Lets Encrypt HTTP Validation
And the Palo Alto Firewall

The Story

This…… this one…. this one drove me NUTS! for almost a week…. it was a lil mix of a perfect storm I guess… but lets start from the beginning shall we..

So a couple weeks ago i wanted to get active sync setup for my exchange server (Checking OWA sucks)… so I was sought after OPNsense for my open source firewall of choice.

I started following this German blog post, and I hope to have that blog post up very soon as well (sorry I don’t usually get hung up like this).

My setup was pretty much exactly the same however I was getting hung up on the plugin not validating my scripts over HTTP. See the full pain details here on github, anyway, I did finally manage to get my OPNsense server behind the NAT rule to finally succeeded behind my Palo Alto Firewall (by basically opening up the rule way more then I ever wanted to) so I knew! I knew it was the Palo Alto blocking still somehow… but how I couldn’t make sense so I wasn’t sure how to create my Security rule.

First try

My first try was exactly like the github issue describes, was failing on domain key creation, this failed even on my OPNsense with a Public IP and all rules exactly as the OPNsense basic guide states to set it up.

When Neilpang (the main script writer/contributor) said ti was fixed and no commit was applied, I tried again and it worked, I can only assume this was due to the fact DNS may not have replicated to the external DNS servers lets encrypt servers are configured to use when I first made my attempts at a cert validation.

That didnt’ explain why every attempt behind my Palo Alto with a NAT and security rule would fail…

The Palo Alto

I love these things, but they can also be very finicky. to verify my rule I had used my IIS Core VM (That I’ve used in previous posts on how to manage Windows Server Core) along with the HAProxy plugin on OPNsense to basically move the requests from the NAT rule of the Palo Alto but really serve up the IIS website of my IIS server. Not to my amazement, but sure enough I was able to access the IIS website from the internet, so my security rules and nat rules on the Palo ALto are working fine, as well as the security rules on the OPNsense server…. so what gives? Why are these HTTP Validation requests failing??

Again, as stated above I knew it was the Palo Alto from opening up the rule completely and it working, but I figured it was the issue even before I did that… but opening up the security rule completely is not the answer here… like it works but its far to insecure…

So I managed to talk to a friend of mine who happens to be realllllly good at deploying Palo Alto as he does it for a living. I basically describe my issue to him, and ask him if there’s anything he can think of that might be a problem. (I’ll hopefully be having a couple more Palo Alto blog posts as soon as I can get my proper licensed VM) To my actual amazement he goes on about this one setting you can use inside security rules and about a story about when it caused him grief…. go figure, he’s experienced it all!

What was it?!?!?!

Alright so here’s my rule I intially had, which was causing failures of the let’s encrypt OPNsense plugin…

AS you can see nothing really special, until he told me about… PAN DSRI or Palo Alto’s Disable Server Response Inspection you can check the link for more details. Now the funny part is that post covers better performance…. in my case, it was simply needed to work! And all it was, was a checkbox….

once that checkbox was selected, the rule adds a icon to it.

I was able to click Issue certificates on the OPNsense Lets Encrypt plugin, and I got some certs! I’m ready to now add the Let’s Encrypt HAProxy plugin integration and set these certificates for backend services… like my ActiveSync… or OWA… Ohhh exciting stuff!

Man that feels good to finally have that sorted! Wooooo!

November 18, 2018May 4, 2021

Palo Alto VPN (GlobalProtect)
Part 5 – Rules, Testing, Troubleshooting

Intro

In this 5 Part series I covered all the requirements to configure Palo Alto Network’s GlobalProtect VPN:

1) Authentication, Auth Profiles and testing them.

2) Certificates, Cert Profiles, SSL/TLS Profiles and creating them.

3) Portals, what they do and how to configure them.

4) Gateways, what they do and how to configure them.

This part will cover the security rule required, and a little troubleshooting steps along the way.

Things not Covered

I didn’t cover creating DNS records, as again, these come down to your own DNS provider and whatever tools and portals they offer to manage those.

I don’t cover configuring the interfaces (public facing or internal), I don’t cover the virtual router and routes. All these are assumed to be handled by the administrator reading these guides.

I don’t cover installing the client software, if you have the certificates installed on the client devices (Required), it’s simply navigating to the portal address with a supported browser and downloading the installation packages (.exe for windows).

For giggles, I tested navigating my portal from my phone, it did prompt me for my certificate (the VPN was working well) yet after selecting my certificate I got a connection reset error on my browser and checking the Palo Alto Firewall logs (Monitor tab -> traffic) I indeed saw the Deny traffic and action reset-both action… why this is, even though the application was identified correctly as web-browsing and that was enabled in the rule, it wasn’t being allowed by my rule and instead was being denied by my deny all rule. I”m not sure exactly why this is, however I don’t have intentions of accessing my portal web page anytime soon, so for now I’ll ignore this as I use IPsec XAuth RSA on my android device.

I have also noticed that for some reason with Samsung Android I can’t seem to get this VPN setup to work, from quick google searches people seem to say it’s due to packet fragmentation somehow. I haven’t yet had the chance to look into the nitty gritty of this issue just yet, but when I do it will be it’s own blog post!

I also don’t cover installing the completed certificates onto end devices as again this comes down to the end devices being supported by the administrator configuring Global Protect and is outside the scope of this guide.

The Security Rule

As you can tell pretty simple, anyone from the internet (I could be connecting from anywhere, and my IP address changes on my phone all the time, random access points etc) to my public IP address which hosts my portal and gateway, and the required applications (IKE, ipsec-esp-udp, and the SSL and web-browsing) again I haven’t exactly figured out the portal web-page loading issue just yet.

*UPDATE* ensure to add panos-global-protect application type, else only X-auth RSA connection will succeeded, that does not rely on the Global Protect Portals.

Failure to add panos-global-protect applicatin results in end client getting “No Network Available” error on the Global Protect App.

My Phone Config

In my case I do run an Android phone, running : 8.0.0: Kernel 4.4.78

The OS is some H93320g couldn’t find much but this about it…

For the most part I install both my Offline-Root-CA and my Sub-CA certificates on my phone. Which can be found under (General -> Lock Screen & Security -> Encryption & Credentials -> Trusted Credentials (Instead of CA’s who knows?) -> User (Both Should be listed here)

Then Installed the User certificate with the private key, which then shows up under (General -> Lock Screen & Security -> Encryption & Credentials -> User Credentials (Instead of User Certificates?)) The other annoying part is once you have the certificate installed, this area doesn’t allow you to see the certificate details, you can see them under the area mentioned above, but this area…. nope.. :@

Once the certificates are installed, it simply comes down to configuring the VPN settings. (Settings -> Network -> VPN -> BasicVPN -> Click the plus in the upper right hand corner. Then)

Name: Give it a meaningful name

Type: IPSec XAuth RSA

Server Address: The Address defined in Part 3 -> Agents -> External Gateways

IPSec User Cert: The User Certificate you installed and verified above

IPSec CA Certificate: Don’t verify server (Which is probably why I didn’t need the above server address in the gateway certs as a SAN)

IPSec Server Certificate: Receive from server

Then enter a username and password for a user you defined to be allowed per your Authentication Profile you created in Part 1.

You shouldn’t have to define the advanced settings as those should defined to the client from the gateway config we created in Part 4.

Summary

If done correctly you should have a successfully, you should be able to see all the parts play out in both the traffic logs, and the system logs…

System:

Traffic:

That is pretty much it, if you have a failed connection do the usual step by step troubleshooting starting with connectivity, you should be able to see the access attempt from the device in the traffic logs, if they are being blocked by rules, adjust them accordingly.

If you verified all other things, it maybe your chain, or you are enabling extra security like verifying the server certificate than you chain would have to be different then presented here, probably all certificate including the portal and gateway certs being signed by the sub CA completely, then all certs will be trusted by all devices. I’ll admit this isn’t the cleanest setup, but it’s the closest to a bare minimum install of Global Protect using your own internal PKI.

I hope this guide helps someone. 😀

November 18, 2018November 18, 2018

Palo Alto VPN (GlobalProtect)
Part 4 – Gateways

Intro

The Gateway is pretty much exactly as it is named, the gateway where you get a virtual connection to tunnel into the network.

Requirements:

1) And Interface with a Public IP address.
2) Certificates (Covered in Part 2)
3) Authentication Profile (Covered in Part 1)

Configuration

On the Palo Alto Firewall go to Network -> GlobalProtect -> Gateway

Under General give it a Name and define the interface in which has your Public IP address. *Note* The IP address can be left as none, this will work fine if your interface gets its IP address via DHCP, if you have static the static IP address should be populated from the drop down and can be selected. The Appearance section allows you to alter the web login portal that can be used to download the GlobalProtect client software.

Under Authentication Select a SSL/TLS Profile which contains the certificate which will secure this portal)

Then click add under Client Authentication and add the Auth Profile which states which users are going to be allowed to authenticate through this portal. Then select a Certificate Profile. (Covered in Part 2)

This is the first section that actually looks different than the portal configurations, under the Agent section the first area is the tunnel settings. This is where you define which tunnel interface (i picked the default, you may need to create additional tunnel interfaces if doing multiple portal/gateway configurations). In my case I was setting up tunnel based IPsec type VPN.

I left all the Timeout Settings as default, then moved onto client settings. Here we define any particular users, what OS they are allowed, and what IP addresses they are to be assigned (basically acts as a dedicated DHCP for the virtual tunnel interface when the VPN is established).

Next, under Network Services define the internal DNS server and WINS servers, as well as the DNS suffix users who connect will use, this will allow them to work as if they were locally at work.

In my case I didn’t have to deal with HIP Notifications or the Satellites section. 😀

That’s it for the Gateway, this unfortunately is not enough and we still need to define our Security Rules. Luckily since the Portal utilizes a public facing interfaces, we don’t have to deal with any NAT rules as connections are routed through the virtual tunnels that get created pretty much through the settings we defined in this part. 😀

As you can tell these post are a lot shorter as the hardest parts is building the pre-requisites.

Till Part 5, Cheers!

November 17, 2018November 17, 2018

Palo Alto VPN (GlobalProtect)
Part 3 – Portals

Intro

The Portal is pretty much exactly as it is named, the portal where you fist connect to, validate you have the certificate to establish a secure communication to send your credentials over and tell your device what gateway to establish to tunnel connection with.

Requirements:

1) And Interface with a Public IP address.
2) Certificates (Covered in Part 2)
3) Authentication Profile (Covered in Part 1)

Configuration

On the Palo Alto Firewall go to Network -> GlobalProtect -> Portals

Under Authentication Select a SSL/TLS Profile which contains the certificate which will secure this portal)

Then click add under Client Authentication and add the Auth Profile which states which users are going to be allowed to authenticate through this portal.

Under the Agent section is where you define the which users group use which gateways. As well as which CA they use. *NOTE* The address defined as the gateway should created on your external DNS provider. Also it seem it is not required as a SAN on the certificate.

In my case I didn’t have to deal with Satellites section. 😀

That’s it for the Portal, this unfortunately is not enough and we still need to define our gateway as well, which ironically in a simple setup such as in my case and examples as a lot of the same steps.

As you can tell these post are a lot shorter as the hardest parts is building the pre-requisites. I also don’t cover creating your external DNS records as that comes down to your own DNS provider and the tools and services they provide.

Till Part 4, Cheers!