© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-1 Implementing an EIGRP-Based Solution Implementing and Verifying EIGRP Authentication

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-2 Router Authentication  Implement security to the routing protocol by supporting authentication  A router authenticates the source of each routing update packet that it receives.  Prevent false routing updates from updating the routing table: –Prevent deliberate false routing updates sourced by unapproved sources –Ignore malicious updates, thus preventing them from disrupting the routing or taking down the adjacency

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-3 Router Authentication (Cont.)  Many routing protocols support authentication  Simple password authentication is supported by: –OSPF –RIPv2  MD5 authentication is supported by: –EIGRP –OSPF –RIPv2 –BGP

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-4 Simple Password vs. MD5 Authentication  Simple password authentication: –The router sends a packet and a key. –The neighbor checks if the key matches its key. –The process is not secure.  MD5 authentication: –This authentication is secure, as described in RFC1321. –This authentication does not include confidentiality (content not encrypted). –The router generates a message digest. –The message digest is sent with the packet. –The key is not sent.

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-5 MD5 Authentication for EIGRP  EIGRP supports MD5 authentication.  The router generates a MD5 message digest. –Multiple keys can be configured in all EIGRP routers.  The receiving router computes the MD5 hash from the received EIGRP information.  Time should be synchronized between all routers, and NTP can be used.

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-6 Key Chain  EIGRP allows keys to be managed using key chains –A key chain is a set of keys associated with an interface. –Includes key IDs, keys, and key lifetimes –The first valid activated key is used in the outgoing direction. –Incoming packets are checked against all valid keys.

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-7 Planning for EIGRP Authentication  Examine the existing EIGRP configuration  Define the authentication type  Define how many keys will be used  Define if an optional lifetime parameter will be used

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-8 Requirements for EIGRP Authentication  EIGRP AS number  Authentication mode  One or more keys  Key lifetimes (optional)

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-9 Steps to Configure EIGRP MD5 Authentication  Configure the authentication mode for EIGRP  Configure the key chain  Configure the lifetime of each key in the key chain  Enable authentication to use the key or keys in the key chain

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-10 Configure Authentication Mode  Specify the type of authentication used in EIGRP packets for router R1 and R2 interface Serial0/0/1 ip authentication mode eigrp 110 md5 md5 R1(config)# interface Serial0/0/1 ip authentication mode eigrp 110 md5 110 md5 R2(config)#

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-11 Configure the Key Chain  Create the key-chain to enter key chain key configuration mode.  Create an authentication key on a key chain.  Define the authentication string for a key (password). key chain routerR1chain key 1 key-string firstkey key 2 key-string secondkey R1(config)# key chain routerR2chain key 1 key-string firstkey key 2 key-string secondkey R2(config)#

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-12 Configure the Lifetime of The Key or Keys  If you wish, you can define when the key will be accepted or sent. key chain routerR1chain key 1 key-string firstkey accept-lifetime 04:00:00 Jan infinite send-lifetime 04:00:00 Jan :00:00 Jan key 2 key-string secondkey accept-lifetime 04:00:00 Jan infinite send-lifetime 04:00:00 Jan infinite R1(config)#

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-13 Enable Authentication of EIGRP Packets  Enable authentication of EIGRP packets using the key or keys in the key chains routerR1chain and routerR2chain on routers R1 and R2, respectively. interface Serial0/0/1 ip authentication key-chain eigrp 110 routerR1chain R1(config)# interface Serial0/0/1 ip authentication key-chain eigrp 110 routerR2chain R2(config)#

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-14 Router R1 Configuration for MD5 Authentication key chain routerR1chain key 1 key-string firstkey accept-lifetime 04:00:00 Jan infinite send-lifetime 04:00:00 Jan :00:00 Jan key 2 key-string secondkey accept-lifetime 04:00:00 Jan infinite send-lifetime 04:00:00 Jan infinite interface FastEthernet0/0 ip address ! interface Serial0/0/1 bandwidth 256 ip address ip authentication mode eigrp 110 md5 ip authentication key-chain eigrp 110 routerR1chain ! router eigrp 110 network network auto-summary R1#

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-15 Verifying MD5 Authentication for EIGRP  Verify that the EIGRP neighbor relationship is up  Verify that the IP routing table is populated R1#show ip eigrp neighbors IP-EIGRP neighbors for process 110 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num Se0/0/ :03: R1#show ip route Gateway of last resort is not set D /16 [90/ ] via , 00:02:22, Serial0/0/ /16 is variably subnetted, 2 subnets, 2 masks D /16 is a summary, 00:31:31, Null0 C /24 is directly connected, FastEthernet0/ /24 is variably subnetted, 2 subnets, 2 masks C /27 is directly connected, Serial0/0/1 D /24 is a summary, 00:31:31, Null0

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-16 Verifying MD5 Authentication for EIGRP (Cont.)  Verify the key chains and keys  This output of the show key chain command is from January 27, R1#show key chain Key-chain routerR1chain: key 1 -- text “firstkey" accept lifetime (04:00:00 Jan ) - (always valid) [valid now] send lifetime (04:00:00 Jan ) - (04:00:00 Jan ) key 2 -- text “secondkey" accept lifetime (04:00:00 Jan ) - (always valid) [valid now] send lifetime (04:00:00 Jan ) - (always valid) [valid now]

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-17 Verifying MD5 Authentication for EIGRP (Cont.)  Use debug to verify the operation R1#debug eigrp packet EIGRP Packets debugging is on (UPDATE, REQUEST, QUERY, REPLY, HELLO, IPXSAP, PROBE, ACK, STUB, SIAQUERY, SIAREPLY) *Jan 21 16:38:51.745: EIGRP: received packet with MD5 authentication, key id = 1 *Jan 21 16:38:51.745: EIGRP: Received HELLO on Serial0/0/1 nbr *Jan 21 16:38:51.745: AS 110, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 pe erQ un/rely 0/0 R2#debug eigrp packet EIGRP Packets debugging is on (UPDATE, REQUEST, QUERY, REPLY, HELLO, IPXSAP, PROBE, ACK, STUB, SIAQUERY, SIAREPLY) R2# *Jan 21 16:38:38.321: EIGRP: received packet with MD5 authentication, key id = 1 *Jan 21 16:38:38.321: EIGRP: Received HELLO on Serial0/0/1 nbr *Jan 21 16:38:38.321: AS 110, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 pe erQ un/rely 0/0

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-18 Misconfigured Key  The MD5 authentication key is different for routers R1 and R2.  The EIGRP neighbor relationship is down. R1#debug eigrp packets EIGRP Packets debugging is on (UPDATE, REQUEST, QUERY, REPLY, HELLO, IPXSAP, PROBE, ACK, STUB, SIAQUERY, SIAREPLY) R1# *Jan 31 23:20:21.967: EIGRP: Sending HELLO on Serial1/0 *Jan 31 23:20:21.967: AS 110, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 *Jan 31 23:20:22.315: EIGRP: pkt key id = 2, authentication mismatch *Jan 31 23:20:22.315: EIGRP: Serial1/0: ignored packet from , opcod e = 5 (invalid authentication) R1#show ip eigrp neighbors IP-EIGRP neighbors for process 110

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-19 Summary  There are two types of router authentication: simple password and MD5 authentication.  When EIGRP authentication is configured, the router generates and checks every EIGRP packet and authenticates the source of each routing update packet that it receives. EIGRP supports MD5 authentication.  To configure MD5 authentication, use the ip authentication mode eigrp and ip authentication key-chain interface commands. The key chain must also be configured to define the keys.  Use show ip eigrp neighbors, show ip route, and debug eigrp packets to verify MD5 authentication.

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-20