- sysctl: name={{ item.name }} value={{ item.value }} sysctl_set=yes with_items: - { name: 'kernel.domainname', value: '{{ ansible_domain }}' } # Networking. See # https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt # Enable Spoof protection (reverse-path filter). Turn on Source # Address Verification in all interfaces to prevent some spoofing # attacks. - { name: 'net.ipv4.conf.default.rp_filter', value: 1 } - { name: 'net.ipv4.conf.all.rp_filter', value: 1 } # Enable TCP/IP SYN cookies to avoid TCP SYN flood attacks. We # rate-limit not only the default ICMP types 3, 4, 11 and 12 # (0x1818), but also types 0 and 8. See icmp(7). - { name: 'net.ipv4.tcp_syncookies', value: 1 } - { name: 'net.ipv4.icmp_ratemask', value: 6425 } - { name: 'net.ipv4.icmp_ratelimit', value: 1000 } # Disable paquet forwarding between interfaces (we are not a router). - { name: 'net.ipv4.ip_forward', value: 0 } - { name: 'net.ipv6.conf.all.forwarding', value: 0 } # Do not accept ICMP redirects (prevent MITM attacks). - { name: 'net.ipv4.conf.all.accept_redirects', value: 0 } - { name: 'net.ipv6.conf.all.accept_redirects', value: 0 } # Do not send ICMP redirects (we are not a router). - { name: 'net.ipv4.conf.default.send_redirects', value: 0 } - { name: 'net.ipv4.conf.all.send_redirects', value: 0 } # Do not accept IP source route packets (we are not a router). - { name: 'net.ipv4.conf.all.accept_source_route', value: 0 } - { name: 'net.ipv6.conf.all.accept_source_route', value: 0 } # Log Martian Packets. - { name: 'net.ipv4.conf.all.log_martians', value: 1 } # Ignore ICMP broadcasts. - { name: 'net.ipv4.icmp_echo_ignore_broadcasts', value: 1 } # Ignore bogus ICMP errors. - { name: 'net.ipv4.icmp_ignore_bogus_error_responses', value: 1 }