148 lines
4.0 KiB
Markdown
148 lines
4.0 KiB
Markdown
---
|
||
title: Preparing your machine
|
||
menu:
|
||
docs:
|
||
weight: 10
|
||
parent: admin
|
||
---
|
||
|
||
If you are setting up a fresh machine, it is recommended that you secure it first. Assuming that you are running **Ubuntu 20.04**:
|
||
|
||
## Do not allow password-based SSH login (keys only)
|
||
|
||
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.
|
||
|
||
Edit `/etc/ssh/sshd_config` and find `PasswordAuthentication`. Make sure it’s uncommented and set to `no`. If you made any changes, restart sshd:
|
||
|
||
```bash
|
||
systemctl restart ssh.service
|
||
```
|
||
|
||
## Update system packages
|
||
|
||
```bash
|
||
apt update && apt upgrade -y
|
||
```
|
||
|
||
## Install fail2ban so it blocks repeated login attempts
|
||
|
||
First, install fail2ban:
|
||
|
||
```bash
|
||
apt install fail2ban
|
||
```
|
||
|
||
Edit `/etc/fail2ban/jail.local` and put this inside:
|
||
|
||
```text
|
||
[DEFAULT]
|
||
destemail = your@email.here
|
||
sendername = Fail2Ban
|
||
|
||
[sshd]
|
||
enabled = true
|
||
port = 22
|
||
|
||
[sshd-ddos]
|
||
enabled = true
|
||
port = 22
|
||
```
|
||
|
||
Finally, restart fail2ban:
|
||
|
||
```bash
|
||
systemctl restart fail2ban
|
||
```
|
||
|
||
## Install a firewall and only allow SSH, HTTP and HTTPS ports
|
||
|
||
First, install iptables-persistent. During installation, it will ask you if you want to keep the current rules–decline.
|
||
|
||
```bash
|
||
apt install -y iptables-persistent
|
||
```
|
||
|
||
Edit `/etc/iptables/rules.v4` and put this inside:
|
||
|
||
```text
|
||
*filter
|
||
|
||
# Allow all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0
|
||
-A INPUT -i lo -j ACCEPT
|
||
-A INPUT ! -i lo -d 127.0.0.0/8 -j REJECT
|
||
|
||
# Accept all established inbound connections
|
||
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
|
||
|
||
# Allow all outbound traffic - you can modify this to only allow certain traffic
|
||
-A OUTPUT -j ACCEPT
|
||
|
||
# Allow HTTP and HTTPS connections from anywhere (the normal ports for websites and SSL).
|
||
-A INPUT -p tcp --dport 80 -j ACCEPT
|
||
-A INPUT -p tcp --dport 443 -j ACCEPT
|
||
|
||
# Allow SSH connections
|
||
# The -dport number should be the same port number you set in sshd_config
|
||
-A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT
|
||
|
||
# Allow ping
|
||
-A INPUT -p icmp -m icmp --icmp-type 8 -j ACCEPT
|
||
|
||
# Allow destination unreachable messages, especially code 4 (fragmentation required) is required or PMTUD breaks
|
||
-A INPUT -p icmp -m icmp --icmp-type 3 -j ACCEPT
|
||
|
||
# Log iptables denied calls
|
||
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7
|
||
|
||
# Reject all other inbound - default deny unless explicitly allowed policy
|
||
-A INPUT -j REJECT
|
||
-A FORWARD -j REJECT
|
||
|
||
COMMIT
|
||
```
|
||
|
||
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:
|
||
|
||
```bash
|
||
iptables-restore < /etc/iptables/rules.v4
|
||
```
|
||
|
||
If your server is also reachable over IPv6, edit `/etc/iptables/rules.v6` and add this inside:
|
||
```text
|
||
*filter
|
||
|
||
# Allow all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0
|
||
-A INPUT -i lo -j ACCEPT
|
||
-A INPUT ! -i lo -d ::1/128 -j REJECT
|
||
|
||
# Accept all established inbound connections
|
||
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
|
||
|
||
# Allow all outbound traffic - you can modify this to only allow certain traffic
|
||
-A OUTPUT -j ACCEPT
|
||
|
||
# Allow HTTP and HTTPS connections from anywhere (the normal ports for websites and SSL).
|
||
-A INPUT -p tcp --dport 80 -j ACCEPT
|
||
-A INPUT -p tcp --dport 443 -j ACCEPT
|
||
|
||
# Allow SSH connections
|
||
# The -dport number should be the same port number you set in sshd_config
|
||
-A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT
|
||
|
||
# Allow ping
|
||
-A INPUT -p icmpv6 -j ACCEPT
|
||
|
||
# Log iptables denied calls
|
||
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7
|
||
|
||
# Reject all other inbound - default deny unless explicitly allowed policy
|
||
-A INPUT -j REJECT
|
||
-A FORWARD -j REJECT
|
||
|
||
COMMIT
|
||
```
|
||
Similar to the IPv4 rules, you can load it manually like this:
|
||
```bash
|
||
ip6tables-restore < /etc/iptables/rules.v6
|
||
```
|