:lastproofread: 2025-06-26 .. _examples-ipsec-cisco-route-based: ######################################################### Route-based Site-to-Site VPN IPsec between VyOS and Cisco ######################################################### This document is to describe a basic setup using route-based site-to-site VPN IPsec. In this example we use VyOS 1.5 and Cisco IOS. Cisco initiates IPsec connection only if interesting traffic present. For stable work we recommend configuring an initiator role on VyOS side. OSPF is selected as routing protocol inside the tunnel. Network Topology ================ .. image:: /_static/images/cisco-vpn-ipsec.png :align: center :alt: Network Topology Diagram Prerequirements =============== **VyOS:** +---------+----------------+ | WAN IP | 10.0.1.2/30 | +---------+----------------+ | LAN1 IP | 192.168.0.1/24 | +---------+----------------+ | LAN2 IP | 192.168.1.1/24 | +---------+----------------+ **Cisco:** +---------+-----------------+ | WAN IP | 10.0.2.2/30 | +---------+-----------------+ | LAN1 IP | 192.168.10.1/24 | +---------+-----------------+ | LAN2 IP | 192.168.11.1/24 | +---------+-----------------+ **IKE parameters:** +-------------------+---------+ | Encryption | AES-128 | +-------------------+---------+ | HASH | SHA-1 | +-------------------+---------+ | Diff-Helman Group | 14 | +-------------------+---------+ | Life-Time | 28800 | +-------------------+---------+ | IKE Version | 1 | +-------------------+---------+ **IPsec parameters:** +------------+---------+ | Encryption | AES-256 | +------------+---------+ | HASH | SHA-256 | +------------+---------+ | Life-Time | 3600 | +------------+---------+ | PFS | disable | +------------+---------+ **Hosts configuration** +--------+--------------+ | PC1 IP | 192.168.0.2 | +--------+--------------+ | PC2 IP | 192.168.1.2 | +--------+--------------+ | PC3 IP | 192.168.10.2 | +--------+--------------+ | PC4 IP | 192.168.11.2 | +--------+--------------+ Configuration ============= .. note:: Pfs is disabled in Cisco by default. VyOS ---- .. code-block:: none set interfaces ethernet eth0 address '10.0.1.2/30' set interfaces ethernet eth1 address '192.168.0.1/24' set interfaces ethernet eth2 address '192.168.1.1/24' set interfaces vti vti1 address '10.100.100.1/30' set interfaces vti vti1 mtu '1438' set protocols ospf area 0 network '10.100.100.0/30' set protocols ospf area 0 network '192.168.0.0/24' set protocols ospf area 0 network '192.168.1.0/24' set protocols ospf interface eth1 passive set protocols ospf interface eth2 passive set protocols ospf interface vti1 network 'point-to-point' set protocols ospf parameters router-id '2.2.2.2' set protocols static route 0.0.0.0/0 next-hop 10.0.1.1 set vpn ipsec authentication psk AUTH-PSK id '10.0.1.2' set vpn ipsec authentication psk AUTH-PSK id '10.0.2.2' set vpn ipsec authentication psk AUTH-PSK secret 'dGVzdA==' set vpn ipsec authentication psk AUTH-PSK secret-type 'base64' set vpn ipsec esp-group ESP-GROUP lifetime '3600' set vpn ipsec esp-group ESP-GROUP pfs 'disable' set vpn ipsec esp-group ESP-GROUP proposal 10 encryption 'aes256' set vpn ipsec esp-group ESP-GROUP proposal 10 hash 'sha256' set vpn ipsec ike-group IKE-GROUP close-action 'start' set vpn ipsec ike-group IKE-GROUP dead-peer-detection action 'restart' set vpn ipsec ike-group IKE-GROUP dead-peer-detection interval '10' set vpn ipsec ike-group IKE-GROUP dead-peer-detection timeout '30' set vpn ipsec ike-group IKE-GROUP key-exchange 'ikev1' set vpn ipsec ike-group IKE-GROUP lifetime '28800' set vpn ipsec ike-group IKE-GROUP proposal 10 dh-group '14' set vpn ipsec ike-group IKE-GROUP proposal 10 encryption 'aes128' set vpn ipsec ike-group IKE-GROUP proposal 10 hash 'sha1' set vpn ipsec options disable-route-autoinstall set vpn ipsec site-to-site peer CISCO authentication local-id '10.0.1.2' set vpn ipsec site-to-site peer CISCO authentication mode 'pre-shared-secret' set vpn ipsec site-to-site peer CISCO authentication remote-id '10.0.2.2' set vpn ipsec site-to-site peer CISCO connection-type 'initiate' set vpn ipsec site-to-site peer CISCO default-esp-group 'ESP-GROUP' set vpn ipsec site-to-site peer CISCO ike-group 'IKE-GROUP' set vpn ipsec site-to-site peer CISCO local-address '10.0.1.2' set vpn ipsec site-to-site peer CISCO remote-address '10.0.2.2' set vpn ipsec site-to-site peer CISCO vti bind 'vti1' Cisco ----- .. code-block:: none crypto isakmp policy 10 encr aes authentication pre-share group 14 lifetime 28800 crypto isakmp key test address 10.0.1.2 ! ! crypto ipsec transform-set TS esp-aes 256 esp-sha256-hmac mode transport ! crypto ipsec profile IPsec-profile set transform-set TS ! ! ! ! ! ! ! interface Loopback0 ip address 1.1.1.1 255.255.255.255 ! interface Tunnel10 ip address 10.100.100.2 255.255.255.252 ip ospf network point-to-point tunnel source GigabitEthernet0/0 tunnel mode ipsec ipv4 tunnel destination 10.0.1.2 tunnel protection ipsec profile IPsec-profile ! interface GigabitEthernet0/0 ip address 10.0.2.2 255.255.255.252 duplex auto speed auto media-type rj45 ! interface GigabitEthernet0/1 ip address 192.168.10.1 255.255.255.0 duplex auto speed auto media-type rj45 ! interface GigabitEthernet0/2 ip address 192.168.11.1 255.255.255.0 duplex auto speed auto media-type rj45 ! router ospf 1 router-id 1.1.1.1 passive-interface GigabitEthernet0/1 passive-interface GigabitEthernet0/2 network 10.100.100.0 0.0.0.3 area 0 network 192.168.10.0 0.0.0.255 area 0 network 192.168.11.0 0.0.0.255 area 0 ! ip route 0.0.0.0 0.0.0.0 10.0.2.1 Monitoring ========== Monitoring on VyOS side ----------------------- IKE SAs: .. code-block:: none vyos@vyos:~$ show vpn ike sa Peer ID / IP Local ID / IP ------------ ------------- 10.0.2.2 10.0.2.2 10.0.1.2 10.0.1.2 State IKEVer Encrypt Hash D-H Group NAT-T A-Time L-Time ----- ------ ------- ---- --------- ----- ------ ------ up IKEv1 AES_CBC_128 HMAC_SHA1_96 MODP_2048 no 8175 18439 IPsec SAs: .. code-block:: none vyos@vyos:~$ show vpn ipsec sa Connection State Uptime Bytes In/Out Packets In/Out Remote address Remote ID Proposal ------------ ------- -------- -------------- ---------------- ---------------- ----------- ----------------------------- CISCO-vti up 34m59s 17K/14K 224/213 10.0.2.2 10.0.2.2 AES_CBC_256/HMAC_SHA2_256_128 OSPF Neighbor Status: .. code-block:: none vyos@vyos:~$ show ip ospf neighbor Neighbor ID Pri State Up Time Dead Time Address Interface RXmtL RqstL DBsmL 1.1.1.1 1 Full/- 1h29m37s 39.317s 10.100.100.2 vti1:10.100.100.1 0 0 0 Routing Table: .. code-block:: none vyos@vyos:~$ show ip route Codes: K - kernel route, C - connected, L - local, S - static, R - RIP, O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP, T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR, f - OpenFabric, t - Table-Direct, > - selected route, * - FIB route, q - queued, r - rejected, b - backup t - trapped, o - offload failure S>* 0.0.0.0/0 [1/0] via 10.0.1.1, eth0, weight 1, 00:07:54 C>* 10.0.1.0/30 is directly connected, eth0, weight 1, 00:07:59 L>* 10.0.1.2/32 is directly connected, eth0, weight 1, 00:07:59 O 10.100.100.0/30 [110/1] is directly connected, vti1, weight 1, 00:07:50 C>* 10.100.100.0/30 is directly connected, vti1, weight 1, 00:07:50 L>* 10.100.100.1/32 is directly connected, vti1, weight 1, 00:07:50 O 192.168.0.0/24 [110/1] is directly connected, eth1, weight 1, 00:07:54 C>* 192.168.0.0/24 is directly connected, eth1, weight 1, 00:07:59 L>* 192.168.0.1/32 is directly connected, eth1, weight 1, 00:07:59 O 192.168.1.0/24 [110/1] is directly connected, eth2, weight 1, 00:07:54 C>* 192.168.1.0/24 is directly connected, eth2, weight 1, 00:07:59 L>* 192.168.1.1/32 is directly connected, eth2, weight 1, 00:07:59 O>* 192.168.10.0/24 [110/2] via 10.100.100.2, vti1, weight 1, 00:07:34 O>* 192.168.11.0/24 [110/2] via 10.100.100.2, vti1, weight 1, 00:07:34 Monitoring on Cisco side ------------------------ IKE SAs: .. code-block:: none Cisco#show crypto isakmp sa IPv4 Crypto ISAKMP SA dst src state conn-id status 10.0.1.2 10.0.2.2 QM_IDLE 1002 ACTIVE IPv6 Crypto ISAKMP SA IPsec SAs: .. code-block:: none Cisco#show crypto ipsec sa interface: Tunnel10 Crypto map tag: Tunnel10-head-0, local addr 10.0.2.2 protected vrf: (none) local ident (addr/mask/prot/port): (0.0.0.0/0.0.0.0/0/0) remote ident (addr/mask/prot/port): (0.0.0.0/0.0.0.0/0/0) current_peer 10.0.1.2 port 500 PERMIT, flags={origin_is_acl,} #pkts encaps: 1295, #pkts encrypt: 1295, #pkts digest: 1295 #pkts decaps: 1238, #pkts decrypt: 1238, #pkts verify: 1238 #pkts compressed: 0, #pkts decompressed: 0 #pkts not compressed: 0, #pkts compr. failed: 0 #pkts not decompressed: 0, #pkts decompress failed: 0 #send errors 0, #recv errors 0 local crypto endpt.: 10.0.2.2, remote crypto endpt.: 10.0.1.2 plaintext mtu 1438, path mtu 1500, ip mtu 1500, ip mtu idb GigabitEthernet0/0 current outbound spi: 0xC3E9B307(3286872839) PFS (Y/N): N, DH group: none inbound esp sas: spi: 0x2740C328(658555688) transform: esp-256-aes esp-sha256-hmac , in use settings ={Tunnel, } conn id: 7, flow_id: SW:7, sibling_flags 80000040, crypto map: Tunnel10-head-0 sa timing: remaining key lifetime (k/sec): (4173824/1401) IV size: 16 bytes replay detection support: Y Status: ACTIVE(ACTIVE) inbound ah sas: inbound pcp sas: outbound esp sas: spi: 0xC3E9B307(3286872839) transform: esp-256-aes esp-sha256-hmac , in use settings ={Tunnel, } conn id: 8, flow_id: SW:8, sibling_flags 80000040, crypto map: Tunnel10-head-0 sa timing: remaining key lifetime (k/sec): (4173819/1401) IV size: 16 bytes replay detection support: Y Status: ACTIVE(ACTIVE) outbound ah sas: outbound pcp sas: OSPF Neighbor Status: .. code-block:: none Cisco# show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 2.2.2.2 0 FULL/ - 00:00:35 10.100.100.1 Tunnel10 Routing Table: .. code-block:: none Cisco#show 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 a - application route + - replicated route, % - next hop override, p - overrides from PfR Gateway of last resort is 10.0.2.1 to network 0.0.0.0 S* 0.0.0.0/0 [1/0] via 10.0.2.1 1.0.0.0/32 is subnetted, 1 subnets C 1.1.1.1 is directly connected, Loopback0 10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks C 10.0.2.0/30 is directly connected, GigabitEthernet0/0 L 10.0.2.2/32 is directly connected, GigabitEthernet0/0 C 10.100.100.0/30 is directly connected, Tunnel10 L 10.100.100.2/32 is directly connected, Tunnel10 O 192.168.0.0/24 [110/1001] via 10.100.100.1, 00:09:36, Tunnel10 O 192.168.1.0/24 [110/1001] via 10.100.100.1, 00:09:36, Tunnel10 192.168.10.0/24 is variably subnetted, 2 subnets, 2 masks C 192.168.10.0/24 is directly connected, GigabitEthernet0/1 L 192.168.10.1/32 is directly connected, GigabitEthernet0/1 192.168.11.0/24 is variably subnetted, 2 subnets, 2 masks C 192.168.11.0/24 is directly connected, GigabitEthernet0/2 L 192.168.11.1/32 is directly connected, GigabitEthernet0/2 Checking Connectivity --------------------- ICMP packets from PC1 to PC3. .. code-block:: none PC1> ping 192.168.10.2 84 bytes from 192.168.10.2 icmp_seq=1 ttl=62 time=8.479 ms 84 bytes from 192.168.10.2 icmp_seq=2 ttl=62 time=3.344 ms 84 bytes from 192.168.10.2 icmp_seq=3 ttl=62 time=3.139 ms 84 bytes from 192.168.10.2 icmp_seq=4 ttl=62 time=3.176 ms 84 bytes from 192.168.10.2 icmp_seq=5 ttl=62 time=3.978 ms ICMP packets from PC2 to PC4. .. code-block:: none PC2> ping 192.168.11.2 84 bytes from 192.168.11.2 icmp_seq=1 ttl=62 time=9.687 ms 84 bytes from 192.168.11.2 icmp_seq=2 ttl=62 time=3.286 ms 84 bytes from 192.168.11.2 icmp_seq=3 ttl=62 time=2.972 ms