Lock down new server network

iptables.md

# Allow localhost traffic
iptables -A INPUT -i lo -j ACCEPT

# INVALID type packets should be DROPped regardless of source.
iptables -A INPUT -m state --state INVALID -j DROP

# Allow traffic for related/established connections already running
iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

# Allow all new connections/traffic from the local subnet you're on 
# (10.20.30.0/24 is used in example)
iptables -A INPUT -m state --state NEW -s 10.20.30.0/24 -j ACCEPT

# Whitelist your IPs - repeat this step for each of your IPs permitted
# to access the machine outside of local network
iptables -A INPUT -s IPADDRESS -m state --state NEW -j ACCEPT

# If you have other services you want to configure for *public* access, then
# use this rule as a template and execute this before you follow the last step.
#
# Change PROTO to the protocol (tcp/udp, etc.) and PORT to the port number 
# (80 for HTTP, ex.)
#
# Add this to the end of the rule if you want to allow only certain 
# IPs to the specified service:
#   -s IPADDRESS 
iptables -A INPUT -p PROTO --dport PORT -m state --state NEW -j ACCEPT

# Deny all other traffic
iptables -A INPUT -j REJECT --reject-with icmp-host-unreachable