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XG 18.0.4 M4-4 Mac Mail IMAP unable to connect (DPI issue)

Hi There,

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 ?

  • Is there any way I can view the DPI engine log verbosely to see if that shows anything ?
  • I've tried a tcpdump for port 993 on the firewall but that wasn't too helpful
  • The Mac apps don't place nicely with HTTPS/SSL proxy apps so that doesn't help much.

Thanks



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Parents
  • Eventually the SSL/TLS inspection log showed "Dropped due to TLS engine error: FLOW_TIMEOUT[5]" 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.

    • Created FQDN host "*.yahoo.com"
    • Created new Firewall rule (see below for config)
    • SSL/TLS inspection has to remain turned off, turning it back on creates the same problem again.

    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.

  • Hi,

    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 have to add the sites to be excluded from scanning?

    Ian

     
    V18.5.x - e3-1225v5 6gb ram with 4 ports - 20w. 
    3 AP55s and 2 APX120s having a holiday until software update is released.
    If a post solves your question use the 'This helped me' link.
  • 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. 

    __________________________________________________________________________________________________________________

  • , 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 

    • SSL/TLS inspection on
    • DPI exception rule created as in picture above (I've also tried adding yahoo.com & imap.mail.yahoo.com to the "Local TLS exclusion list" URL group which is already included in the DPI exception rule "Exclusions by website or category" and is set to "Don't decrypt"
    • Firewall rule created as in my original post picture

    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 ?

  • Hi,

    I created anew yahoo account because I can't remember the password or setup on my old one.

    Testing, I saw the following ports 143, 443, 585 and 993 all trying to talk to the  mail server imap.mail.yahoo.com. All validation attempts failed with or without using the HTTP proxy. No errors logged in the XG.

    Result, total failure.

    Ian

     
    V18.5.x - e3-1225v5 6gb ram with 4 ports - 20w. 
    3 AP55s and 2 APX120s having a holiday until software update is released.
    If a post solves your question use the 'This helped me' link.
  • __________________________________________________________________________________________________________________

  • Thanks for taking the time to test that out rfcat_vk, appreciate it.

  • Working as expected now with MR5, thanks LuCar Toni.Thumbsup

    • No exclusions needed.
    • No firewall rules needed.
    • SSL/TLS inspection on or off, works fine.
  • interesting, my mac mail will not connect with or without XG involved, verification fails for Yahoo mail.

    According to Sophos there are NO fixes for DPI in MR-5, testing was not completed in time to be added.

    Ian

     
    V18.5.x - e3-1225v5 6gb ram with 4 ports - 20w. 
    3 AP55s and 2 APX120s having a holiday until software update is released.
    If a post solves your question use the 'This helped me' link.
  • EDIT: Sorry just saw you said with or without XG involved, different issue entirely ?

    I think I read in some of your other posts that you have mail scanning options enabled to make Mac's Mail app work ?, do you want to scan mail ports ?, could you try turning off any mail scanning enabled ?

    So with my setup now on 18.0.5 MR-5:

    • Default network rule does not have any mail scanning enabled (Scan IMAPS and Scan SMTPS not ticked), firewall is NOT in MTA mode.
    • SSL/TLS inspection on
    • Web > URL groups > "Local TLS exclusion list" is empty.
    • No firewall rule for Yahoo or any mail port handling.

    Default network rule Security & Other settings:

    Mac Mail Connection Doctor app:

  • Hi,

    I scan mail in an attempt to catch virus and spam. Scanning works for all mail accounts on mac mini, mac air, iPad and iPhones.

    Yahoo smtp worked with scanning when the CA was told to trust the site, though the Yahoo CA is invalid.

    I am at  loss to understand why Yahoo Spam fails to verify? I will ask in other forums though the answer is not of great interest because I do not use Yahoo mail on a regular basis.

    Ian

     
    V18.5.x - e3-1225v5 6gb ram with 4 ports - 20w. 
    3 AP55s and 2 APX120s having a holiday until software update is released.
    If a post solves your question use the 'This helped me' link.
  • Ah no worries, don't worry about finding a fix as my problem has now been resolved, can leave it there.

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