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Sistro Networks
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TLS Inspection Turns Your Firewall Into a PKI Problem

You enable TLS inspection.

Immediately a few applications stop working.

Why?

Because the firewall isn't simply reading encrypted packets.

It becomes part of the TLS trust path.

A simplified flow:

Client
→ Security Gateway
→ Decrypt
→ Security Inspection
→ Re-encrypt
→ Server

The client now needs to trust the certificate authority used by the gateway.

That creates several engineering problems:

CA distribution
endpoint management
certificate pinning
application compatibility
bypass policy
performance
privacy

Managed corporate laptops are relatively straightforward.

Unmanaged BYOD isn't.

A useful deployment strategy is:

Deploy the inspection CA
Select a small pilot group
Enable inspection
Identify application failures
Create narrow exclusions
Measure gateway load
Expand gradually

SonicWall DPI-SSL is a useful real-world example because it supports inspection policies and granular exclusions.

The lesson applies beyond SonicWall:

TLS inspection is part firewall, part PKI, part endpoint management.

Practical example:

https://sistro.net/sonicwall-dpi-ssl-inspeccion-https

Tags: cybersecurity tls networking security

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