Different firewall configuration:

• ScreenHost firewall/Single home bastion
• ScreenHost firewall dual home bastion
• Screened Subnet firewall

1] ScreenHost firewall:-

• In this configuration, there are two firewalls; Application gateway & packet filter which are between the internal network
• Each & every host of the internal network is connected to application gateway & filter firewall.
• The packet filter performs filtering on each & every packet performs the proxy functions.
• The main disadvantage of this approach is if the attacker somehow attacks the packet filter firewall then he can access the internal system.

2] Screened Host Firewall Dual Home Bastion:-

• In this configuration there is no end to end connection between the internal host and the packet filter firewall.
• It is used to address the drawback of previous approch.
• The internal host is connected to the application gateway,the application gateway is further connected to packet filter and the packet filter is connected to internet.
• In this schema if the attacker tries to break the packet filter firewall then he/she has still to break the application gateway to enter into the internal network.

3] Screened Subnet firewall:-

• This is the most secure firewall configuration in which there are three firewalls between the internal and the internet
• If the attacker wants to enter into the private network then he has to break into all the three firewalls.