Opsætning af DMARC

DMARC skal sikre os at vi tjekker for SPF og DKIM “digital signatur” inden vi modtager en mail på vores server i office 365.

Inde du går i gang skal du tjekke at du har adgang til kundens DNS records

Start med at oprette en e-mail shared mailbox til at opsamle fejl rapporter. F.eks. dmarc@domænenavn.dk

Til at generere vores TXT DNS record benytter vi denne side Link eller benyt mxtoolbox.

Der skal laves en txt record:

 _DMARC.domænenavn.dk

Value:

v=DMARC1; p=none; rua=mailto:dmarc@domænenavn.dk; ruf=mailto:dmarc@domænenavn.dk; fo=1
v=DMARC1;p=none;sp=reject;pct=100;rua=mailto:dmarc@uni-it.dk;ruf=mailto:dmarc@uni-it.dk;ri=86400;aspf=r;adkim=r;fo=1

Link til artikel hos CloudFactory:

Test din record hos mx toolbox.

Her er forklaring på en enkelte records

v (required)The version tag. The only allowed value is “DMARC1”. If it’s incorrect or the tag is missing, the DMARC record will be ignored.
p (required)The DMARC policy. Allowed values are “none”, “quarantine”, or “reject“. The default is “none,” which takes no action against non-authenticated emails. It only helps collect DMARC reports and gain insight into your current email flows and their authentication status. “quarantine” marks the failed emails as suspicious, while “reject” blocks them.
ruaAggregate report sending destination. It’s the “mailto:” URI that ESPs use to send failure reports. The tag is optional, but you won’t receive reports if you skip it.
rufForensic (Failure) report sending destination. It’s the “mailto:” URI that ESPs use to send failure reports. The tag is optional, but you won’t receive reports if you skip it.
spThe subdomain policy. The subdomain inherits the domain policy tag (p=) explained above unless specifically defined here. Like the domain policy, the allowed values are “none,” “quarantine,” or “reject.” This option isn’t widely used nowadays.
adkimThe DKIM signature alignment. This tag follows the alignment between the DKIM domain and the parent Header From domain. Allowed values are “r” (relaxed) or “s” (strict). “r” is the default and allows a partial match, while the “s” tag requires the domains to be the same.
aspfThe SPF alignment. This tag follows the alignment between the SPF domain (the sender) and the Header From domain. Allowed values are “r” (relaxed) or “s” (strict). “r” is the default, and allows a partial match, while the “s” tag requires the domains to be exactly the same.
foForensic reporting options. Allowed values are “0,” “1,” “d,” and “s.” “0” is the default value, which generates a forensic report when both SPF and DKIM fail to produce an aligned pass. If either of the protocol outcomes is something other than pass, use “1.” “d” generates a report when DKIM is invalid, while “s” does the same for SPF. Define the ruf tag to receive forensic reports.
rfThe reporting format for failure reports. Allowed values are “afrf” and “iodef”.
pctThe percentage tag. This tag works on domains with a “quarantine” or “reject” policy only. It marks the percentage of failed emails a given policy should be applied to. The rest falls under a lower policy. For example, if “pct=70,” on a domain with a “quarantine” policy, it applies only 70% of the time. The remaining 30% goes under “p=none”. Similarly, if “p=reject” and “pct=70,” “reject” applies to 70% of failed emails, and 30% go into “quarantine.”
riReporting interval. Marks the frequency of received XML reports in seconds. The default is 86400 (once a day). Regardless of the set interval, in most cases, ISPs send the reports at different intervals (usually once a day).
  • Opsætning af DMARC

  • Opsætning af DKIM

  • Certificate on esxi 6.7 / 7.0

  • Test din adblocker

  • Tjeck at et domæne understøtter TLS kryptering

  • Synology VPN Plus Client Not Installed

Opsætning af DKIM

Forberedelse: Tjek at du har adgang kundens DNS records

Trin til oprettelse af DKIM

1.Log ind på siden https://security.microsoft.com/dkimv2

Klik på det domæne du vil oprette DKIM for

2. Klik på opret DKIM -nøgler

Der genereres nu domænenøgler Der oprettes 2 stk CNAME. Host Name : selector1._domainkey
Points to address or value: selector1-domæne-dk._domainkey.arkitektsk.onmicrosoft.com

Host Name : selector2._domainkey
Points to address or value: selector2-arkitektsk-dk._domainkey.arkitektsk.onmicrosoft.com

Tryk nu enable DKIM

Verifices DKIM hos microsoft

https://admin.microsoft.com/AdminPortal/?searchSolutions=DKIM#/homepage

Kør nu en test og tjeck at det er sat rigtigt op.

Dobbelt tjeck hos mx toolbox. selector er = selector1

Link:

Her er resultatet

  • Opsætning af DMARC

  • Opsætning af DKIM

  • Certificate on esxi 6.7 / 7.0