From bd608f118b0553d5450f8575093ba62a1fcecbe5 Mon Sep 17 00:00:00 2001 From: Dennis Baaten Date: Thu, 6 Jun 2019 16:45:15 +0200 Subject: [PATCH] Updated DKIM how to (markdown) --- DKIM-how-to.md | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/DKIM-how-to.md b/DKIM-how-to.md index 2c8a37f..e00bfa4 100644 --- a/DKIM-how-to.md +++ b/DKIM-how-to.md @@ -2,14 +2,15 @@ This how to is created by the Dutch Internet Standards Platform (the organization behind [internet.nl](https://internet.nl)) and is meant to provide practical information and guidance on implementing DKIM. # What is DKIM? -DKIM stands for **D**omain**K**eys **I**dentified **M**ail and is described in RFC 6376](https://tools.ietf.org/html/rfc6376) with updates in [RFC 8301](https://tools.ietf.org/html/rfc8301) and {RFC 8463](https://tools.ietf.org/html/rfc8463). It is meant to provide the owner of a domain with the means to claim that a message has actually been send by the domain's e-mail server and should therefore be considered legitimate. It works by signing every individual e-mail message with a specific key (private key), so that the receiving party can use a corresponding key (public key) published in the sending domain's DNS record to validate the e-mail authenticity and to check whether the e-mail has not been tampered with. +DKIM stands for **D**omain**K**eys **I**dentified **M**ail and is described in [RFC 6376](https://tools.ietf.org/html/rfc6376) with updates in [RFC 8301](https://tools.ietf.org/html/rfc8301) and [RFC 8463](https://tools.ietf.org/html/rfc8463). It is meant to provide the owner of a domain with the means to claim that a message has actually been send by the domain's e-mail server and should therefore be considered legitimate. It works by signing every individual e-mail message with a specific key (private key), so that the receiving party can use a corresponding key (public key) published in the sending domain's DNS record to validate the e-mail authenticity and to check whether the e-mail has not been tampered with. # Why use DKIM? A common used technique used by spammers is to trick the receiving party into believing an e-mail is legitimate by using a forged sender address. This is also known as e-mail spoofing. DKIM has been designed to protect against spoofing. If an incoming e-mail does not have a DKIM signature or when it's DKIM signature does not validate, the receiving e-mail server should consider the e-mail to be SPAM. # Tips, tricks and notices for implementation -* parked domain -* minimum key length +* Use a DKIM key (RSA) of [at least 1024 bits](https://tools.ietf.org/html/rfc6376#section-3.3.3) to minimize the successrate of offline attacks. Don't go beyond a key size of 2048 bits since this is not mandatory according to the RFC. +* Make you to change your DKIM keys regularly. A rotation scheme of 6 months is recommended. +* Parked domains should be explicitly configured to not use e-mail. For DKIM this is done with an empty policy: "v=DKIM1; p=". # Outbound e-mail traffic DNS record