Avaya B5800 Bedienungsanleitung PDF herunterladen (Seite 278)

packet, up through the application layer, is examined. A stateful inspection firewall also

monitors the state of the connection and compiles the information in a state table. Stateful

inspection firewalls close off ports until the connection to the specific port is requested. This is

an enhancement to security against port scanning. Port scanning is the act of systematically

scanning a computer's ports. Since a port is a place where information goes into and out of a

computer, port scanning identifies open doors to a computer. Port scanning has legitimate uses

in managing networks, but port scanning also can be malicious in nature if someone is looking

for a weakened access point to break into your computer.

Firewall policies

The goals of firewall policies are to monitor, authorize and log data flows and events. They

also restrict access using IP addresses, port numbers and application types and sub-types.

This appendix focuses on identifying the port numbers used by Avaya products so effective

firewall policies can be created without disrupting business communications or opening

unnecessary access into the network.

Knowing that the source column in the port usage tables provided below is the socket initiator

is key in building some types of firewall policies. Some firewalls can be configured to

automatically create a return path through the firewall if the initiating source is allowed through.

This option removes the need to enter two firewall rules, one for each stream direction, but

can also raise security concerns.

Another feature of some firewalls is to create an umbrella policy that allows access for many

independent data flows using a common higher layer attribute. Finally, many firewall policies

can be avoided by placing endpoints and the servers that serve those endpoints in the same

firewall zone.

TFTP port usage

IP Office upgrade wizard and VM Pro all use TFTP for commands and data transfer. B5800

Branch Gateway implements a version of the TFTP Transfer Identifier mechanism (TID)

defined by RFC 1350.

The general mechanism is each has a TFTP listener on port 69, any received command (READ

request) is responded to with a TFTP response (WRITE request) to port 69. Any subsequent

data transfer uses the source ports from both request and response.

IP Office Manager (upgrade wizard) B5800 Branch Gateway

TFTP Read, src port 2421, dst port 69 >

< TFTP Write, src port 4153, dst port 69

Avaya port matrix for B5800 Branch Gateway and SIP phones

278 Implementing the Avaya B5800 Branch Gateway for an Avaya Aura

Configuration October 2012

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Avaya B5800 Bedienungsanleitung Seite 278