path: root/docs/configexamples/ipsec-cisco-route-based.md

---
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.webp
:align: center
:alt: Network Topology Diagram
```

## Prerequirements

**VyOS:**

```{eval-rst}
+---------+----------------+
| WAN IP  |  10.0.1.2/30   |
+---------+----------------+
| LAN1 IP | 192.168.0.1/24 |
+---------+----------------+
| LAN2 IP | 192.168.1.1/24 |
+---------+----------------+
```

**Cisco:**

```{eval-rst}
+---------+-----------------+
| WAN IP  | 10.0.2.2/30     |
+---------+-----------------+
| LAN1 IP | 192.168.10.1/24 |
+---------+-----------------+
| LAN2 IP | 192.168.11.1/24 |
+---------+-----------------+
```

**IKE parameters:**

```{eval-rst}
+-------------------+---------+
| Encryption        | AES-128 |
+-------------------+---------+
| HASH              | SHA-1   |
+-------------------+---------+
| Diff-Helman Group | 14      |
+-------------------+---------+
| Life-Time         | 28800   |
+-------------------+---------+
| IKE Version       | 1       |
+-------------------+---------+
```

**IPsec parameters:**

```{eval-rst}
+------------+---------+
| Encryption | AES-256 |
+------------+---------+
| HASH       | SHA-256 |
+------------+---------+
| Life-Time  | 3600    |
+------------+---------+
| PFS        | disable |
+------------+---------+
```

**Hosts configuration**

```{eval-rst}
+--------+--------------+
| 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

```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

```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:

```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:

```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:

```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:

```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:

```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:

```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:

```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:

```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.

```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.

```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
```