Table 4-8 show ip arp Command Output Fields (Continued)
Field Description
Understanding Cisco Router Security 305
The command syntax is described in Table 4-10.
Summary of Exploring the Packet Delivery Process
The following list summarizes the key points that were discussed in the previous sections:
?– If the hosts are not on the same segment, the frame is sent to the default gateway.
?– Packets sent to the default gateway will have the local host source and remote host
destination IP address.
?– Frames sent to the default gateway will have the local host source and the default
gateway MAC address.
?– A router will change the Layer 2 address as needed but will not change the Layer
3 address.
?– The show ip arp command displays the mapping between network addresses and
MAC addresses that the router has learned.
?– IOS connectivity tools:
??” Ping
??” Traceroute
Understanding Cisco Router Security
After you secure physical access to your network, you must ensure that access to the
Cisco router through the console and vty ports is secure. In addition, you must ensure that
unused router ports do not become a security risk. The following sections describe router
security.
Table 4-10 traceroute Command Syntax Description
Syntax Description
protocol (Optional) Protocol keyword: appletalk, clns, ip, ipv6, ipx, oldvines, or
vines.
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