VPN - GRE over IPsec
Today I would like to play with GRE tunnels and their protections by IPsec profiles. Below you can find scenario I use today:
R3:
!
crypto isakmp policy 10
encr 3des
authentication pre-share
group 5
crypto isakmp key cisco address 0.0.0.0
!
!
crypto ipsec transform-set TS esp-3des esp-sha-hmac
mode tunnel
!
crypto ipsec profile IPSEC-PRF
set transform-set TS
!
interface Tunnel0
ip address 7.7.7.3 255.255.255.0
tunnel source FastEthernet1/0
tunnel destination 10.1.0.5
tunnel protection ipsec profile IPSEC-PRF
!
router eigrp 10
network 7.7.7.0 0.0.0.255
network 10.2.0.0 0.0.0.255
!
And R5:
!
crypto isakmp policy 10
encr 3des
authentication pre-share
group 5
crypto isakmp key cisco address 0.0.0.0
!
!
crypto ipsec transform-set TS esp-3des esp-sha-hmac
mode tunnel
!
crypto ipsec profile IPSEC-PRF
set transform-set TS
!
interface Tunnel0
ip address 7.7.7.5 255.255.255.0
tunnel source FastEthernet0/1
tunnel destination 10.1.0.3
tunnel protection ipsec profile IPSEC-PRF
!
router eigrp 10
network 7.7.7.0 0.0.0.255
network 10.0.0.0 0.0.0.255
!
Let’s check the GRE tunnels status:
r3#sh ip int b
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 10.2.0.3 YES manual up up
FastEthernet0/1 unassigned YES unset administratively down down
FastEthernet1/0 10.1.0.3 YES manual up up
FastEthernet1/1 unassigned YES unset administratively down down
Tunnel0 7.7.7.3 YES manual up up
r3#
r5#sh ip int b
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 10.0.0.5 YES manual up up
FastEthernet0/1 10.1.0.5 YES manual up up
FastEthernet1/0 unassigned YES unset administratively down down
FastEthernet1/1 unassigned YES unset administratively down down
Tunnel0 7.7.7.5 YES manual up up
r5#'
I try now to send ping from R12 to R6 to check if the traffic is encrypted:
r3#sh crypto session detail
Crypto session current status
Code: C - IKE Configuration mode, D - Dead Peer Detection
K - Keepalives, N - NAT-traversal, T - cTCP encapsulation
X - IKE Extended Authentication, F - IKE Fragmentation
Interface: Tunnel0
Uptime: 00:25:26
Session status: UP-ACTIVE
Peer: 10.1.0.5 port 500 fvrf: (none) ivrf: (none)
Phase1_id: 10.1.0.5
Desc: (none)
IKEv1 SA: local 10.1.0.3/500 remote 10.1.0.5/500 Active
Capabilities:(none) connid:1002 lifetime:23:34:22
IKEv1 SA: local 10.1.0.3/500 remote 10.1.0.5/500 Active
Capabilities:(none) connid:1001 lifetime:23:34:20
IPSEC FLOW: permit 47 host 10.1.0.3 host 10.1.0.5
Active SAs: 6, origin: crypto map
Inbound: #pkts dec'ed 330 drop 22 life (KB/Sec) 4375496/2082
Outbound: #pkts enc'ed 346 drop 0 life (KB/Sec) 4375497/2082
r3#
r5#sh crypto session detail
Crypto session current status
Code: C - IKE Configuration mode, D - Dead Peer Detection
K - Keepalives, N - NAT-traversal, T - cTCP encapsulation
X - IKE Extended Authentication, F - IKE Fragmentation
Interface: Tunnel0
Uptime: 00:25:51
Session status: UP-ACTIVE
Peer: 10.1.0.3 port 500 fvrf: (none) ivrf: (none)
Phase1_id: 10.1.0.3
Desc: (none)
IKEv1 SA: local 10.1.0.5/500 remote 10.1.0.3/500 Active
Capabilities:(none) connid:1001 lifetime:23:33:54
IKEv1 SA: local 10.1.0.5/500 remote 10.1.0.3/500 Active
Capabilities:(none) connid:1002 lifetime:23:33:57
IPSEC FLOW: permit 47 host 10.1.0.5 host 10.1.0.3
Active SAs: 6, origin: crypto map
Inbound: #pkts dec'ed 338 drop 13 life (KB/Sec) 4357161/2057
Outbound: #pkts enc'ed 358 drop 0 life (KB/Sec) 4357160/2057
r5#
R12#ping 10.0.0.6 repeat 100
Type escape sequence to abort.
Sending 100, 100-byte ICMP Echos to 10.0.0.6, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!
!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!
Success rate is 96 percent (96/100), round-trip min/avg/max = 20/69/136 ms
R12#
And check now the numbers:
r3#sh crypto session detail
Crypto session current status
Code: C - IKE Configuration mode, D - Dead Peer Detection
K - Keepalives, N - NAT-traversal, T - cTCP encapsulation
X - IKE Extended Authentication, F - IKE Fragmentation
Interface: Tunnel0
Uptime: 00:26:51
Session status: UP-ACTIVE
Peer: 10.1.0.5 port 500 fvrf: (none) ivrf: (none)
Phase1_id: 10.1.0.5
Desc: (none)
IKEv1 SA: local 10.1.0.3/500 remote 10.1.0.5/500 Active
Capabilities:(none) connid:1002 lifetime:23:32:57
IKEv1 SA: local 10.1.0.3/500 remote 10.1.0.5/500 Active
Capabilities:(none) connid:1001 lifetime:23:32:54
IPSEC FLOW: permit 47 host 10.1.0.3 host 10.1.0.5
Active SAs: 6, origin: crypto map
Inbound: #pkts dec'ed 444 drop 23 life (KB/Sec) 4375477/1997
Outbound: #pkts enc'ed 465 drop 0 life (KB/Sec) 4375477/1997
r3#
r5#sh crypto session detail
Crypto session current status
Code: C - IKE Configuration mode, D - Dead Peer Detection
K - Keepalives, N - NAT-traversal, T - cTCP encapsulation
X - IKE Extended Authentication, F - IKE Fragmentation
Interface: Tunnel0
Uptime: 00:26:56
Session status: UP-ACTIVE
Peer: 10.1.0.3 port 500 fvrf: (none) ivrf: (none)
Phase1_id: 10.1.0.3
Desc: (none)
IKEv1 SA: local 10.1.0.5/500 remote 10.1.0.3/500 Active
Capabilities:(none) connid:1001 lifetime:23:32:50
IKEv1 SA: local 10.1.0.5/500 remote 10.1.0.3/500 Active
Capabilities:(none) connid:1002 lifetime:23:32:52
IPSEC FLOW: permit 47 host 10.1.0.5 host 10.1.0.3
Active SAs: 6, origin: crypto map
Inbound: #pkts dec'ed 452 drop 14 life (KB/Sec) 4357142/1992
Outbound: #pkts enc'ed 468 drop 0 life (KB/Sec) 4357142/1992
r5#
R12#traceroute 10.0.0.6
Type escape sequence to abort.
Tracing the route to 10.0.0.6
1 10.2.0.3 48 msec 44 msec 36 msec
2 7.7.7.5 76 msec 92 msec 48 msec
3 10.0.0.6 92 msec 56 msec 76 msec
R12#
As you see the traffic is passing through the tunnel and it is encrypted properly. There is one problem with this scenario because I don’t have any tunnel between R12 and R6. I’m going now to add the second tunnel and implement HA.
On r5 I add a new tunnel interface:
r5#sh run int Tun1
Building configuration...
Current configuration : 162 bytes
!
interface Tunnel1
ip address 7.7.8.5 255.255.255.0
tunnel source FastEthernet0/1
tunnel destination 10.1.0.4
tunnel protection ipsec profile IPSEC-PRF
end
r5#
and the same on R4:
r4#sh run int tun1
Building configuration...
Current configuration : 162 bytes
!
interface Tunnel1
ip address 7.7.8.4 255.255.255.0
tunnel source FastEthernet0/1
tunnel destination 10.1.0.5
tunnel protection ipsec profile IPSEC-PRF
end
r4#
Now I check the routing table on both: r12 and r5:
R12#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
7.0.0.0/24 is subnetted, 2 subnets
D 7.7.7.0 [90/26882560] via 10.2.0.3, 02:25:21, FastEthernet1/0
D 7.7.8.0 [90/26882560] via 10.2.0.4, 00:45:48, FastEthernet1/0
10.0.0.0/24 is subnetted, 2 subnets
C 10.2.0.0 is directly connected, FastEthernet1/0
D 10.0.0.0 [90/26885120] via 10.2.0.4, 00:44:19, FastEthernet1/0
[90/26885120] via 10.2.0.3, 00:44:19, FastEthernet1/0
R12#
r5#sh ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
7.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
C 7.7.7.0/24 is directly connected, Tunnel0
L 7.7.7.5/32 is directly connected, Tunnel0
C 7.7.8.0/24 is directly connected, Tunnel1
L 7.7.8.5/32 is directly connected, Tunnel1
10.0.0.0/8 is variably subnetted, 5 subnets, 2 masks
C 10.0.0.0/24 is directly connected, FastEthernet0/0
L 10.0.0.5/32 is directly connected, FastEthernet0/0
C 10.1.0.0/24 is directly connected, FastEthernet0/1
L 10.1.0.5/32 is directly connected, FastEthernet0/1
D 10.2.0.0/24 [90/26882560] via 7.7.8.4, 00:45:08, Tunnel1
[90/26882560] via 7.7.7.3, 00:45:08, Tunnel0
r5#
In my case both physical links are exactly the same. If you need to have one preferred node you can change some eigrp parameters like delay.
Let’s test now the failure of one device:
R12#ping 10.0.0.6 repeat 10000
Type escape sequence to abort.
Sending 10000, 100-byte ICMP Echos to 10.0.0.6, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!
!!!.!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!.!!!!!!!!!!!!!!
!!!!!.!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!.......!!!!!!!!!!!!!!!!!..!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!
.
Success rate is 92 percent (260/281), round-trip min/avg/max = 24/75/184 ms
R12#
r5(config-if)#int tun
*Nov 19 16:44:45.911: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel1, changed state to up0
r5(config-if)#
*Nov 19 16:44:45.935: %LINK-3-UPDOWN: Interface Tunnel1, changed state to upsh
r5(config-if)#
*Nov 19 16:44:49.587: %DUAL-5-NBRCHANGE: EIGRP-IPv4 10: Neighbor 7.7.7.3 (Tunnel0) is down: interface down
*Nov 19 16:44:51.519: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to down
*Nov 19 16:44:51.523: %LINK-5-CHANGED: Interface Tunnel0, changed state to administratively down
*Nov 19 16:44:58.519: %DUAL-5-NBRCHANGE: EIGRP-IPv4 10: Neighbor 7.7.8.4 (Tunnel1) is up: new adjacency
*Nov 19 16:45:01.171: %CRYPTO-4-RECVD_PKT_MAC_ERR: decrypt: mac verify failed for connection id=25 spi=500B46EE seqno=00000007
*Nov 19 16:45:04.987: %CRYPTO-4-IKMP_NO_SA: IKE message from 10.1.0.4 has no SA and is not an initialization offer
As you see I lost 7 packets when I shut down one tunnel. Now the switchover time is dependent on routing protocol characteristic. In my next post I will add HA with stateful switchover (SSO).
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Kudos
8
Kudos