A ha! First step in setting my home lab!
In this post I will explain how to install and configure, in a fast and easy way, a firewall on a Linux Debian 10 system, to allow only two things:
- web browsing traffic to the Internet
- Incoming SSH connections
So, let's begin. We will
- Set a static IP for our host
- Install UFW as firewall and configure it
Setting a static IP for our host
For further configuration we will change our network address to be a static one. In my recent installed Debian 10 system the ip address is dinamic. In my particular case the IP asigned by the router is the 192.168.0.19
We can verify the IP addresses with the command
$ ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 2c:41:38:ae:bc:14 brd ff:ff:ff:ff:ff:ff inet 192.168.0.19/24 brd 192.168.0.255 scope global dynamic noprefixroute eno1 valid_lft 587730sec preferred_lft 587730sec inet6 fe80::2e41:38ff:feae:bc14/64 scope link noprefixroute valid_lft forever preferred_lft forever
So to et 192.168.0.10 as our IP we will add the following lines to the
/etc/network/interfaces to s.
# Static IP for our Ethernet interface iface eth0 inet static address 192.168.0.10 netmask 255.255.255.0 gateway 192.168.0.1 dns-search mundo-R.com dns-nameserver 126.96.36.199 dns-nameserver 188.8.131.52
Notice that as DNS name servers and search values I have set those told by my Internet provider, and normally set in
/etc/resolv.conf file in a default dynamic IP address assignation
And this line in /etc/hosts (
hppro3300 is my host name and
ciges.net my domain name)
192.168.0.10 hppro3300.ciges.net hppro3300
Setting up a firewall with UFW to allow outgoing traffic only in the port 80
UFW, or "Uncomplicated Firewall", is a simple interface to iptables, so it should be an easy way to set our firewall.
So, first, we install (as user
root) the firewall and Gufw, a graphical interface to configure it.
apt install ufw gufw
After installation the firewall is enabled by default. The commands to set the rules to allow outgoing HTTP traffic and ingoing connections using SSH will be:
ufw default deny incoming ufw default deny outgoing ufw allow out http ufw allow out https ufw allow out ssh ufw allow out dns ufw allow in ssh
They are clear:
- first we deny everything
- then allow outgoing traffic for HTTP, HTTPS, DNS and SSH (ports 80, 443, 53 and 22). DNS (port 53) is needed!, if we dont allow it then no URL will be found 🙂
- allow SSH connections to our host to allow opening terminals from another computers in our network
To verify our firewall status the command line will be:
$ ufw status verbose Status: active Logging: on (low) Default: deny (incoming), deny (outgoing), disabled (routed) New profiles: skip To Action From -- ------ ---- 22/tcp ALLOW IN Anywhere 22/tcp (v6) ALLOW IN Anywhere (v6) 80/tcp ALLOW OUT Anywhere 443/tcp ALLOW OUT Anywhere 22/tcp ALLOW OUT Anywhere 53 (DNS) ALLOW OUT Anywhere 80/tcp (v6) ALLOW OUT Anywhere (v6) 443/tcp (v6) ALLOW OUT Anywhere (v6) 22/tcp (v6) ALLOW OUT Anywhere (v6) 53 (DNS (v6)) ALLOW OUT Anywhere (v6)
We could easily enable and disable the firewall with the commands:
ufw enable ufw disable
I have installed a graphical interface, but I prefer to use the command line when it's not too hard, as in this case 🙂
If we run Gufw we can see the rules recently set, as shown here (the screenshot shows the interface in Spanish, but it's clear anyway)
Well, it's done!
Next step, setting an HTTP Proxy with user authentication, but that is another story ...
- Deploying a DevOps playground at home with Debian Linux and VirtualBox
- Installing a firewall on a Linux host, quick and dirty, with UFW
- Protecting my public Linux host from brute force SSH attacks