index_132
Router Security Configuration Guide
UNCLASSIFIED
132
UNCLASSIFIED
Version 1.0g
2. Viewing the current route table –
To view the current route ta ble, use the command show ip route.
Depending on the size of the network and the kinds of routing protocols
used, this list may be very large. A very important part of reviewing the
route table is checking the route codes and checking the destination
gateway. Each route code identifies how one route joined the table; the
destination gateway is simply the next hop on that route. Check the route
codes to make sure that all the routes joined the table either directly
(code C), or were added as static routes (code S), or were added by a
configured routing protocol (codes R, O, and others, see Section 4.4).
The figure below shows how to interpret the output of show ip route.
Figure 4-8: Interpreting Route Table Output
3. Viewing the routing protocols in use –
The command show ip protocol gives a verbose listing of the route
update mechanisms currently used on the router. The output is different
for each kind of protocol. The command show ip protocol
summary gives a quick overview. All of the individual routing protocols
also have extensive status commands, see Section 4.4 for some
recommendations. The example below shows the IP routing protocol
summary and the output for a useful OSPF status command
(abbreviated).
Central# show ip protocol summary
Index Process Name
0 connected
1 static
2 ospf 1
3 rip
Central# show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
14.2.1.20 1 FULL/DR 00:00:33 14.2.1.20 Eth0/0
14.2.1.250 1 FULL/DR 00:00:38 14.2.1.250 Eth0/0
Central#
Gateway of last resort is 14.1.1.250 to network 0.0.0.0
O IA 7.0.0.0/8 [110/12] via 14.1.1.250, 2d18h, Ethernet0/0
O IA 7.0.0.0/8 [110/14] via 14.1.1.250, 2d18h, Ethernet0/0
O 172.18.0.0/16 [110/11] via 14.1.1.250, 1d13h, Ethernet0/0
C 14.1.0.0/16 is directly connected, Ethernet0/0
O E2 14.2.6.0 [110/10] via 14.1.1.20, 1d01h, Ethernet0/0
C 14.2.9.0 is directly connected, Ethernet0/1
R 14.2.10.0 [120/1] via 14.2.9.64, 00:01:05, Ethernet0/1
O*E2 0.0.0.0/0 [110/3] via 14.1.1.250, 2d19h, Ethernet 0/0
Route codes
Destination
gateways
