OSPF with IPsec VPN to achieve network redundancy

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OSPF with IPsec VPN to achieve network redundancy

This recipe provides sample configuration of using OSPF with IPsec VPN to achieve network redundancy. Route selection is based on OSPF cost calculation. It is easy to achieve ECMP or primary/secondary routes by adjusting OSPF path cost.

The following shows the sample network topology for this recipe:

As only partial configuration can be completed from the GUI, it is recommended to achieve this configuration via the CLI commands as shown below.

To configure OSPF with IPsec VPN to achieve network redundancy using the CLI:

  1. Configure the WAN interface and static route. Each FortiGate has two WAN interfaces connected to different ISPs.

The ISP1 link is for the primary FortiGate and the IPS2 link is for the secondary FortiGate: a. Configure HQ1:

config system interface edit “port1” set alias to_ISP1

set ip 172.16.200.1 255.255.255.0

next edit “port2” set alias to_ISP2

set ip 172.17.200.1 255.255.255.0

next

end

config router static edit 1 set gateway 172.16.200.3 set device “port1”

next edit 2 set gateway 172.17.200.3 set device “port2” set priority 100

next

end

  1. Configure HQ2:

config system interface edit “port25” set alias to_ISP1

set ip 172.16.202.1 255.255.255.0

next edit “port26” set alias to_ISP2

set ip 172.17.202.1 255.255.255.0

next

end

config router static edit 1 set gateway 172.16.202.2

set device “port25”

next edit 2 set gateway 172.17.202.2 set device “port26” set priority 100

next

end

  1. Configure the internal (protected subnet) interface:
    1. Configure HQ1:

config system interface edit “dmz” set ip 10.1.100.1 255.255.255.0

next

end

  1. Configure HQ2:

config system interface edit “port9” set ip 172.16.101.1 255.255.255.0

next

end

  1. Configure IPsec phase1-interface and phase-2 interface. On each FortiGate, configure two IPsec tunnels: a primary and a secondary: Configure HQ1:

config vpn ipsec phase1-interface edit “pri_HQ2” set interface “port1” set peertype any set net-device enable

set proposal aes128-sha256 aes256-sha256 aes128-sha1 aes256-sha1 set remote-gw 172.16.202.1 set psksecret sample1

next edit “sec_HQ2” set interface “port2” set peertype any set net-device enable

set proposal aes128-sha256 aes256-sha256 aes128-sha1 aes256-sha1 set remote-gw 172.17.202.1 set psksecret sample2

next end

config vpn ipsec phase2-interface edit “pri_HQ2” set phase1name “pri_HQ2”

set proposal aes128-sha1 aes256-sha1 aes128-sha256 aes256-sha256 aes128gcm aes256gcm chacha20poly1305

set auto-negotiate enable

next edit “sec_HQ2” set phase1name “sec_HQ2”

set proposal aes128-sha1 aes256-sha1 aes128-sha256 aes256-sha256 aes128gcm aes256gcm chacha20poly1305

set auto-negotiate enable

next end

  1. Configure HQ2:

config vpn ipsec phase1-interface edit “pri_HQ1” set interface “port25” set peertype any set net-device enable

set proposal aes128-sha256 aes256-sha256 aes128-sha1 aes256-sha1 set remote-gw 172.16.200.1 set psksecret sample1

next edit “sec_HQ1” set interface “port26” set peertype any set net-device enable

set proposal aes128-sha256 aes256-sha256 aes128-sha1 aes256-sha1 set remote-gw 172.17.200.1 set psksecret sample2

next

end

config vpn ipsec phase2-interface edit “pri_HQ1” set phase1name “pri_HQ1”

set proposal aes128-sha1 aes256-sha1 aes128-sha256 aes256-sha256 aes128gcm aes256gcm chacha20poly1305

set auto-negotiate enable

next edit “sec_HQ1” set phase1name “sec_HQ1”

set proposal aes128-sha1 aes256-sha1 aes128-sha256 aes256-sha256 aes128gcm aes256gcm chacha20poly1305

set auto-negotiate enable

next

end

  1. Configure an inbound and outbound firewall policy for each IPsec tunnel:
  2. Configure HQ1:

config firewall policy

edit 1 set name “pri_inbound” set srcintf “pri_HQ2” set dstintf “dmz” set srcaddr “172.16.101.0” set dstaddr “10.1.100.0” set action accept set schedule “always” set service “ALL”

next edit 2 set name “pri_outbound” set srcintf “dmz” set dstintf “pri_HQ2” set srcaddr “10.1.100.0” set dstaddr “172.16.101.0” set action accept set schedule “always” set service “ALL” next

edit 3

set name “sec_inbound” set srcintf “sec_HQ2” set dstintf “dmz” set srcaddr “172.16.101.0” set dstaddr “10.1.100.0” set action accept set schedule “always” set service “ALL”

next edit 4

set name “sec_outbound” set srcintf “dmz” set dstintf “sec_HQ2” set srcaddr “10.1.100.0” set dstaddr “172.16.101.0” set action accept set schedule “always” set service “ALL”

next

end

  1. Configure HQ2:

config firewall policy edit 1

set name “pri_inbound” set srcintf “pri_HQ1” set dstintf “port9” set srcaddr “10.1.100.0” set dstaddr “172.16.101.0” set action accept set schedule “always” set service “ALL”

next edit 2

set name “pri_outbound” set srcintf “port9” set dstintf “pri_HQ1” set srcaddr “10.1.100.0” set dstaddr “172.16.101.0” set action accept set schedule “always” set service “ALL”

next edit 3

set name “sec_inbound” set srcintf “sec_HQ1” set dstintf “port9” set srcaddr “10.1.100.0” set dstaddr “172.16.101.0” set action accept set schedule “always” set service “ALL”

next edit 4

set name “sec_outbound” set srcintf “port9” set dstintf “sec_HQ1” set srcaddr “172.16.101.0” set dstaddr “10.1.100.0” set action accept set schedule “always” set service “ALL”

next

end

  1. Assign an IP address to the IPsec tunnel interface:
  2. Configure HQ1:

config system interface

edit “pri_HQ2”

set ip 10.10.10.1 255.255.255.255

set remote-ip 10.10.10.2 255.255.255.255

next edit “sec_HQ2”

set ip 10.10.11.1 255.255.255.255 set remote-ip 10.10.11.2 255.255.255.255

next

end

  1. Configure HQ2:

config system interface

edit “pri_HQ1”

set ip 10.10.10.2 255.255.255.255

set remote-ip 10.10.10.1 255.255.255.255

next

edit “sec_HQ1”

set ip 10.10.11.2 255.255.255.255 set remote-ip 10.10.11.1 255.255.255.255

next

end

  1. Configure OSPF:
  2. Configure HQ1:

config router ospf

set router-id 1.1.1.1 config area

edit 0.0.0.0 next

end config ospf-interface

edit “pri_HQ2” set interface “pri_HQ2” set cost 10 set network-type point-to-point

next edit “sec_HQ2” set interface “sec_HQ2” set cost 20 set network-type point-to-point

next

end config network

edit 1 set prefix 10.10.10.0 255.255.255.0

next edit 2

set prefix 10.10.11.0 255.255.255.0

next edit 3 set prefix 10.1.100.0 255.255.255.0

next

end

end

  1. Configure HQ2:

config router ospf set router-id 2.2.2.2 config area edit 0.0.0.0 next

end

config ospf-interface edit “pri_HQ1” set interface “pri_HQ1”

set cost 10

set network-type point-to-point

next edit “sec_HQ1” set interface “sec_HQ1”

set cost 20

set network-type point-to-point

next

end config network edit 1 set prefix 10.10.10.0 255.255.255.0

next edit 2 set prefix 10.10.11.0 255.255.255.0

next edit 3 set prefix 172.16.101.0 255.255.255.0

next

end

end

  1. Run diagnose/get commands to check VPN and OSPF states:
  2. Run the HQ1 # diagnose vpn ike gateway list command. The system should return the following:

vd: root/0 name: pri_HQ2 version: 1 interface: port1 11 addr: 172.16.200.1:500 -> 172.16.202.1:500 virtual-interface-addr: 10.10.10.1 -> 10.10.10.2 created: 1024s ago

IKE SA: created 1/1 established 1/1 time 0/0/0 ms

IPsec SA: created 1/3 established 1/2 time 0/5/10 ms id/spi: 45 d184777257b4e692/e2432f834aaf5658 direction: responder status:

established 1024-1024s ago = 0ms proposal: aes128-sha256 key: 9ed41fb06c983344189538046f5ad204 lifetime/rekey: 86400/85105 DPD sent/recv: 00000003/00000000 vd: root/0

name: sec_HQ2 version: 1 interface: port2 12 addr: 172.17.200.1:500 -> 172.17.202.1:500 virtual-interface-addr: 10.10.11.1 -> 10.10.11.2 created: 346s ago

IKE SA: created 1/1 established 1/1 time 0/0/0 ms

IPsec SA: created 1/1 established 1/1 time 0/10/15 ms id/spi: 48 d909ed68636b1ea5/163015e73ea050b8 direction: initiator status:

established 0-0s ago = 0ms proposal: aes128-sha256 key: b9e93c156bdf4562-

29db9fbafa256152 lifetime/rekey: 86400/86099 DPD sent/recv: 00000000/00000000

  1. Run the HQ1 # diagnose vpn tunnel list command. The system should return the following:

list all ipsec tunnel in vd 0

name=pri_HQ2 ver=1 serial=1 172.16.200.1:0->172.16.202.1:0

bound_if=11 lgwy=static/1 tun=intf/0 mode=auto/1 encap=none/528 options[0210]=create_ dev frag-rfc accept_traffic=1

proxyid_num=1 child_num=0 refcnt=14 ilast=2 olast=2 ad=/0 stat: rxp=102 txp=105 rxb=14064 txb=7816

dpd: mode=on-demand on=1 idle=20000ms retry=3 count=0 seqno=3 natt: mode=none draft=0 interval=0 remote_port=0 proxyid=pri_HQ2 proto=0 sa=1 ref=2 serial=1 auto-negotiate src: 0:0.0.0.0/0.0.0.0:0 dst: 0:0.0.0.0/0.0.0.0:0 SA: ref=3 options=18227 type=00 soft=0 mtu=1438 expire=42254/0B replaywin=2048

seqno=6a esn=0 replaywin_lastseq=00000067 itn=0

life: type=01 bytes=0/0 timeout=42932/43200 dec: spi=1071b4ee esp=aes key=16

032036b24a4ec88da63896b86f3a01db ah=sha1 key=20 3962933e24c8da21c65c13bc2c6345d643199cdf

enc: spi=ec89b7e3 esp=aes key=16 92b1d85ef91faf695fca05843dd91626 ah=sha1 key=20 2de99d1376506313d9f32df6873902cf6c08e454

dec:pkts/bytes=102/7164, enc:pkts/bytes=105/14936

name=sec_HQ2 ver=1 serial=2 172.17.200.1:0->172.17.202.1:0

bound_if=12 lgwy=static/1 tun=intf/0 mode=auto/1 encap=none/528 options[0210]=create_ dev frag-rfc accept_traffic=1

proxyid_num=1 child_num=0 refcnt=14 ilast=3 olast=0 ad=/0 stat: rxp=110 txp=114 rxb=15152 txb=8428

dpd: mode=on-demand on=1 idle=20000ms retry=3 count=0 seqno=3 natt: mode=none draft=0 interval=0 remote_port=0 proxyid=sec_HQ2 proto=0 sa=1 ref=2 serial=1 auto-negotiate src: 0:0.0.0.0/0.0.0.0:0 dst: 0:0.0.0.0/0.0.0.0:0 SA: ref=3 options=18227 type=00 soft=0 mtu=1438 expire=42927/0B replaywin=2048

seqno=2 esn=0 replaywin_lastseq=00000002 itn=0

life: type=01 bytes=0/0 timeout=42931/43200 dec: spi=1071b4ef esp=aes key=16 bcdcabdb7d1c7c695d1f2e0f5441700a

ah=sha1 key=20 e7a0034589f82eb1af41efd59d0b2565fef8d5da

enc: spi=ec89b7e4 esp=aes key=16 234240b69e61f6bdee2b4cdec0f33bea ah=sha1 key=20 f9d4744a84d91e5ce05f5984737c2a691a3627e8

dec:pkts/bytes=1/68, enc:pkts/bytes=1/136

  1. Run the HQ1 # get router info ospf neighbor The system should return the following:

OSPF process 0, VRF 0:

Neighbor ID Pri State Dead Time Address Interface

2.2.2.2 1. Full/ – 00:00:37 10.10.10.2 pri_HQ2

2.2.2.2 1. Full/ – 00:00:32 10.10.11.2 sec_HQ2

  1. Run the HQ1 # get router info routing-table ospf The system should return the following:

Routing table for VRF=0

O 172.16.101.0/24 [110/20] via 10.10.10.2, pri_HQ2 , 00:03:21 In case the primary tunnel is down after route convergence.

  1. Run the HQ1 # get router info routing-table ospf The system should return the following:

Routing table for VRF=0

O 172.16.101.0/24 [110/110] via 10.10.11.2, sec_HQ2 , 00:00:01

This entry was posted in Administration Guides, FortiGate, FortiOS 6.2 on by .

About Mike

Michael Pruett, CISSP has a wide range of cyber-security and network engineering expertise. The plethora of vendors that resell hardware but have zero engineering knowledge resulting in the wrong hardware or configuration being deployed is a major pet peeve of Michael's. This site was started in an effort to spread information while providing the option of quality consulting services at a much lower price than Fortinet Professional Services. Owns PacketLlama.Com (Fortinet Hardware Sales) and Office Of The CISO, LLC (Cybersecurity consulting firm).

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