Security of your NeCTAR instances is your responsibility. The following list provides some suggested checks to help you keep your instances secure.


  • Check-Security-01: Is SSH password login disabled?

    With enough time and compute power it is possible for passwords to be brute force attacked. The average SSH server deals with thousands of such attacks every week, so use SSH keys.
  • Check-Security-02: Are you running a mail server?

    If you want to run a mail server in Nectar Virtual Machine, make sure it only listens on Localhost (127.0.0.1).

  • Check-Security-03: Are automatic updates enabled?

Check that automatic updates are enabled in the operating system.

  • Check-Security-04: Have you upgraded the operating system kernel?

Check whether your operating system kernel is the latest. Kernel upgrade requires reboot and you need to schedule this into regular maintenance.

  • Check-Security-05: Are you running DNS service?

If you are running a DNS server, ensure you only allow recursion from trusted hosts.

  • Check-Security-06: Are you running NTP service?

If you run a NTP server, limit which systems can access it. Disable the 'monlist' command as this can be used as a denial of service vector on your system.

  • Check-Security-07: Have you subscribed to security announcements?

If there is a security problem with your operating system, you need to find out as soon as possible. Find the appropriate mailing list and keep an eye out for anything that requires urgent action. As soon as new security bugs are detected, you need to execute security upgrade immediately.

  • Check-Security-08: Is a host-based firewall running?

Virtual machine should be configured so they allow the minimum access required to run their service. Please use a host-based firewall, in conjunction with the cloud-provided firewall to manage access.

  • Check-Security-09: Are there any unneeded accounts in the system?

Keep an eye on the user accounts enabled on your system. Some applications create default accounts which are insecure. You may also open a temporary user account to allow quick login for a task and leave it forever. This may lead to security issue later, and you need to regular check and delete these user accounts.


  • Check-Security-10: Are keys stored in the image?

The cloud provides a metadata service so you can download keys on boot, so you don't need to copy keys manually. This ensures that if your key is compromised, not all running instances of that image are compromised.

  • Check-Security-11: Is an SSH attack banning tools installed?

Install a tools like fail2ban or denyhosts, which checks log files for attempted breaches and then blocks malicious IP addresses.

  • Check-Security-12: Are unneeded services disabled?

Know what services run on your virtual machine, and disable the unneeded ones.

  • Check-Security-13: Are encrypted communications used?

Wherever possible, use encrypted communications to avoid attacks which intercept data.

  • Check-Security-14: Is logging stored in a secure place?

Make sure that services are logging to a secure location, that is as tamperproof as possible. If logging remotely, ensure that it is done over a secure channel so that eavesdroppers cannot monitor what is happening on your instance.

  • Check-Security-15: Are ports opened for not required services?

By default, virtual machines in NeCTAR have all ports closed, so in order to make a service available to public, you need to open certain ports for it. Before you open a port, you need to think carefully about what service is associated with it and what is the intention. Never open a port without a service bound to it.

  • Check-Security-16: What permission granted to user account?

When creating a user account, make sure only permission sufficient for its use is granted. Never grant extra permission if it is not needed.

  • Check-Security-17: Is root access disabled from SSH?

Disable root user SSH login and setup a user account with sudo permission to perform administrator tasks.

  • Check-Security-18: Are other ports used for SSH?

The SSH service on the virtual machine uses port 22 by default. This port is well-known and can attract many attackers. Using a custom ssh port other than 22 will improve security. Be noted, the port number below 1024 is well reserved and shouldn't be used for SSH.