6.5

Table Of Contents
Restrict Secure Shell Access
As part of your system hardening process, restrict Secure Shell (SSH) access by conguring the
tcp_wrappers package appropriately on all VMware virtual appliance host machines. Also maintain
required SSH key le permissions on these appliances.
All VMware virtual appliances include the tcp_wrappers package to allow tcp-supported daemons to
control the network subnets that can access the libwrapped daemons. By default, the /etc/hosts.allow le
contains a generic entry, sshd: ALL : ALLOW, that allows all access to the secure shell. Restrict this access as
appropriate for your organization.
Procedure
1 Open the /etc/hosts.allow le on your virtual appliance host machine in a text editor.
2 Change the generic entry in your production environment to include only the local host entries and the
management network subnet for secure operations.
sshd:127.0.0.1 : ALLOW
sshd: [::1] : ALLOW
sshd: 10.0.0.0 :ALLOW
In this example, all local host connections and connections that the clients make on the 10.0.0.0 subnet
are allowed.
3 Add all appropriate machine identication, for example, host name, IP address, fully qualied domain
name (FQDN), and loopback.
4 Save the le and close it.
Maintain Secure Shell Key File Permissions
To maintain an appropriate level of security, congure Secure Shell (SSH) key le permissions.
Procedure
1 View the public host key les, located in /etc/ssh/*key.pub.
2 Verify that these les are owned by root, that the group is owned by root, and that the les have
permissions set to 0644.
The permissions are (-rw-r--r--).
3 Close all les.
4 View the private host key les, located in /etc/ssh/*key.
5 Verify that root owns these les and the group, and that the les have permissions set to 0600.
The permissions are (-rw-------).
6 Close all les.
Harden the Secure Shell Server Configuration
Where possible, the Virtual Application Installation (OVF) has a default hardened conguration. Users can
verify that their conguration is appropriately hardened by examining the server and client service in the
global options section of the conguration le.
If possible, restrict use of the SSH server to a management subnet in the /etc/hosts.allow le.
Chapter 3 Secure Configuration of vRealize Operations Manager
VMware, Inc. 17