IPSec on F5-Cisco

I am absolutely agree with the security concerns of using a Wildcard VS and listening on all ports, but it is F5 who published it officially in their deployment guide: https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip-tmos-tunnels-ipsec-13-1-0/10.htmlguid-4a5c2cee-039b-489f-9d78-3e0708491c67

 

Is there any light guide of how to do it with specific VSs, listening on specific IP Addresses, what port or range of ports will be needed? where to configure those VSs [frontend, backend]?

 

Getting a solution working with a wide open Virtual Server is a reasonable plan as a first step in working on the configuration, but after implementation is shown to work, the Virtual Server could be locked down to match traffic-selectors as tightly as possible. Outside of matching the inner (private) IPsec traffic, a wildcard Virtual Server may be handling completely unexpected types of traffic, unrelated to the IPsec traffic.

 

Here's a config example of configuring two BIG-IPs, each with two Virtual Servers for one specific tunnel. Assume the tunnel is between 10.20.131.0/24 <-> 10.10.131.0/24.

 

bigip1

 

tmsh create ltm virtual ipsec-131-encap { destination 10.20.131.0:any ip-forward mask 255.255.255.0 source 10.10.131.0/24 profiles add { fastL4 { } } vlans add { vlan_internal } vlans-enabled }

 

bigip2

 

tmsh create ltm virtual ipsec-131-decap { destination 10.20.131.0:any ip-forward mask 255.255.255.0 source 10.10.131.0/24 profiles add { fastL4 { } } vlans add { vlan_external } vlans-enabled }

 

At this point note, if a flow was initiated by the host on bigip2 to the host on bigip1, the connection would not work. On bigip2, the flow will not match any existing connection and there is no Virtual Server listening to this traffic 10.20.131.1 -> 10.10.131.1. So it is necessary to make a second Virtual Server on both BIG-IP devices to facilitate two-way traffic initiation.

 

bigip1

 

tmsh create ltm virtual ipsec-131-decap { destination 10.10.131.0:any ip-forward mask 255.255.255.0 source 10.20.131.0/24 profiles add { fastL4 { } } vlans add { vlan_external } vlans-enabled } bigip2: Add encapsulating-side side Virtual Server

 

bigip2

 

tmsh create ltm virtual ipsec-131-encap { destination 10.10.131.0:any ip-forward mask 255.255.255.0 source 10.20.131.0/24 profiles add { fastL4 { } } vlans add { vlan1555 } vlans-enabled }

 

One final note, not all types of virtual servers and not all types of profiles will work for IPsec traffic. Stick with the ip-forward.

 

On "IPsec traffic selector", I have three local Networks like:

 

10.15.93.0/24, 10.15.60.0/24 and 10.15.87.0/24 on the "Source IP Address or CIDR" but just one on the "Destination IP Address or CIDR"

 

That means three traffic selectors or can I combine all the source IP Addresses in one line and one traffic selector?

 

The default value for Order setting is "Last" on the F5, but "First" on the F5 deployment guide, How to marry them up?