97 lines
2.5 KiB
Markdown
97 lines
2.5 KiB
Markdown
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---
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title: Preparing your machine
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menu:
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docs:
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weight: 10
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parent: admin
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---
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If you are setting up a fresh machine, it is recommended that you secure it first. Assuming that you are running **Ubuntu 18.04**:
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## Do not allow password-based SSH login \(keys only\)
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First make sure you are actually logging in to the server using keys and not via a password, otherwise this will lock you out. Many hosting providers support uploading a public key and automatically set up key-based root login on new machines for you.
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Edit `/etc/ssh/sshd_config` and find `PasswordAuthentication`. Make sure it’s uncommented and set to `no`. If you made any changes, restart sshd:
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## Update system packages
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```bash
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apt update && apt upgrade -y
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```
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## Install fail2ban so it blocks repeated login attempts
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Edit `/etc/fail2ban/jail.local` and put this inside:
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```text
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[DEFAULT]
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destemail = your@email.here
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sendername = Fail2Ban
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[sshd]
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enabled = true
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port = 22
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[sshd-ddos]
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enabled = true
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port = 22
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```
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Finally restart fail2ban:
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```bash
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systemctl restart fail2ban
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```
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## Install a firewall and only whitelist SSH, HTTP and HTTPS ports
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First, install iptables-persistent. During installation it will ask you if you want to keep current rules–decline.
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```bash
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apt install -y iptables-persistent
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```
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Edit `/etc/iptables/rules.v4` and put this inside:
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```text
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*filter
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# Allow all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0
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-A INPUT -i lo -j ACCEPT
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-A INPUT ! -i lo -d 127.0.0.0/8 -j REJECT
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# Accept all established inbound connections
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-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
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# Allow all outbound traffic - you can modify this to only allow certain traffic
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-A OUTPUT -j ACCEPT
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# Allow HTTP and HTTPS connections from anywhere (the normal ports for websites and SSL).
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-A INPUT -p tcp --dport 80 -j ACCEPT
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-A INPUT -p tcp --dport 443 -j ACCEPT
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# Allow SSH connections
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# The -dport number should be the same port number you set in sshd_config
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-A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT
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# Allow ping
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-A INPUT -p icmp -m icmp --icmp-type 8 -j ACCEPT
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# Log iptables denied calls
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-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7
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# Reject all other inbound - default deny unless explicitly allowed policy
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-A INPUT -j REJECT
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-A FORWARD -j REJECT
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COMMIT
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```
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With iptables-persistent, that configuration will be loaded at boot time. But since we are not rebooting right now, we need to load it manually for the first time:
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```bash
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iptables-restore < /etc/iptables/rules.v4
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```
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