I'm not sure when it started but on a Mac if I'm using the Mail app or the Outlook app and try to add a Yahoo IMAP account the XG Firewall is not allowing it to connect using SSL 993 and I can't see why, it is the DPI engine that is responsible for this as if I go to "Rules and Policies" > "SSL/TLS inspection rules" > "SSL/TLS inspection settings" > "Advanced settings" and turn off "SSL/TLS engine" everything starts working fine, I cannot see any logs in the Log Viewer to suggest dropped packet data for any reason. I'm not using any mail scanning settings or anything complicated/specific, can anyone advise ?
the DPI engine does not work with mail ports, 465, 993, 587, 25. You need to use the mail proxy. MAC mail does work with CAs and mail proxy scanning.
What is the use of using the DPI engine if you…
Eventually the SSL/TLS inspection log showed "Dropped due to TLS engine error: FLOW_TIMEOUT" errors, I suspect this was after enabling "SSL/TLS inspection" which enabled logging ?, searching the forums for that showed a history of problems related to this and the DPI engine, after following some fixes recommended from some posts I've created a temporary solution. Also looking at Mail's Connection Doctor it shows a connection to imap.mail.yahoo.com over port 143 which is non-secure IMAP, turning off SSL/TLS inspection (NOT the SSL/TLS engine) and creating the Firewall rule below allows it to connect over 993, I did add the Sophos SSL and CA certs into the Keychain but it made no difference, IMAP connections to iCloud and GMAIL seem to work fine, just Yahoo that doesn't.
There is a setting which allows you to exclude domains from SSL/TLS inspection however it seems the Firewall ignores this ?, The "Exclusions by website or category" has the "Local TLS exclusion list" URL list in it, so I added "yahoo.com" to the "Local TLS exclusion list" URL list but this made no difference.
What is the use of using the DPI engine if you have to add the sites to be excluded from scanning?
Thanks for the response rfcat_vk, interesting to know the DPI engine does not work with mail ports, is there documentation that supports or mentions this ?
I've read your other posts about adding the CA into Keychain which I did try but did not work, I assume this is because I did not setup mail proxy, I assume by mail proxy you mean switching to MTA mode ?, it doesn't really answer why Mac Mail works with GMAIL/iCloud IMAP 993 connections and not Yahoo.
no, I meant via enabling the scanning within your firewall rule. I have one mac air running both outlook and Mac mail with 3 accounts and 4 other devices all running mac mail (3 of them are mobile devices all apple based). Mail fails on all devices when using DPI, but works when using scanning within the firewall rules. I have the XG CA installed on all devices.
Possibly there are default exceptions in the SSL/TLS settings.
As far as documentation on mail and the DPI, the issue was confirmed in a long running thread on DPI issues as not being fixed in the upcoming MR-x with the DPI fix-
So based on what you you said I made the following changes yesterday but was not successful in getting Yahoo to work, it is worth noting that it is specifically Yahoo IMAP 993 that is failing to connect (imap.mail.yahoo.com)
I did try other settings like unticking "Use web proxy instead of DPI engine", ticking "Decrypt HTTPS during web proxy filtering", ticking "Scan HTTP and decrypted HTTPS" but was unsuccessful, if I disable the new firewall rule I've created and enable SSL/TLS inspection everything works except Yahoo IMAP, the GMAIL and iCloud IMAP 993 connections go through fine without any certs installed on devices or any exceptions or any firewall rule changes.
What do you mean you turned on SSL/TLS inspection?
See below picture for SSL/TLS inspection enable/disable setting:
If I keep it turned off and enable the firewall rule in the picture in my first post, Yahoo IMAP 993 using macOS's Mail app works, HOWEVER, if I turn that setting on, it causes problems again even with firewall rule enabled.
Sophos support advise you should only change that setting under their guidance.
If *.yahoo.com fails with your firewall rule setup as per the top post with SSL/TLS enabled but not used in the rule then that would imply there is an issue with the Yahoo connection.
You might need to change the yahoo.com to *.mail.yahoo,com
Other than that I am running out of ideas.
Try to create a DPI rule with your IMAP Port 993 and do not decrypt.
It could be still a bug, which can be fixed with MR5, as there was a bug about false categorization, if i remember correctly.
rfcat_vk, yeah I'm a bit lost as to what it could be, I did try changing *.yahoo.com to *.mail.yahoo.com but no difference.
@LuCar Toni, Thanks for the suggestion, I did try this before as that is exactly what I would expect to work but it did not, see below for the rule I tried to create and select "Don't decrypt".
If I have
Still does not work, whenever I turn on SSL/TLS inspection it just breaks it.
Is there any news about when MR5 will be released ?