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TLS Extensions 65037 during client hello since firefox 118 (Windows)

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  • Last reply by Lukasz

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Hello,

I see with windows Firefox version 118 a TLS extension id 65037 on every client hello handshake containing a bunch of data. Does somebody know what this extension is used for? I couldn't find anything about this on the web or in the firefox docs / release notes. Other browser (chrome / edge) don't have this extension in use.

Thanks

Hello, I see with windows Firefox version 118 a TLS extension id 65037 on every client hello handshake containing a bunch of data. Does somebody know what this extension is used for? I couldn't find anything about this on the web or in the firefox docs / release notes. Other browser (chrome / edge) don't have this extension in use. Thanks
Attached screenshots

Chosen solution

That is Encrypted Client Hello (ECH), it will go away if you change security.tls.ech.grease_probability to 0 in about:config. Chrome has it behind a flag.

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Chosen Solution

That is Encrypted Client Hello (ECH), it will go away if you change security.tls.ech.grease_probability to 0 in about:config. Chrome has it behind a flag.

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On Linux firefox 118 doesn't have this extension in use.

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It's a limited rollout, you can see them listed in about:support#remote-features.

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zeroknight said

That is Encrypted Client Hello (ECH), it will go away if you change security.tls.ech.grease_probability to 0 in about:config. Chrome has it behind a flag.

Thank you for clarification.

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