krypted.com

Tiny Deathstars of Foulness

Mail is one of the hardest services to manage. Actually, mail is pretty simple in and of itself: there’s protocols people use to access their mail (such as IMAP and POP), protocols used to communicate between mail servers and send mail (SMTP, SMTPS) and then there’s a database of mail and user information. In OS X Server 5 for El Capitan and Yosemite, all of these are represented by a single ON button, so it really couldn’t be easier. But then there’s the ecoysystem and the evil spammers. As a systems administrator of a large number of mail servers, I firmly believe that there is a special kind of hell where only spam is served at every meal for spammers. Here, the evil spammers must also read every piece of spam ever sent for eternity. By the end (aka Ragnarok), they should have the chemically induced stamina of a 16 year old with the latest Sports Illustrated Swimsuit issue, enough pills of other types to not be able to use that stamina, plenty of African princes looking to donate large sums of money if only they can be helped out of their country (which should cost about 100,000 compared to a 5,000,000 payout, not a bad ROI, right?!?!?), have their conflicting stamina situation at the top of the search engines and of course, have lost all of the money made from their African princes due to getting their credit card hijacked by about 9,000 phishing scams. All in all, a special kind of hell…  But back to the point of the article, setting up mail. The things that mail administrators need to focus on to keep that mail server flowing mail to and from everyone else in the world:
  • Static IP address. The WAN (and LAN probably) address should be static.
  • Port Forwards. Port forwards need to be configured on the gateway for the SMTP port at a minimum and more than likely other ports used to access mail on client devices (25, 143, etc)
  • DNS records. An MX record and some kind of mail.domain.com type of record should definitely be configured for the DNS servers that are authoritative for the domain. There should also be reverse records for the address of the server, usually created by the Internet Services Provider, or ISP, that match that record.
  • Check the RBLs. If you have a new IP address you’ll be putting a DNS server on, check all the major Realtime BlackLists to make sure that some evil spammer hasn’t squatted on the IP before you got to it. This is true whether you’re in a colo, hosted on an IP you own or moving into space formerly occupied by a very standup company. A lot of IP addresses are blocked, as are blocks of IPs, so before moving mail to an IP, check it.
  • Mail filtration (message hygiene). OS X Server has a number of mail filters built in, including clam for viruses, the ability to leverage RBLs, block specific addresses and of course RBL checking. However, this is often not enough. Third party services such as MXLogic help to keep mail from coming into your network. You also end up with an external IP to send mail that can cache mail in the event the server is down and keep mail off your network in the event that it’s spam.
  • Backup. I am firmly of the belief that I’d rather not have data than not have that data backed up…
Once all of that is taken care of (I’ll add more as I think about it) then it’s time to enable the mail service in the Server app running on Yosemite. Actually, first let’s setup our SSL certificates. To do so, open the Server app and click on Certificates in the SERVER section of the sidebar. Here, use the “Secure services using” drop-down list and click on Custom… for each protocol to select the appropriate certificate to be used for the service. Screen Shot 2015-09-22 at 11.16.20 PM Click OK when they’re all configure. Now let’s enable the mail service (or outsource mail). To do so, open the Server app and click on Mail in the SERVICES list in the sidebar. Mail2 At the configuration screen is a sparse number of settings:
  • Domains: Configures all of the domains the mail server will listen for mail for. Each account on the server has a short name and each domain name will be available for each short name. For example, an account with a shortname of charles will be available for email addresses of charles@pretendco.com and charles@krypted.com per the Domain Name listing below.Screen Shot 2015-09-22 at 11.17.27 PM
  • Authentication: Click Edit for a list of sources that accounts can authenticate against (e.g. Active Directory, Open Directory, Custom, Local, etc) and in some cases the specific password algorithms used for mail.Screen Shot 2015-09-22 at 11.18.12 PM
  • Push Notifications: If Push is configured previously there’s no need to use this option. Otherwise, use your institutional APNS account to configure Push Notifications.Screen Shot 2015-09-22 at 11.18.44 PM
  • Relay outgoing mail through ISP: Provide a server that all mail will get routed through from the server. For example, this might be an account with your Internet Services Provider (ISP), an account on an appliance that you own (such as a Barracuda) or with an external filtering service (such as MXLogic).Screen Shot 2015-09-22 at 11.19.42 PM
  • Limit mail to: Configure the total amount of mail a user can have in the mail store, in Megabytes.
  • Edit Filtering Settings: Configure antivirus, spam assassin and junk mail filters. The “Enable virus filtering” checkbox enables clam. The “Enable blacklist filtering” checks the RBL (or RBLs) of your choice to check whether a given server is a “known” spammer and the “Enable junk mail filtering” option enables spam assassin on the host, configuring it to block based on a score as selected using the slider.
Once you’ve configured the settings for the Mail service, click on the ON slider to enable the service. At this point, you should be able to telnet into port 25 of the host to verify that SMTP is listening, preferably from another mail server: telnet mail.krypted.com 25 You can also check that the mail services are running using the serveradmin command along with the fullstatus option for the mail service: sudo serveradmin fullstatus mail Which returns with some pretty verbose information about the service, including state, connections, running protocols and the rest of the following: mail:startedTime = ""
mail:setStateVersion = 1
mail:state = "STOPPED"
mail:protocolsArray:_array_index:0:status = "ON"
mail:protocolsArray:_array_index:0:kind = "INCOMING"
mail:protocolsArray:_array_index:0:protocol = "IMAP"
mail:protocolsArray:_array_index:0:state = "STOPPED"
mail:protocolsArray:_array_index:0:service = "MailAccess"
mail:protocolsArray:_array_index:0:error = ""
mail:protocolsArray:_array_index:1:status = "ON"
mail:protocolsArray:_array_index:1:kind = "INCOMING"
mail:protocolsArray:_array_index:1:protocol = "POP3"
mail:protocolsArray:_array_index:1:state = "STOPPED"
mail:protocolsArray:_array_index:1:service = "MailAccess"
mail:protocolsArray:_array_index:1:error = ""
mail:protocolsArray:_array_index:2:status = "ON"
mail:protocolsArray:_array_index:2:kind = "INCOMING"
mail:protocolsArray:_array_index:2:protocol = "SMTP"
mail:protocolsArray:_array_index:2:state = "STOPPED"
mail:protocolsArray:_array_index:2:service = "MailTransferAgent"
mail:protocolsArray:_array_index:2:error = ""
mail:protocolsArray:_array_index:3:status = "ON"
mail:protocolsArray:_array_index:3:kind = "OUTGOING"
mail:protocolsArray:_array_index:3:protocol = "SMTP"
mail:protocolsArray:_array_index:3:state = "STOPPED"
mail:protocolsArray:_array_index:3:service = "MailTransferAgent"
mail:protocolsArray:_array_index:3:error = ""
mail:protocolsArray:_array_index:4:status = "OFF"
mail:protocolsArray:_array_index:4:kind = "INCOMING"
mail:protocolsArray:_array_index:4:protocol = ""
mail:protocolsArray:_array_index:4:state = "STOPPED"
mail:protocolsArray:_array_index:4:service = "ListServer"
mail:protocolsArray:_array_index:4:error = ""
mail:protocolsArray:_array_index:5:status = "ON"
mail:protocolsArray:_array_index:5:kind = "INCOMING"
mail:protocolsArray:_array_index:5:protocol = ""
mail:protocolsArray:_array_index:5:state = "STOPPED"
mail:protocolsArray:_array_index:5:service = "JunkMailFilter"
mail:protocolsArray:_array_index:5:error = ""
mail:protocolsArray:_array_index:6:status = "ON"
mail:protocolsArray:_array_index:6:kind = "INCOMING"
mail:protocolsArray:_array_index:6:protocol = ""
mail:protocolsArray:_array_index:6:state = "STOPPED"
mail:protocolsArray:_array_index:6:service = "VirusScanner"
mail:protocolsArray:_array_index:6:error = ""
mail:protocolsArray:_array_index:7:status = "ON"
mail:protocolsArray:_array_index:7:kind = "INCOMING"
mail:protocolsArray:_array_index:7:protocol = ""
mail:protocolsArray:_array_index:7:state = "STOPPED"
mail:protocolsArray:_array_index:7:service = "VirusDatabaseUpdater"
mail:protocolsArray:_array_index:7:error = ""
mail:logPaths:Server Error Log = "/Library/Logs/Mail/mail-err.log"
mail:logPaths:IMAP Log = "/Library/Logs/Mail/mail-info.log"
mail:logPaths:Server Log = "/Library/Logs/Mail/mail-info.log"
mail:logPaths:POP Log = "/Library/Logs/Mail/mail-info.log"
mail:logPaths:SMTP Log = "/var/log/mail.log"
mail:logPaths:List Server Log = "/Library/Logs/Mail/listserver.log"
mail:logPaths:Migration Log = "/Library/Logs/MailMigration.log"
mail:logPaths:Virus Log = "/Library/Logs/Mail/clamav.log"
mail:logPaths:Amavisd Log = "/Library/Logs/Mail/amavis.log"
mail:logPaths:Virus DB Log = "/Library/Logs/Mail/freshclam.log"
mail:imapStartedTime = ""
mail:postfixStartedTime = ""
mail:servicePortsRestrictionInfo = _empty_array
mail:servicePortsAreRestricted = "NO"
mail:connectionCount = 0
mail:readWriteSettingsVersion = 1
mail:serviceStatus = "DISABLED" To stop the service: sudo serveradmin stop mail And to start it back up: sudo serveradmin start mail To configure some of the settings no longer in the GUI from previous versions, let’s look at the full list of options: sudo serveradmin settings mail One that is commonly changed is the subject line added to messages that are marked as spam by spam assassin. This is stored in mail:postfix:spam_subject_tag, so changing would be: sudo serveradmin settings mail:postfix:spam_subject_tag = "***DIEEVILSPAMMERSDIE*** " A number of admins also choose to disable greylisting, done using the mail:postfix:greylist_disable option: sudo serveradmin settings mail:postfix:greylist_disable = no To configure an email address for quarantined mail to go, use mail:postfix:virus_quarantine: sudo serveradmin settings mail:postfix:virus_quarantine = "diespammersdie@krypted.com" The administrator, by default, doesn’t get an email when an email containing a file infected with a virus is sent through the server. To enable this option: sudo serveradmin settings mail:postfix:virus_notify_admin = yes I also find a lot of Mac environments want to accept email of pretty much any size. By default, message size limits are enabled. To disable: sudo serveradmin settings mail:postfix:message_size_limit_enabled = yes Or even better, just set new limit: sudo serveradmin settings mail:postfix:message_size_limit = 10485760 And to configure the percentage of someone’s quota that kicks an alert (soft quota): sudo serveradmin settings mail:imap:quotawarn = 75 Additionally, the following arrays are pretty helpful, which used to have GUI options:
  • mail:postfix:mynetworks:_array_index:0 = “127.0.0.0/8″ – Add entries to this one to add “local” clients
  • mail:postfix:host_whitelist = _empty_array – Add whitelisted hosts
  • mail:postfix:blacklist_from = _empty_array – Add blacklisted hosts
  • mail:postfix:black_hole_domains:_array_index:0 = “zen.spamhaus.org” – Add additional RBL Servers
The client side of the mail service is straight forward enough. If you are wondering where in this article we discuss using webmail, er, that’s not installed by default any longer. But the open source project previously used, roundcube, is still available for download and easily installed (the pre-reqs are all there, already). Check out the roundcube wiki installation page here for more info on that. Also, mail groups. I hope to have a post about that soon enough. Unless, of course, I get sidetracked with having a life. Which is arguably not very likely…

September 24th, 2015

Posted In: Mac OS X Server

Tags: , , , , , , , , , , , , ,

A blog is a stream of conscious.  To some degree, so is an rss feed.  If you are browsing it in rss then your reader will more than likely allow you to limit which articles you wish to see based on their tags or other information gleaned from the rss feed.  For example, you can use feed://krypted.com/feed to access this page without graphics, which looks at the rss feed rather than the richer media content, including the css and other elements that cause graphics and the such to appear on the site. You can then limit your results to any field that is specified in the index.rss file.  In this case, you may choose to say, limit to the articles which I have tagged with Xsan.  To do so, you would append a ? to indicate that you are searching for content, followed by the field that you will be searching which is in this case the word tag.  Then you need to specify what you are searching for; for example, tag=xsan would limit the results to only articles which have been tagged as being about Xsan.  Searches are literal, presenting a good argument why spaces and special characters should not be used when tagging assets. You can then perform compound searches.  To search for content that matches two different tags you would use an ampersand (&) to delimit the searches.  For example, you could do feed://krypted.com/feed?tag=xsan&tag=unix which would search for all articles tagged as Xsan and Unix. A number of solutions are based on the concept of an rss (or at least atom) feed.  For example, Podcast Producer submits data to the weblog services of Mac OS X which can then be viewed as a feed rather than using the nice graphical interface that Apple provides (which is by the way very fast).  You can also use rss with Final Cut Server (with a lot of tinkering) and with WordPress and a number of other popular sites.  While I used the example of tag= above, this is not specified as part of the RFC spec for rss and so might not work across all rss engines, although it does work with weblog and WordPress, the CMS that this site is built on.  Twitter and a number of other sites rely on and foster rss as part of their architecture and APIs. The rss feed option therefore opens up endless possibilities for flexible integration between solutions by parsing feeds and even aggregating multiple feeds.  In companies, this can allow you to have a news feed that is integrated into, for example, a SharePoint server.  This might be useful if you have an announcement that has been tagged for only specific offices.  Each staff member might have a feed in their portal splash page that only displays items tagged for their office, their position title or even their department.  I would assume that a new national medical record solution will be a feed and each doctor that a patient visits will view those records in a feed (it’s lightweight and can have links to actual files such as x-rays, scanned/signed insurance forms, etc).  In educational institutions this opens up the possibility of aggregating feeds from multiple Mac OS X Servers running Podcast Producer or the wiki+blog services into a course management solution, such as Moodle, Blackboard or D2L. Aggregation will more than likely have a resounding impact on how we access and how we ultimately find relevant content.  You can subscribe to a Twitter feed, to YouTube, Digg and limit your results to those that match patterns that are consistent with what you are interested in displaying.  But aggregation of content when it is not appropriate or not acceptable can lead to issues with digital rights.  This is one of the key aspects of what the Associated Press has a problem with right now.  One solution they have come up with is to inject information into feeds which then can help track potential aggregators (which is according to their acceptable use policy, against the law).  Other organizations want you to use their RSS feeds, but to only show the first paragraph or so of content, linking to the original site for the full article.  They are saying yes, please link to our content so that we can have more subscribers, but please do not display our entire articles, or if you do please pay us a royalty for having done so. If you own all of the content though, digital rights of the assets (aka articles) is not an issue.  But whose job is it to make sure that you own all of the assets.  How do you track which of those assets are yours?  How do you limit the content that is appropriate for each user in your organization so as not to incur massive quantities of white noise, but still give the power to inform users and readily access content?  These are all questions that creators of a lot of data will be asking (if they are not already) and there is no magic answer to any of these questions.  The key though, is to think of the questions and how they relate to you.

August 7th, 2009

Posted In: sites, Social Networking, WordPress

Tags: , , , , , , ,