ISACA – Charlotte Chapter
June 3, 2014
Mark Krawczyk, CISA, CISSP, CCNA
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Routers and Switches direct and control much of
the data flowing across computer networks.
The services provided are critical to the proper
functioning and secure operations of Corporate
networks.
Properly configured secure routers and switches
can greatly improve the overall security posture
of a network.
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Network devices are subject to various attacks:
• Unauthorized access – compromise device, routing
tables, MAC tables.
• Session hijacking - an attacker can insert falsified IP
packets after session establishment via IP spoofing.
• Rerouting - manipulating router updates to cause traffic
to flow to unauthorized destinations (route injection).
• Masquerading - manipulates IP packets to falsify IP
addresses.
• Denial of Service (DoS) - flooding the router with traffic
or requests designed to consume all of some limited
resource.
• Eavesdropping – insecure protocols, packet sniffers
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Routing is accomplished using the IP addresses of
the source and destination hosts and intermediary
network devices such as Routers or Multilayer
switches.
The router examines the destination network address
for each packet and then checks the routing table for
forwarding information.
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The routing table stores information about connected
and remote networks.
• Connected networks are directly attached to one of the
router interfaces.
• Remote networks are not directly connected to the
router. Routes to these networks can be manually
configured on the router or learned automatically using
dynamic routing protocols.
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Static Routing - Routes to remote networks are
manually configured on the router. A default route can
be statically configured.
Dynamic Routing- As routers become aware of
changes to the networks this information is passed
on to other routers. When a router receives
information about new or changed routes, it updates
its own routing table and, in turn, passes the
information to other routers.