Description of Email Security testing tool in the diagnostics page

03/26/2020 1011 11172

DESCRIPTION:

Email Security firmware 8.x and above, has the ability to run queries for several DNS records, ping , and SMTP tests. In this article we will be explaining those options in details and provide some test examples showing how a correct reply to our query should look like.

RESOLUTION:

The Diagnostics page is visible under Investigate |Tools | Diagnostics

1. Run SMTP Test for specified Host or IP

This command is to verify if port 25 is open.It does not allow sending an email.
If the intention is to send an email, a manually telnet session to port 25 should be initiated.

Output for an open port 25 :

Output for a closed port 25:

2. Query DNS for A record of the specified Host:

This command performs a normal A record query to the DNS server configured under Manage | System Setup | Server | Host Configuration |Primary DNS server IP address and/or Fallback DNS server IP address

An example output of this test is as follows:

3. Query DNS for MX Record of the specified Host

This command performs a normal MX record query to the DNS server configured under Manage | System Setup | Server | Host Configuration |Primary DNS server IP address and/or Fallback DNS server IP address 

An example output of this test is as follows:

4. Query DNS for SPF Policy of the specified Host

The line starting with v=spf1 is an SPF record
Below are examples of a domain that does not have a SPF records (soniclab.com) and a domain that does have a SPF record (sonicwall.com)

5. Query DNS for DMARC Policy of the specified Host

DMARC policies are published in the DNS as text (TXT) resource records (RR) and announce what an email receiver should do with non-aligned mail it receives.

Consider an example DMARC TXT RR for the domain "sender.dmarcdomain.com" that reads:

EXAMPLE: v=DMARC1;p=reject;pct=100;rua=mailto:postmaster@dmarcdomain.com

In this example, the sender requests that the receiver by default reject all non-aligned messages. A report is sent, in a specified aggregate format, about the rejections to the sender. If the sender was testing its configuration, it could replace "reject" with "quarantine" which would tell the receiver they shouldn't necessarily reject the message, but consider quarantining it.

DMARC records follow the extensible "tag-value" syntax for DNS-based key records defined in DKIM.

The following chart illustrates some of the available tags:

 6. Query DNS for DKIM Policy of the specified Host 

DKIM, is the result of merging Domain Keys and Identified Internet Mail. This merged specification has been the basis for a series of IETF standards-track specifications and support documents which eventually resulted in STD 76.

DKIM records are in the following format:
[selector]._domainkey.[domain]

The selector and the domain are provided in the email headers of an email.
Emails signed with DKIM have a DKIM header from which format can be created

EXAMPLE:

DKIM-Signature: v=1; a=rsa-sha256; d=examplesonicwall.com; s=dkim1; c=relaxed/simple; q=dns/txt; l=1234; t=1117574938; x=1118006938; h=from:to:subject:date:keywords:keywords; bh=MTIzNDU2NzdfhsthjwyjDEyMzQ1Njc4OTAxMjM0NTY3ODkwMTI=; b=dzdVyOfAKCdLXdJOgjsrjwryc9G2q8LoXSlEniSbav+yuU4zGeeruD00lszZVoG4ZHRNiYzR

The correct DKIM format to query would look like the following:
dkim1._domainkey.examplesonicwall.com

7. Ping the specified Host of IP

This performs a normal ICMP ping

8. Connect to the specified Host 

This command performs and checks if TCP handshake is possible with a specified host based on a telnet over port 25.
If a domain is used, a DNS A record query would first take place .

NOTE: If the navigation or the screenshot looks different from the one mentioned above , you may be in an older firmware version and would require a firmware upgrade. Please refer the link below to upgrade the firmware to latest version.

https://www.sonicwall.com/en-us/support/knowledge-base/170504270079039