When a firewall acts as an application-level gateway (ALG), what does it require in order to establish a connection?

The correct answer is A. Pinhole. An Application-Level Gateway (ALG) is aware of application-layer protocols (e.g., FTP, SIP, H.323) that dynamically negotiate secondary connections. To allow these secondary connections, the firewall creates a 'pinhole' - a temporary, dynamic opening in the security policy that…

Understand Advanced Firewall Features and Application-Level Gateway (ALG) Operations

Question

Options

APinhole
BDynamic IP and Port (DIPP)
CSession Initiation Protocol (SIP)
DPayload

How the community answered

(33 responses)

A
94% (31)
B
3% (1)
C
3% (1)

Explanation

An Application-Level Gateway (ALG) is aware of application-layer protocols (e.g., FTP, SIP, H.323) that dynamically negotiate secondary connections. To allow these secondary connections, the firewall creates a 'pinhole' - a temporary, dynamic opening in the security policy that permits the negotiated traffic. The ALG inspects the control-plane payload to learn what ports/IPs to expect, then punches the pinhole to allow that secondary data-plane session. SIP (C) is an example of a protocol that uses ALGs, not a requirement of ALGs in general. DIPP (B) relates to NAT, and payload (D) is what the ALG reads, not what it requires to open a connection.

Topics

#Firewall ALGs#Network Security#Port Management#Application Protocols

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