# What is a Transparent Proxy?

> A transparent proxy is an industry term for a proxy deployment in which network traffic is redirected to an intermediary without each client being explicitly configured to use it.

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- Language: en
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## Content

“Interception proxy” is more precise because the device still changes the communication path and may change protocol behavior. Transparent describes client configuration, not an absence of security, privacy, or compatibility effects.

Redirection may use routing, policy-based forwarding, firewall rules, or another middlebox. Plain HTTP can be processed after interception, but HTTPS remains unreadable unless the intermediary terminates TLS using trust installed on managed clients. Certificate pinning, mutual TLS, QUIC, non-web protocols, IPv6, and alternate routes can prevent inspection.

### Key points

- **Steering and scope:** Document which networks, users, protocols, ports, and address families are intercepted. Exemptions should be narrow, approved, monitored, and tested for unintended bypass.
- **Attribution:** Preserve source identity safely and define which systems may trust proxy-added headers. Network address translation or shared devices can otherwise make logs misleading.
- **Privacy and consent:** TLS interception can expose highly sensitive content. Use a lawful, documented purpose, minimize collection and retention, protect trust keys, and exclude traffic that should not be decrypted.
- **Important limitation:** Interception cannot be assumed invisible or universal. It may break applications, weaken end-to-end authentication, miss alternate paths, and become a bottleneck or single point of failure. An unaware client also cannot make proxy-specific error or trust decisions.

### Related terms

[Proxy server](<https://yellowcube.eu/glossary/proxy-server/>) · [Secure web gateway (SWG)](<https://yellowcube.eu/glossary/secure-web-gateway/>) · [Network address translation (NAT)](<https://yellowcube.eu/glossary/network-address-translation/>) · [Network traffic](<https://yellowcube.eu/glossary/network-traffic/>) · [Encryption](<https://yellowcube.eu/glossary/encryption/>)

### Sources

[RFC 3040: Internet Web Replication and Caching Taxonomy](https://www.rfc-editor.org/rfc/rfc3040) · [RFC 3234: Middleboxes](https://www.rfc-editor.org/rfc/rfc3234) · [RFC 9110: HTTP Semantics](https://www.rfc-editor.org/rfc/rfc9110)

## Attribution and scope

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