Interzone Static Routing
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Interzone Static Routing

L1 Bithead

Hi all, I'll preface this as I'm the sole networking guy at my job and I'm still green. Apologies for any dumb questions, I've tried to read the manual for relevant info and used my google-fu to no avail.

 

I'm using a PA-3020 on firmware 8.0.6.

 

I've been asked to integrate a new Cisco ASA for a financial system that allows a tunnel between my site, and their servers to load the webpage client for the software.

I've setup a DMZ for the ASA, and confirmed with the other party that their tunnel is up and able to communicate. So no issues on the DMZ side.

 

I was told to institute static routes to allow hosts to traverse via the ASA over the tunnel. The ASA has two interfaces configured, one for WAN, which is in our DMZ on the IP 10.10.254.1.

The other ASA interface is meant for our internal LAN, and the interface is configured for 10.10.3.253.

 

I'm not 100% sure but I have a feeling my static route is not functioning as intended. Setting a route via windows to the ASA's internal interface (10.10.3.253) will allow me to traverse the tunnel to the needed webpage. Similarly, using another L3 device (velocloud) with static routes set to the ASA's internal IP (10.10.3.253) also allows me traverse the tunnel to the web page.

 

Looking at the CLI, I confirmed the routing table and tested the route and it seems to forward it to ASA's LAN interface at 10.10.3.253. I've checked my firewall security policies, and explicitly allowed traffic on my 10.10.3.0/24 segment to and from the ASA's interface at 10.10.3.253. Is there anything I've missed, or misconfigured?

 

*@PA-3020> show routing fib

--------------------------------------------------------------------------------
virtual-router name: Primary VR
interfaces:
   ethernet1/3 ethernet1/4 ethernet1/5 ethernet1/12
   tunnel tunnel.99 tunnel.100 tunnel.101


route table:
flags: u - up, h - host, g - gateway, e - ecmp, * - preferred path


id      destination           nexthop            flags  interface          mtu
--------------------------------------------------------------------------------
91      0.0.0.0/0             72.*.182.1         ug     ethernet1/3        1500
7       10.10.1.0/24          0.0.0.0            u      tunnel.99          1500
71      10.10.2.0/24          0.0.0.0            u      tunnel.101         1500
30      10.10.3.0/24          0.0.0.0            u      ethernet1/4        1500
29      10.10.3.111/32        0.0.0.0            uh     ethernet1/4        1500
135     10.10.254.0/24        0.0.0.0            u      ethernet1/5        1500
134     10.10.254.254/32      0.0.0.0            uh     ethernet1/5        1500
12      10.99.99.0/24         10.99.99.0         ug     tunnel             1500
76      40.*.92.104/29        0.0.0.0            u      ethernet1/12       1500
75      40.*.92.106/32        0.0.0.0            uh     ethernet1/12       1500
88      72.*.182.0/29         0.0.0.0            u      ethernet1/3        1500
87      72.*.182.2/32         0.0.0.0            uh     ethernet1/3        1500
147     207.*.128.0/21        10.10.3.253        ug     ethernet1/4        1500
148     207.*.139.0/25        10.10.3.253        ug     ethernet1/4        1500
149     208.*.237.43/32       10.10.3.253        ug     ethernet1/4        1500
150     208.*.237.44/32       10.10.3.253        ug     ethernet1/4        1500
--------------------------------------------------------------------------------


*@PA-3020> show routing route

flags: A:active, ?:loose, C:connect, H:host, S:static, ~:internal, R:rip, O:ospf, B:bgp,
       Oi:ospf intra-area, Oo:ospf inter-area, O1:ospf ext-type-1, O2:ospf ext-type-2, E:ecmp, M:multicast


VIRTUAL ROUTER: Primary VR (id 1)
  ==========
destination                                 nexthop                                 metric flags      age   interface          next-AS
0.0.0.0/0                                   40.*.92.105                             200      S              ethernet1/12
0.0.0.0/0                                   72.*.182.1                              10     A S              ethernet1/3
10.10.1.0/24                                0.0.0.0                                 10     A S              tunnel.99
10.10.2.0/24                                0.0.0.0                                 10     A S              tunnel.101
10.10.3.0/24                                10.10.3.111                             0      A C              ethernet1/4
10.10.3.111/32                              0.0.0.0                                 0      A H
10.10.254.0/24                              10.10.254.254                           0      A C              ethernet1/5
10.10.254.254/32                            0.0.0.0                                 0      A H
10.99.99.0/24                               10.99.99.0                              10     A S              tunnel
40.*.92.104/29                              40.*.92.106                             0      A C              ethernet1/12
40.*.92.106/32                              0.0.0.0                                 0      A H
72.*.182.0/29                               72.*.182.2                              0      A C              ethernet1/3
72.*.182.2/32                               0.0.0.0                                 0      A H
207.*.128.0/21                             10.10.3.253                             1      A S              ethernet1/4
207.*.139.0/25                             10.10.3.253                             1      A S              ethernet1/4
208.*.237.43/32                             10.10.3.253                             1      A S              ethernet1/4
208.*.237.44/32                             10.10.3.253                             1      A S              ethernet1/4
total routes shown: 17

*@PA-3020> test routing fib-lookup virtual-router "Primary VR" ip 208.*.237.44

--------------------------------------------------------------------------------
runtime route lookup
--------------------------------------------------------------------------------
virtual-router:   Primary VR
destination:      208.*.237.44
result:
  via 10.10.3.253 interface ethernet1/4, source 10.10.3.111, metric 1
--------------------------------------------------------------------------------

*@PA-3020> test security-policy-match from "LAN Zone" to "LAN Zone" source 10.10.3.24 destination 10.10.3.253 destination-port 443 application web-browsing protocol 6

"*-1; index: 14" {
        from "LAN Zone";
        source any;
        source-region none;
        to "LAN Zone";
        destination 10.10.3.253;
        destination-region none;
        user any;
        category any;
        application/service  any/any/any/any;
        action allow;
        icmp-unreachable: no
        terminal yes;
}

 

Diagram for reference: https://imgur.com/a/dsXoBKJ

 

Thanks

2 REPLIES 2

L4 Transporter

I assume the only way a machine can access resources through the tunnel is with static routes. Firewalls need to see everything in the 3-way handshake or they will drop traffic. In your scenario, the PA will not see the syn-ack since the return traffic bypasses the PA and returns directly to the host.

 

Why use an ASA for a VPN tunnel instead of just using the native capabilities of the PA? It's all standards based PAs connect to many other vendors with no issue.

Why is the inside interface of the ASA on the inside of your network instead of in a DMZ off the PA so it can filter the traffic between you and your partner?

Also, 8.0 code is end of life so you should think about an upgrade.

Hey thanks for replying,

 

I wasn't aware that they'll silently drop traffic without the 3-way.

The ASA is something the vendor insisted on, and would not have it any other way. I don't have a say in it either way.

I'll move the internal interface to it's own network segment and have the PA be the middle man for it all.

 

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