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Diffstat (limited to 'tracker/Publish_an_SPF_policy_to_the_DNS_zone.mdwn')
| -rw-r--r-- | tracker/Publish_an_SPF_policy_to_the_DNS_zone.mdwn | 57 |
1 files changed, 0 insertions, 57 deletions
diff --git a/tracker/Publish_an_SPF_policy_to_the_DNS_zone.mdwn b/tracker/Publish_an_SPF_policy_to_the_DNS_zone.mdwn deleted file mode 100644 index bdbec77..0000000 --- a/tracker/Publish_an_SPF_policy_to_the_DNS_zone.mdwn +++ /dev/null @@ -1,57 +0,0 @@ -We need to create a new subdomain `outgoing.fripost.org` which A and -AAAA records point to machines currently serving as outgoing SMTP -servers. Then we would add the following records to the DNS zone -([RFC 4408 section 3.1.1](https://tools.ietf.org/html/rfc4408#section-3.1.1) -recommends both SPF and TXT records, with identical content.): - - outgoing.fripost.org IN SPF "v=spf1 a ~all" - outgoing.fripost.org IN TXT "v=spf1 a ~all" - fripost.org IN SPF "v=spf1 redirect=outgoing.fripost.org" - fripost.org IN TXT "v=spf1 redirect=outgoing.fripost.org" - -That essentially means whenever someone receives a message from a -`@fripost.org` address, we can say the address hasn't been spoofed (or -been spoofed by another fripost member) if the message was originating -from `outgoing.fripost.org` (i.e., was sent from the webmail, the Mail -Submission Agent, or was the target of an alias or subscribed on a -list). Otherwise, things are like there wasn't an SPF policy. With that -information at hand, the recipient may decide to classify the message as -SPAM or HAM for instance. - -If we were to disallow (we probably aren't) messages from `@fripost.org` -addresses to be sent from anything else than what `outgoing.fripost.org` -points to, we could replace the trailing `~all` (softfail) by `-all` -(fail). - -Having an SPF policy for Fripost is also useful for domains using -fripost.org as MX:es. For instance, to allow `@example.org` messages to -be sent from either `fripost.org`'s outgoing machines (without knowing -what they are a priori, therefore the SPF policy is copied) or -`example.org`'s A/AAAA records, but nothing else: - - example.org IN SPF "v=spf1 ?include:fripost.org a -all" - example.org IN TXT "v=spf1 ?include:fripost.org a -all" - -Hopefully one day we'll have DNSSEC, defeating DNS-spoofing. The the -[qualifier](https://tools.ietf.org/html/rfc4408#section-5.2) could be -changed to something tighter: - - example.org IN SPF "v=spf1 include:fripost.org a -all" - example.org IN TXT "v=spf1 include:fripost.org a -all" - -Here too the default action `-all` (fail) could be replaced by `~all` -(softfail) to allow mails from `@example.org` addresses to be sent from -other locations, but without asserting they aren't spoofed in that case. - -If `example.org`'s has no A/AAAA records, or if the machine they point -to are not supposed to relay mails to the outside, one may prefer to -merely copy our policy: - - example.org IN SPF "v=spf1 redirect=outgoing.fripost.org" - example.org IN TXT "v=spf1 redirect=outgoing.fripost.org" - -References: RFCs [4408](https://tools.ietf.org/html/rfc4408) and -[6652](https://tools.ietf.org/html/rfc6652); See also the -[Wikipedia page](https://en.wikipedia.org/wiki/Sender_Policy_Framework). - -[[closed]] |