Setting up a Server

Logistics

 2021/05/15 

Initial Server Setup

We chose “use ssh keys to log in” when creating the server, so we need to first get our root password by “reset root password”. Next time when you log in, you will be prompted to change password.
log into server ssh root@your_server_ip. Passphrase set when creating ssh keys are needed.

Check currently available users with cat /etc/passwd
Add a new user with adduser <username>

If a wrong user is added accidentally, delete it with deluser <username>
Grant this newly added user sudo privilege by “appending” it to sudo “Group” usermod -aG sudo <username>

We can log in with the following two ways:

Enabling ssh password login:
1. go to /etc/ssh/sshd_config and change PasswordAuthentication no to PasswordAuthentication yes.
2. Restart the service after editing sudo service ssh restart.
Continue use SSH Authentication:

We want to copy the keys with the correct ownership and permissions, so use rsync --archive --chown=sammy:sammy ~/.ssh /home/sammy (Replace “sammy” with your username)
- explains what –archive does
- --chown=USER:GROUP forces all files to be owned by USER with group GROUP
- be sure that the source directory (~/.ssh) does not include a trailing slash (check to make sure you are not using ~/.ssh/) If you accidentally add a trailing slash to the command, rsync will copy the contents of the root account’s ~/.ssh directory to the sudo user’s home directory instead of copying the entire ~/.ssh directory structure.

We can now log in as the newly added user <username>@your_server_ip

Before everything, you should check IPV6 is enabled by going to nano /etc/default/ufw and check IPV6=yes.

Set up a default profile to deny all incoming and allow all outgoing.
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ufw default deny incoming
ufw default allow outgoing
This is enough for a PC but not enough for a server. We would need to allow ssh, HTTP, and HTTPS.
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ufw allow ssh
ufw allow http
ufw allow https
The Firewall will then allow traffic from the default ports specified by these applications. For example, ssh uses port 22, so ufw allow ssh is equivalent to ufw allow 22.
Enable and check firewall’s status:
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ufw enable
ufw status verbose