gistfile1.txt

# Remove all rules and chains
iptables -F
iptables -X

# first set the default behaviour => accept connections
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT

# Create 2 chains, it allows to write a clean script
iptables -N FIREWALL
iptables -N TRUSTED

# Allow ESTABLISHED and RELATED incoming connection
iptables -A FIREWALL -i eth0 -m state --state ESTABLISHED,RELATED -j ACCEPT
# Allow loopback traffic
iptables -A FIREWALL -i lo -j ACCEPT
# Send all package to the TRUSTED chain
iptables -A FIREWALL -j TRUSTED
# DROP all other packets
iptables -A FIREWALL -j DROP

# Send all INPUT packets to the FIREWALL chain
iptables -A INPUT -j FIREWALL

# DROP all forward packets, we don't share internet connection in this example
iptables -A FORWARD -j DROP

iptables -A TRUSTED -i eth0 -p tcp -m tcp --dport 22 -j ACCEPT
iptables -A TRUSTED -i eth0 -p tcp -m tcp --dport 80 -j ACCEPT

gistfile2.txt

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
  12M 1058M FIREWALL   all  --  *      *       0.0.0.0/0            0.0.0.0/0           

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0           

Chain OUTPUT (policy ACCEPT 7722K packets, 27G bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FIREWALL (1 references)
 pkts bytes target     prot opt in     out     source               destination         
  11M 1017M ACCEPT     all  --  eth0   *       0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED 
 330K   30M ACCEPT     all  --  lo     *       0.0.0.0/0            0.0.0.0/0           
 199K   11M TRUSTED    all  --  *      *       0.0.0.0/0            0.0.0.0/0           
 5373  243K DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0           

Chain TRUSTED (1 references)
 pkts bytes target     prot opt in     out     source               destination         
  176 10536 ACCEPT     tcp  --  eth0   *       0.0.0.0/0            0.0.0.0/0           tcp dpt:22 
 194K   11M ACCEPT     tcp  --  eth0   *       0.0.0.0/0            0.0.0.0/0           tcp dpt:80