Network Security & Firewalls

A firewall is a piece of hardware and/or software which functions in a networked environment to prevent some communications forbidden by the security policy.  They are analogous to the function of firewalls in building construction. A firewall has the basic task of controlling traffic between different zones of trust. Typical zones of trust include the Internet (a zone with no trust) and an internal network (a zone with high trust). The ultimate goal is to provide controlled connectivity between zones of differing trust levels through the enforcement of a security policy and connectivity model based on the least privilege principle.

There are three basic types of firewalls depending on whether the communication is being done between a single node and the network, or between two or more networks whether the communication is intercepted at the network layer, or at the application layer; whether the communication state is being tracked at the firewall or not

With regard to the scope of filtered communication there exist:

personal firewalls, a software application which normally filters traffic entering or leaving a single computer through the Internet
network firewalls, normally running on a dedicated network device or computer positioned on the boundary of two or more networks or DMZs (demilitarized zones). Such a firewall filters all traffic entering or leaving the connected networks.
The latter definition corresponds to the conventional, traditional meaning of "firewall" in networking.

In reference to the layers where the traffic can be intercepted, three main categories of firewalls exist:

network layer firewalls
application layer firewalls
application firewalls

These network-layer and application-layer types of firewall may overlap, even though the personal firewall does not serve a network; indeed, single systems have implemented both together.

There's also the notion of application firewalls which are sometimes used during wide area network (WAN) networking on the world-wide web and govern the system software. An extended description would place them lower than application layer firewalls, indeed at the Operating System layer, and could alternately be called operating system firewalls.

Lastly, depending on whether the firewalls track packet states, two additional categories of firewalls exist: stateful firewalls and stateless firewalls. 
A stateful firewall (any firewall that performs stateful packet inspection or stateful inspection) is a firewall that keeps track of the state of network connections (such as TCP streams) traveling across it. The firewall is programmed to know what legitimate packets are for different types of connections. Only packets which match a known connection state will be allowed by the firewall; others will be rejected.

Proper configuration of firewalls demands skill from the administrator. It requires considerable understanding of network protocols and of computer security. Small mistakes can render a firewall worthless as a security tool.

Data Connect Enterprise offers a full range of Network Security & Firewall Products
From Cisco, SonicWall, NetGear, Zyxel and others

Please contact us 301-924-7400

ADTRAN Products with Firewalls
Adtran 2050 1202362L2
Adtran Internet Security Firewall Appliances
Adtran 1224 1200500L1 24 Port Managed Switch
Adtran 2100 1200361L2
Adtran 2050 1200362L1
Adtran 1224ST 1200504L1
Adtran 2300 1200366L1
Adtran 2400 1200367L1
Adtran 2300 NetVanta VPN 4200366L1#10
Adtran 2400 NetVanta VPN 100 users 4200367L1#100
Adtran 3200 T1 / FT1 4200862L1
Adtran Routers
Adtran NetVanta 2000 NetVanta 2050, NetVanta 2100, NetVanta 2300 ,NetVanta 2400, NetVanta VPN Client
Adtran 3205 Chassis 1200870L1
Adtran 3200 Chassis 1200860L1
Adtran 3200 Serial 4200866L1
Adtran 3205 DC Chassis 1200980L1
Adtran 3305 1200880L1
Adtran 3205 Chassis VPN 4200870L2
Adtran 3200 T1 / FT1 VPN Bundle 4200862L2
Adtran 3205 56k/64k 4200871L1
Adtran 3200 T1 / FT1 DSX-1 VPN 4200863L2
Adtran 3200 Chassis VPN Bundle 4200860L2
Adtran 3205 T1 FT1 + DSX-1 4200873L1
Adtran 3200 with 56k/64k NIM 4200861L1
Adtran 3305 T1 FT1 DSX-1 4200883L1
NetVanta 3200 T1 / FT1 DSX-1 4200863L1
Adtran 3200 56/64K NIM VPN 4200861L2
Adtran 3205 Serial 4200876L1
Adtran 3205 T1 FT1 DSX-1 VPN 4200873L2
Adtran 3305 T1 FT1 DSX-1 VPN 4200883L2
Adtran 3205 T1 FT1 4200872L1
Adtran 3305 T1 FT1 4200882L1
Adtran 3305 Chassis VPN 4200880L2
NetVanta 3205 56/64K VPN Bundle 4200871L2
Adtran 3205 T1 FT1 VPN 4200872L2
Adtran 3305 T1 FT1 VPN 4200882L2
Adtran 3305 Dual Slot Dual Ethernet Access Router


Patton Routers w/ Firewalls
Patton Electronics 2603/T/48 T1/E1 (RJ45) ROUTER W/ 48VDC
Patton Electronics 2621/EUI X.21 ROUTER
Patton Electronics SmartNode 2300 Modular VoIP Access Router
Patton Electronics 2635/48 V.35 ROUTER 48 VDC
Patton Electronics 2635/E V.35 ROUTER NO POWER SUPPLY
Patton Electronics 2621/E X.21 WAN ROUTER, No Power Supply
Patton Electronics 2621/48 X.21 ROUTER Ext 48VDC
Patton Electronics 2635/EUI V.35 ROUTER
Patton Electronics 2635/UI V.35 ROUTER
Patton Electronics 2621/UI X.21 ROUTER
Patton Electronics 2603/T/EUI T1 RJ45 ROUTER WITH EXT 120-220 VAC
Patton Electronics 2603/T/UI T1 RJ45 ROUTER WITH INTERNAL 120-220 VAC
Patton Electronics 2603/K/48 T1 E1 ROUTER 48VDC
Patton Electronics 2603/K/E E1 (RJ45/BNC) ROUTER NO POWER SUPPLYP
Patton Electronics 2603/T/E T1 BNC ROUTER NO POWER SUPPLY
Patton Electronics 2603/K/EUI E1 (RJ45/BNC) ROUTER EXT 120-220 VAC
Patton Electronics 2621 Router IP
Patton Electronics 2635 Router IP
SonicWall Firewall
SonicWall Switch Firewall
Symantec Firewall
Symantec Firewall Appliances


Data Connect Enterprise offers a full range of Network Security & Firewall Products

Contract Buying and Volume Discounts available !!

Please contact us 301-924-7400