ZyWALL 2 Series User’s Guide
10.5.5 Upper Layer Protocols
Some higher layer protocols (such as FTP and RealAudio) utilize multiple network connections simultaneously. In general terms, they usually have a "control connection" which is used for sending commands between endpoints, and then "data connections" which are used for transmitting bulk information.
Consider the FTP protocol. A user on the LAN opens a control connection to a server on the Internet and requests a file. At this point, the remote server will open a data connection from the Internet. For FTP to work properly, this connection must be allowed to pass through even though a connection from the Internet would normally be rejected.
In order to achieve this, the ZyWALL inspects the
Any protocol that operates in this way must be supported on a
10.6 Guidelines For Enhancing Security With Your Firewall
1.Change the default password via SMT or web configurator.
2.Think about access control before you connect a console port to the network in any way, including attaching a modem to the port. Be aware that a break on the console port might give unauthorized individuals total control of the firewall, even with access control configured.
3.Limit who can telnet into your router.
4.Don't enable any local service (such as SNMP or NTP) that you don't use. Any enabled service could present a potential security risk. A determined hacker might be able to find creative ways to misuse the enabled services to access the firewall or the network.
5.For local services that are enabled, protect against misuse. Protect by configuring the services to communicate only with specific peers, and protect by configuring rules to block packets for the services at specific interfaces.
6.Protect against IP spoofing by making sure the firewall is active.
7.Keep the firewall in a secured (locked) room.
10.7 Packet Filtering Vs Firewall
Below are some comparisons between the ZyWALL’s filtering and firewall functions.
Firewalls |