# ip forwarding (default = 0)
net.ipv4.ip_forward = 0
# filtering by source IP address (default = 0)
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
# ICMP-messages for routes (default = 1)
net.ipv4.conf.default.accept_redirects = 0
# enable secure redirects (default = 1)
net.ipv4.conf.all.secure_redirects = 1
# forbid sender to define route (default = 0)
net.ipv4.conf.default.accept_source_route = 0
# Invalidate / discard packets when the route for outbound
# traffic differs from the route of incoming traffic
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.all.rp_filter = 1