## TCP/IP stack hardening 

# Protects against time-wait assassination. It drops RST packets for sockets in the time-wait state.
net.ipv4.tcp_rfc1337=1

# Disables ICMP redirect acceptance.
net.ipv4.conf.all.accept_redirects=0
net.ipv4.conf.default.accept_redirects=0
net.ipv4.conf.all.secure_redirects=0
net.ipv4.conf.default.secure_redirects=0
net.ipv6.conf.all.accept_redirects=0
net.ipv6.conf.default.accept_redirects=0

# Disables ICMP redirect sending.
net.ipv4.conf.all.send_redirects=0
net.ipv4.conf.default.send_redirects=0

# Ignores ICMP requests.
net.ipv4.icmp_echo_ignore_all=1

# Enables TCP syncookies.
net.ipv4.tcp_syncookies=1

# Disable source routing.
net.ipv4.conf.all.accept_source_route=0
net.ipv4.conf.default.accept_source_route=0