Slide #9

Verify that management VLAN has been
Verify that operational VLANs do not have
access to the management VLAN.
Verify that the ports in the management VLAN
are not configured as trunks.
A trunk is a point-to-point link between two
network devices that carries traffic for more than
one VLAN.
A trunk allows you to extend the VLANs across
an entire network.
A trunk does not belong to a specific VLAN,
rather it is a conduit for VLANs between switches
and routers.
DTP is implemented by default on Cisco switches .
DTP automatically negotiates how the port will
operate, trunk or access mode.
By default, a Cisco Ethernet port's default DTP
mode is "dynamic desirable”, which enables a port
to go to trunk mode automatically.
Review the switch configuration to verify that DTP is
VTP is a Cisco-proprietary messaging protocol used
to distribute VLAN configuration information over
A switch may be in one of three VTP modes: server,
transparent and client.
In server mode administrators can create, modify and
delete VLANs for the entire VTP management
By default, VTP – no authentication and the switch is
in VTP Server mode.
If VTP is necessary, verify the following:
• VTP management domain is established.
• A strong password is assigned to the VTP
management domain.
• Non-management switches are configured in
client mode.
By auditing device for these basic hardening steps,
overall security of the network can be improved.
However, in all cases, a comprehensive review
should be performed.
Reference the works cited page for links to
documented security configuration benchmarks
and checklists.
Mark Krawczyk
Router Security Guidance Activity of the System and Network Attack Center (SNAC),
Cisco IOS Switch Security Configuration Guide,
Center for Internet Security,
Information Assurance Support Environment,
SANS Institute InfoSec Reading Room - Cisco Router Hardening Step-by-Step
Cisco Checklist -
Configuring a Cisco Router with TACACS+ Authentication.
Cisco Guide to Harden Cisco IOS Devices, Document ID: 13608
Various Articles related to Cisco device security,
NIST – National Vulnerability Database