Fixing IMAP Performance Issues

fixing-imap

What are the issues?

In some cases, users of Imunify360 v4.7 can experience issues with IMAP authorization performance. These issues are related to the amount of UDP traffic produced when Imunify360 protects a server against brute force mail attacks.

The issue can be identified by the presence of mass entries similar to this one in /var/log/messages:

Mar 4 20:36:03 jump05 pam_imunify_daemon: 2020/03/04 20:36:03 RBL check: lookup 99.71.43.95.net-brute.rbl.imunify.com. on 79.98.109.15:53: dial udp: i/o timeout

Mitigating the issues

Imunify360 version 4.8 contains the necessary fixes and is already available for update. However, the automatic rollout may take up to nine days. 100% production rollout is expected on Jun 10, 2020.

To mitigate issue in the meantime, we recommend making the following changes in the /etc/pam_imunify/i360.ini file:

Change RBL_timeout from 5 to 3:

RBL_timeout=3
Change RBL_nameserver to your local DNS:

RBL_nameserver=mydns.com:53
Restart Imunify360:

# systemctl restart imunify360-pam

Fixing them immediately

If you don’t want to wait until the rollout process is complete, and you wish to upgrade to Imunify360 version 4.8 immediately, run the following commands:

# wget https://repo.imunify360.cloudlinux.com/defence360/imunify-force-update.sh

# bash imunify-force-update.sh