Kerio Connect Virtual Appliance Networking (Debian Edition - Kerio Connect 7.3.x and later)

This topic provides information on networking for the Kerio Connect VMware virtual appliance.


This information is provided 'As Is' and that Kerio Technical Support will only be able to help with default values.

First ensure that you are running the Debian variant of Linux. There are several ways to do this, we recommend the use of the following command:

uname -a

The output from this command displays the linux type.

If you are using CentOS, refer to the following topic instead.


The configuration details outlined below require terminal access with the root user.

Working in the console

At the Virtual machine Console Press Alt+F2 to switch the visible console to another terminal (tty) screen within the Virtual machine management Interface.

Where prompted, log in as "root" (without the quote marks). To start with, the default password is "kerio" (without the quote marks). You will be forced to change the password upon first login. Please keep your new password safe, as a forgotten password can NOT be recovered!

Updating the System

Log on to the system console.

First we need to make sure that the operating system is up to date, there are two commands to run to do this:

apt-get update

apt-get dist-upgrade

Working with the Firewall

Kerio Connect Virtual Machine contains a powerful iptables firewall, this is installed on all Linux Servers.

Administrators may use the "ufw" tool to control iptables firewall

You can either set all traffic defaults to allow:

ufw default allow

Or, turn it off altogether:

ufw disable

Or you can allow traffic to a specific port:

ufw allow 8989


For more details please see,

Checking and Editing Virtual Network Adapter Settings.

Linux virtual machines on ESX/ESXi 4.1 using the vmxnet3 virtual adapter may experience a loss of network connectivity when the virtual NIC switches between offline and online.

This may also effect networking Link Speed.

Kerio Connect Virtual Machine is based on Linux.

/var/log/messages or dmesg may contain entries similar to:

kernel: eth0: tq_error 0x80000000

kernel: eth0: resetting

kernel: eth0: intr type 2, mode 0, 1 vectors allocated

kernel: eth0: NIC Link is Up 10000 Mbps

Disable TSO if you are experiencing the above.

  1. Log in as root to the terminal.
  2. To determine the device name of your virtual network card, run the command: ifconfig
  3. To determine your current TSO setting for that adapter, run the command: ethtool -k eth1, where eth1 is the vmxnet3 adapter based on ifconfig output from step 3.
  4. To disable TSO, run the command: ethtool - K eth1 tso off


TSO is used to reduce CPU overhead on TCPTransmission Control Protocol - ensures packet transmission./IP. Disabling TSO may cause higher CPU during high network traffic.