How To - Debian - Getting Started & Simple Security
Setting your hostname
echo "hostname" > /etc/hostname
hostname -F /etc/hostname
Update /etc/hosts
127.0.0.1 localhost.localdomain localhost
11.22.33.44 hostname.domain.com hostname
Setting the timezone
dpkg-reconfigure tzdata
Editing /etc/apt/sources.list
Use this tool to generate the right sources.list file for you.
Install software updates
apt-get update
apt-get upgrade
alternately if it says packages have been held back you can do apt-get dist-upgrade.
To add a new user
adduser example
Add that user as an admin
usermod -a -G sudo example
Changing SSH port and prevent root login
nano /etc/ssh/sshd_config
—
Port 2200
—
PermitRootLogin no
Adding firewall rules
sudo nano /etc/iptables.firewall.rules
—
*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 -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 connections from anywhere (the normal ports for websites).
-A INPUT -p tcp --dport 80 -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 --icmp-type echo-request -j ACCEPT
# Log iptables denied calls
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7
# Drop all other inbound - default deny unless explicitly allowed policy
-A INPUT -j DROP
-A FORWARD -j DROP
COMMIT
—
sudo iptables-restore < /etc/iptables.firewall.rules
Setting the firewall to set on restart
sudo nano /etc/network/if-pre-up.d/firewall
---
#!/bin/sh
/sbin.iptables-restore < /etc/iptables.firewall.rules
---
sudo chmod +x /etc/network/if-pre-up.d/firewall
Installing Fail2Ban
sudo apt-get install fail2ban
Conclusion
This is one of many parts that will be produced. If you have a specific question or topic let us know in the comment section!
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