Installation guide

Packet filtering 30-14
Chapter 30: Understanding Wave Data Networking
Wave Global Administrator Guide
Protocol and port filtering of common services
The most specific type of filtering is known as protocol filtering or port filtering. This allows
only specific protocols on an interface. For example, you may wish to disallow FTP over your
connection to the Internet. These types of filters can be complex to set up and maintain.
Wave packet filters can only perform simple filters on the protocols, since they are not dynamic
nor do they track the state of the connection. A more sophisticated firewall or network proxy is
needed for complex environments and protocols.
A common practice is to limit access to the Internet to only a few different services and ports.
This is fairly straightforward if there are no Internet servers (such as web or email) located
on-site. To do this, you would set up a “dump all except listed below” filter which allows only
specific protocols and ports.
Typically, this list includes the TCP and UDP services listed in the following table. This is a
subset of what is referred to as
well-known port numbers, which is documented in various
places, such as STD 0002 (also known as RFC 1700). While most services’ ports are valid for
both TCP and UDP, in practice you will probably only see one or the other.
Input/Output Destination 10.0.0.0 255.0.0.0
Input/Output Destination 172.16.0.0 255.240.0.0
Input/Output Destination 192.168.0.0 255.255.0.0
Common ports for TCP and UDP
Service Port Full Name
DNS 53 Domain Name Services
FTP 20, 21 File Transfer Protocol
Gopher 70 Gopher
HTTP 80 World Wide Web HyperText Transfer Protocol
IMAP4 143 Interim Mail Access Protocol, Version 4
Outbound and inbound filters
Direction Filter Type IP Network Address Subnet Mask
Release 2.0
September 2010