14. Ubuntu users must choose “N” when asked to reboot the system.
    
    CentOS, AlmaLinux, and other Enterprise-based distro users may select “Y” and continue to the next section.
15. (Ubuntu users) Due to Ubuntu-specific issues, you’ll need to stop and disable Firewalld:

    systemctl stop firewalld && systemctl disable firewalld

16. Restart the system:

    reboot

Contact CyberPanel developers directly regarding Ubuntu firewall issues.

Log into CyberPanel

The URL to access your CyberPanel installation in the web browser is:

https://your-server-hostname:8090

Username: admin

Password: the same password you set during initial setup.

The dashboard shows buttons for primary functions with system resource usage stats on the right.

The top-right options grant quick access to various CyberPanel user communities.

The sidebar on the left lists primary sections which expand to show additional options when clicked. 

Learning Your CyberPanel Installation

Here are some ideas to help you get started:

• Configure automatic CyberPanel backups
• Create SSL certificates for the CyberPanel panel domain name
• Create regular users to manage websites
• Create a WordPress site in just a few clicks

The terminal command below resets your CyberPanel admin password. A space is added at the beginning to prevent the password from showing in bash history. Furthermore, we recommend using a simple password to ensure the process works. After you login, change the admin password to a stronger one.

 adminPass password!

Log into OpenLiteSpeed WebAdmin Console

Manage LiteSpeed web server settings from the web interface at: 

https://your-server-hostname:7080

The username is “admin.”

To reset your LiteSpeed console password, open a terminal session and run the following command:

sudo /usr/local/lsws/admin/misc/admpass.sh 

Press Enter to reset the default user – “[admin].”

Enter and confirm the new password.

Log into Rainloop WebMail

Access the Rainloop webmail web interface at: 

https://your-server-hostname:8090/snappymail/?admin

The username is “admin.”

1. To reset the Rainloop admin password, edit the configuration file:

   nano /usr/local/lscp/cyberpanel/rainloop/data/_data_/_default_/configs/application.ini

2. Add the following:

   [security]
   admin_password = "12345"

3. Save the settings.
4. Login and change the password immediately.

During testing, we were unable to reset the Rainloop admin password in Ubuntu. Further research showed that many users have similar issues. Contact CyberPanel developers directly for additional assistance.

Don’t forget to regularly check for server updates.

Check out our Support Center to learn more about managing your cloud server.

This entry was posted in CyberPanel.

One of the first things you could do in case you feel the server/website and its tasks are running slowly is to simply check your server load, it could be done with the  following commands:

If you are not sure or you don't know, you can find out the number of processors using these commands:

grep processor /proc/cpuinfo | wc -l

nproc

These commands will show just a number of your processors on the server. For example 1, 2, 4 and etc

Now you can check the server load using the other commands:

uptime

cat /proc/loadavg

The result of this command is very simple, but you could notice some anomalies here. An example of the uptime command output:

The output of the command shows how long is your server is up, how many users are currently logged in, and the load average, which provides values of 1 minute, 5 minutes, and 15 minutes. Considering we have 1 processor, the load values seem normal and not out of the ordinary. However, if the load average would be something like 1.50, 2.23, 8.14, this could be identified as a potential issue. The 1.00 stands for 100% of CPU utilization. So if the values are 1.50, 2.23, 8.14, they could be read as follows:

• 1.50 meaning that the CPU is overloaded by 50% during the last 1 minute;
• 2.23 meaning that the CPU is overloaded by 123% during the last 5 minutes;
• 8.14 meaning that the CPU is overloaded by 714% during the last 15 minutes.

While 50% or even 123% in this short time could be acceptable, the 3rd value should raise a concern. However, seeing the values decreasing could translate that the 'issue' is disappearing. While if the load values were 8.14, 2.23, 1.50 this could say that the load is just increasing right now.

The load values could show a potential issue regarding the server being attacked. The server load can rise according to the requests/traffic your server receives, however it could not be related to attacks at all, so we should check further and the next step is network traffic.

In a Linux environment, we could use netstat. This command could help to monitor the network and identifying possible issues. Here are a few general commands:

The command shows the number of connections each IP has with the server. It helps to identify the IPs that are connecting to the server most often. A single IP could be accessing your server a few times. For example, if you host some online resources, it might be normal to receive multiple connections from the same IP, as some smaller companies or networks with a shared IP are accessing your online resource. So you should include these possibilities depending on your server. However, let's say that one IP has 100+ connections to your server, this might seem suspicious and you should recheck it.

netstat -ntu|awk '{print $5}'|cut -d: -f1 -s|sort|uniq -c|sort -nk1 -r

A few more netstat commands for general monitoring.

This command shows all the active connections to the server:

netstat -na

This command shows all the specific traffic(in example port :80) by IPs :

netstat -an | grep :80 | sort

This command shows the number of connections by IP via TCP and UDP ports:

netstat -anp |grep 'tcp\|udp' | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n

All these commands as well as other options that netstat provides can help you to identify if there is something incorrect on your server network.

Now let's say you visited your website and noticed it runs slowly, you get 5xx errors. You then access the server and notice it's responding slower than usual - this could be a moment you can start checking your server load first. It could confirm something is wrong if the load is heavy. Then you could check the connections to your server and perhaps identify that a few IPs are connecting to the server hundreds of times. If these IPs are unknown, this could be considered as an attack against your server.

The next phase should be mitigating the attacks. Here are a few methods on how to do that.

If you noticed an unknown IP or a few that are just generating connections to your server and you want to stop that, you can block it using iptables, for example:

iptables -A INPUT -s 111.11.1.1 -j DROP(or REJECT)

service iptables save

service iptables restart

More information about how to use iptables in this tutorial.

Another thing is if you stopped everything, but yet the server is slow, there could be many Apache processes stuck due to previous connection attempts, you may try to simply kill them all and then start the Apache freshly(this usually takes ups to a few minutes or quicker):

killall -KILL httpd

service httpd start

Note. This article is a simple way to check and try to find out if your server is under attack when you have any suspicions. There are many other tools, methods, and procedures that you can use as well. This is just something to get you started.

exim -bpc

2. Print a listing of the messages in the queue (time queued, size, message-id, sender, recipient):

exim -bp

3. Print a summary of messages in the queue (count, volume, oldest, newest, domain, and totals):

exim -bp | exiqsumm

4. Print what Exim is doing right now:

exiwhat

5. Testing how e-mail address is pointed:

exim -bt mail@domain.com

6. Run a pretend SMTP transaction from the command line, as if it were coming from the given IP address. This will display Exim's checks, ACLs, and filters as they are applied. The message will NOT actually be delivered:

exim -bh XXX.XXX.XX.XX

7. Display all of Exim's configuration settings:

exim -bP

Searching the queue with exiqgrep

Exim includes a utility that is quite nice for grepping through the queue, called exiqgrep.

1. Use -f to search the queue for messages from a specific sender:

exiqgrep -f @domain

2. Use -r to search the queue for messages for a specific recipient/domain:

exiqgrep -r @domain

3. Use -o to print messages older than the specified number of seconds. For example, messages older than 1 day:

exiqgrep -o 86400 [...]

4. Use -y to print messages that are younger than the specified number of seconds. For example, messages less than an hour old:

exiqgrep -y 3600 [...]

5. Use -s to match the size of a message with a regex. For example, 700-799 bytes:

exiqgrep -s '^7..$' [...]

Use -z to match only frozen messages, or -x to match only unfrozen messages. There are also a few flags that control the display of the output.

6. Use -i to print just the message-id as a result of one of the above two searches:

exiqgrep -i [ -r | -f ] ...

7. Use -c to print a count of messages matching one of the above searches:

exiqgrep -c ...

8. Print just the message-id of the entire queue:

exiqgrep -i

Managing the queue

1. Start a queue run

exim -q -v

2. Start a queue run for just local deliveries:

exim -ql -v

3. Remove a message from the queue:

exim -Mrm <message-id> [ <message-id> ... ]

4. Freeze a message:

exim -Mf <message-id> [ <message-id> ... ]

5. Throw a message:

exim -Mt <message-id> [ <message-id> ... ]

6. Deliver a message, whether it's frozen or not, whether the retry time has been reached or not:

exim -M <message-id> [ <message-id> ... ]

7. Deliver a message, but only if the retry time has been reached:

exim -Mc <message-id> [ <message-id> ... ]

8. Force a message to fail and bounce as "cancelled by administrator":

exim -Mg <message-id> [ <message-id> ... ]

9. Remove all frozen messages:

exiqgrep -z -i | xargs exim -Mrm

10. Remove all messages older than five days (86400 * 5 = 432000 seconds):

exiqgrep -o 432000 -i | xargs exim -Mrm

11. Freeze all queued mail from a given sender:

exiqgrep -i -f luser@example.tld | xargs exim -Mf

12. View a message's headers:

exim -Mvh <message-id>

13. View a message's body:

exim -Mvb <message-id>

14. View a message's logs:

exim -Mvl <message-id>

Digging Into Exim Mail Logs With Exigrep

One single mail transaction will span multiple lines in the file, and not every line will have the search string you are looking for. The exigrep command works around this problem by finding your search string in transactions, and then helpfully gathering every log entry into separate, complete transactions.

1. Search for messages sent from a particular IP address:

exigrep '<= .* \[12.34.56.78\] ' /path/to/exim_log

2. search for messages sent to a particular IP address:

exigrep '=> .* \[12.34.56.78\] ' /path/to/exim_log

This is how you search for outgoing messages with the “=>” symbol that are sent to “mail@domain.com”. The pipe to grep for the “<=” symbol will only match lines containing information on the sender, the From address, the sender’s IP address, the message size, the message ID, and the subject line if you have enabled logging the subject.

3. Generate and display Exim stats from a logfile:

eximstats /path/to/exim_mainlog

4. Same as above, with less verbose output:

eximstats -ne -nr -nt /path/to/exim_mainlog

5.To delete all queued messages containing a certain string in the body:

grep -lr 'a certain string' /var/spool/exim/input/ | \sed -e 's/^.*\/\([a-zA-Z0-9-]*\)-[DH]$/\1/g' | xargs exim -Mrm

-- http://www.exim.org/
-- http://www.exim.org/docs.html

Requirements

* DirectAdmin license * One of the following OS templates installed: CentOS 7, CentOS 8, Debian 8, Debian 9, Debian 10, Debian 11

Installation

DirectAdmin installation is very simply you simply, here are the basic steps:

1. Connect to your Linux server via SSH;
2. Enter the following installation command:

bash <(curl -Ss https://www.directadmin.com/setup.sh || wget -O - https://www.directadmin.com/setup.sh)

3. Once the command is executed, a download will start, shortly after you will be prompted to enter your license key. Enter your DirectAdmin license key and proceed.

That is it, once the installation is complete, DirectAdmin can be accessed at http://server.ip.address:2222.

Important. Use the Admin username/password provided by the file: /usr/local/directadmin/scripts/setup.txt