/etc/sysctl.conf
# Forwarding deaktivieren
net.ipv4.ip_forward = 0
net.ipv6.conf.all.forwarding = 0
# Packet Redirect deaktivieren
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
# Routed Packets nicht akzeptieren
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0
net.ipv6.conf.all.accept_source_route = 0
net.ipv6.conf.default.accept_source_route = 0
# ICMP Redirects nicht akzeptieren
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv6.conf.all.accept_redirects = 0
net.ipv6.conf.default.accept_redirects = 0
# Secure ICMP Redirects nicht akzeptieren
net.ipv4.conf.all.secure_redirects = 0
net.ipv4.conf.default.secure_redirects = 0
# Suspicious packets müssen geloggt werden
net.ipv4.conf.all.log_martians = 1
net.ipv4.conf.default.log_martians = 1
# Broadcast ICMP Requests müssen ignoriert werden
net.ipv4.icmp_echo_ignore_broadcasts = 1
# bogus ICMP responses müssen ignoriert werden
net.ipv4.icmp_ignore_bogus_error_responses = 1
# Reverse Path Filtering aktivieren
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
# TCP SYN Cookies müssen aktivieren werden
net.ipv4.tcp_syncookies = 1
# IPv6 router advertisements deaktivieren
net.ipv6.conf.all.accept_ra = 0
net.ipv6.conf.default.accept_ra = 0