Tag Archives: E-mail

CLI, Web

Configure Zimbra live replication

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I’ve recently configured live active replication from my Zimbra e-mail server to a backup server. This is really slick – in the event of primary server failure, I can bring up my secondary in a matter of minutes with no data loss. I used the Zimbra live sync scripts on Gitlab to accomplish this.

These are my notes on things I needed to do in addition to the readme to get things to work properly on my Zimbra 8.8.15 Open Source Edition installs on CentOS 7 boxes.

Install atd (at package):
sudo yum install atd

Make sure the backup server has the same firewall rules as the primary: https://wiki.zimbra.com/wiki/Ports

On the backup server, configure DNS for the mail server to resolve to the Backup server’s IP address. hostname: mail.server.dns -> mirror mail server.

Disable DNS forwarding for primary mail server domain if configured (to ensure mail goes to backup server in the event of switchover.)

Clone over prod mail server, spin up and change network settings:

  • keep hostname (important)
  • change IP, DNS, hosts to use new IP address/network

/etc/sysconfig/network-scripts/ifcfg-eth0
/etc/hosts
/etc/resolv.conf

Ensure proper VLAN settings in backup VM (may be different than primary)

Systemd service:
add Environment=PATH=/opt/zimbra/bin:/opt/zimbra/common/lib/jvm/java/bin:/opt/zimbra/common/bin:/opt/zimbra/common/sbin:/usr/sbin:/sbin:/bin:/usr/sbin:/usr/bin
WorkingDirectory=/opt/zimbra

Remove start argument from ExecStart: ExecStart=/opt/zimbra/live_sync/live_syncd

This is the complete systemd unit for live sync:

[Unit]
Description=Zimbra live sync - to be run on the mirror server
After=network.target

[Service]
ExecStart=/opt/zimbra/live_sync/live_syncd
ExecStop=/opt/zimbra/live_sync/live_syncd kill
User=zimbra
Environment=PATH=/opt/zimbra/bin:/opt/zimbra/common/lib/jvm/java/bin:/opt/zimbra/common/bin:/opt/zimbra/common/sbin:/usr/sbin:/sbin:/bin:/usr/sbin:/usr/bin
WorkingDirectory=/opt/zimbra

[Install]
WantedBy=multi-user.target

Time limit

It looks like there’s a time limit for how long Zimbra keeps redo logs. It means you will get a lost mail situation if you try to bring your primary server back up after it’s been offline for too long (more than a few weeks.) If you’ve been failed over to your secondary mail server for more than two weeks, you’ll want to do the reverse procedure – clone the backup to the primary, edit IP addresses, then run the zimbra live sync. Log into the restored server to ensure mails from greater than 2 weeks ago are all there.

CLI, Web

Fix cron output not being sent via e-mail

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I had an issue where I had cron jobs that output data to stdout, yet mail of the output was never delivered. Everything showed fine in cron.log :

Aug  3 21:21:01 mail CROND[10426]: (nicholas) CMD (echo “test”)
Aug  3 21:21:01 mail CROND[10424]: (nicholas) CMDOUT (test)

yet no e-mail was sent. I finally found out how to fix this in a roundabout way. I came across this article on cpanel.net on how to silence cron e-mails. I then thought I’d try the reverse of a suggestion and add MAILTO= variable at the top of my cron file. It worked! Example crontab:

MAILTO=”youremail@address.com”
0 * * * * /home/nicholas/queue-check.sh

This came about due to my Zimbra box not sending system e-mails. In addition to the above, I had to configure zimbra as a sendmail alternative per this Zimbra wiki post: https://wiki.zimbra.com/wiki/How_to_%22fix%22_system%27s_sendmail_to_use_that_of_zimbra

Web

Zimbra expired ldap certificate fix

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I started getting SSL errors with my Zimbra mail server despite having a valid SSL certificate everywhere I knew where to check. When I tried to use zmcontrol status I got this error:

Unable to start TLS: SSL connect attempt failed error:14090086:SSL routines:ssl3_get_server_certificate:certificate verify failed when connecting to ldap master.

Eventually I found this blog post explaining the problem – it’s with the LDAP component in Zimbra. You have to switch it from ldap to ldaps. Why did this change? I do not know.

ZIMBRA_HOSTNAME=_your_mail_server_dns_hostname_

sudo -u zimbra bash
zmlocalconfig -e ldap_master_url=ldaps://$ZIMBRA_HOSTNAME:636
zmlocalconfig -e ldap_url=ldaps://$ZIMBRA_HOSTNAME:636
zmlocalconfig -e ldap_starttls_supported=0
zmlocalconfig -e ldap_port=636
zmcontrol stop
zmcontrol start

This did the trick. The errors went away.

Networking, OS

Fix POP/SMTP not working in Sophos UTM

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It all started with an innocent enough e-mail:

Data Disk is filling up - please check. Current usage: 100%

I couldn’t find any clear information about what to do about this on Sophos’ forums. My data disk was full. What to do?

I can tell you what not to do – delete random files. I thought my solution would be to log into the UTM’s console and run a du -hsx /* to see where the space was. I found a large folder inside /var/storage – /var/storage/cores/httpd.16438. I removed it, because why not?

It turns out that did some weird things to my UTM. After removing that folder I kept getting spammed with these e-mails, once every hour:

Pop3 proxy not running - restarted

It took me a while to realize, but this also meant all e-mails relayed to the UTM were not being delivered. The entire POP/SMTP subsystem of the Sophos UTM was hosed. I could not find anything on the Sophos forums. After scratching my head I decided to have a deeper look at the logs. From the command line I issued

ls -ltr /var/log

and began reading the most recent logs.

pop3.log let me know what the problem was:

pop3proxy[9270]: Can't connect to database, retrying in 10 seconds: could not connect to server: Connection refused

I could not find any useful fixes for this error. I kept digging.

selfmon.log wasn’t much help other than to confirm that pop3 was having some serious issues. It was an endless abyss of repeated error messages:

selfmonng[3818]: W NOTIFYEVENT Name=pop3proxy_running Level=INFO Id=117 suppressed
...
selfmonng[3818]: W actionCmd(+): '/var/mdw/scripts/pop3 restart'

system.log put me on the right track:

ulogd[5107]: pg1: connect: could not connect to server: No such file or directory

 

Finally, we’re getting somewhere! After some searching I learned that pg1 is the postgresql database Sophos uses. I found a way to rebuild from this forum post.

One simple command did the trick:

/etc/init.d/postgresql92 rebuild

This rebuilt the postgresql database that I apparently corrupted when I removed files with reckless abandon. My e-mails work again!

Web

Configure Sophos UTM to forward e-mail for internal clients

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If you’re in a situation like mine you have an ISP which stubbornly blocks port 25. You can get around this by using SSL/TLS of course but configuring each server can be a pain. The solution, in my case, is to turn my UTM into an e-mail relay server and simply have each node point to it for SMTP.

The process wasn’t as straightforward as I had hoped. Below are the steps to accomplish this:

First, enable the SMTP proxy by going to E-mail Protection / SMTP.

Next, go to the Relaying tab and configure allowed relay hosts. For my setup I went to the Host-based relay section and added each individual host that I want to have use my UTM for e-mail relaying.

Lastly, you must configure your UTM to send e-mails out to your ISP’s mail relay since by default the UTM tries to send e-mails out itself on port 25, which in my case is blocked. Do this by going to the Advanced tab and scrolling down to smart host settings. Configure the mail relay server, credentials, and port required there.

That part was fairly straightforward; however the spam protection feature of the UTM was preventing any messages sent to the UTM from being sent to the internet.

After much weeping, wailing and gnashing of teeth (including adding an SPF record for my domain) I discovered that the solution was to ensure that outgoing mail shows the node’s name in the From: field. If your server’s name is server, the from should always be server@yourdomain.org. I haven’t dug into why, but oh well! It works.