source setup/functions.sh # load our functions # Base system configuration. apt-get -qq update apt-get -qq -y upgrade # Install basic utilities. apt_install python3 python3-pip wget curl bind9-host # Turn on basic services: # # ntp: keeps the system time correct # # fail2ban: scans log files for repeated failed login attempts and blocks the remote IP at the firewall # # These services don't need further configuration and are started immediately after installation. apt_install ntp fail2ban if [ -z "$DISABLE_FIREWALL" ]; then # Turn on the firewall. First allow incoming SSH, then turn on the firewall. # Other ports will be opened at the point where we set up those services. # # Various virtualized environments like Docker and some VPSs don't provide # a kernel that supports iptables. To avoid error-like output in these cases, # let us disable the firewall. apt_install ufw ufw_allow ssh; ufw --force enable; fi # Resolve DNS using bind9 locally, rather than whatever DNS server is supplied # by the machine's network configuration. We do this to ensure that DNS queries # that *we* make (i.e. looking up other external domains) perform DNSSEC checks. # We could use Google's Public DNS, but we don't want to create a dependency on # Google per our goals of decentralization. bind9, as packaged for Ubuntu, has # DNSSEC enabled by default via "dnssec-validation auto". # # So we'll be running bind9 bound to 127.0.0.1 for locally-issued DNS queries # and nsd bound to the public ethernet interface for remote DNS queries asking # about our domain names. nsd is configured in dns.sh. # # About the settings: # # * RESOLVCONF=yes will have bind9 take over /etc/resolv.conf to tell # local services that DNS queries are handled on localhost. # * Adding -4 to OPTIONS will have bind9 not listen on IPv6 addresses # so that we're sure there's no conflict with nsd, our public domain # name server, on IPV6. # * The listen-on directive in named.conf.options restricts bind9 to # binding to the loopback interface instead of all interfaces. apt_install bind9 tools/editconf.py /etc/default/bind9 \ RESOLVCONF=yes \ "OPTIONS=\"-u bind -4\"" if ! grep -q "listen-on " /etc/bind/named.conf.options; then # Add a listen-on directive if it doesn't exist inside the options block. sed -i "s/^}/\n\tlisten-on { 127.0.0.1; };\n}/" /etc/bind/named.conf.options fi service bind9 restart