Another small post out of my “At a Glance” series: The different types of virtual private networks (VPNs). Looking at Site-to-Site and Remote Access VPNs.
There are two methods of site-to-site VPN tunnels: route-based and policy-based. While some of you may already be familiar with this, some may have never heard of it. Some firewalls only implement one of these types, so you probably don’t have a chance to configure the other one anyway. Too bad since route-based VPNs have many advantages over policy-based ones which I will highlight here.
I had many situations in which network admins did not know the differences between those two methods and simply configured “some kind of” VPN tunnel regardless of any methodology. In this blogpost I am explaining the structural differences between them along with screenshots of common firewalls. I am explaining all advantages of route-based VPNs and listing a table comparing some firewalls regarding their VPN features.
In my previous blogpost I talked about the true random number generator (TRNG) within the Raspberry Pi. Now I am using it for a small online pre-shared key (PSK) generator at https://random.weberlab.de (IPv6-only) that you can use e.g. for site-to-site VPNs. Here are some details how I am reading the binary random data and how I built this small website.
Just a few days ago I gave a talk at Troopers 18 in Heidelberg, Germany, about the problems of dynamic (non-persistent) IPv6 prefixes, as well as IPv6 VPNs in general. Following are my slides and the video of the talk:
It is probably one of the most used protocols in my daily business but I have never captured it in detail: IKE and IPsec/ESP. And since IKEv2 is coming I gave it a try and tcpdumped two VPN session initiations with IKEv1 main mode as well as with IKEv2 to see some basic differences.
Of course I know that all VPN protocols are encrypted – hence you won’t see that much data. But at least you can see the basic message flow such as “only 4 messages with IKEv2” while some more for legacy IKEv1. I won’t go into the protocol details at all. I am merely publishing two pcap files so that anyone can have a look at a VPN session initiation. A few Wireshark screenshots complete the blogpost.
A few month ago I published many Layer 2/3 challenges on my blog. Beside the happy feedback I got some remarks that the challenges were to easy at all because you only needed the display filter at Wireshark while no deep protocol knowledge.
Ok, “challenge excepted” ;) here I have some more protocol related challenges for you: With this post I am publishing a pcap which has four site-to-site IPsec VPN connections inside. On the first half of the pcap all four of them are wrongly configured, hence, not working. –> What are the reasons for that? <–
And one more IPsec VPN post, again between the Palo Alto Networks firewall and a Fortinet FortiGate, again over IPv6 but this time with IKEv2. It was no problem at all to change from IKEv1 to IKEv2 for this already configured VPN connection between the two different firewall vendors. Hence I am only showing the differences within the configuration and some listings from common CLI outputs for both firewalls.
Towards the global IPv6-only strategy ;) VPN tunnels will be used over IPv6, too. I configured a static IPsec site-to-site VPN between a Palo Alto Networks and a Fortinet FortiGate firewall via IPv6 only. I am using it for tunneling both Internet Protocols: IPv6 and legacy IP.
While it was quite easy to bring the tunnel “up”, I had some problems tunneling both Internet Protocols over the single phase 2 session. The reason was some kind of differences within the IPsec tunnel handling between those two firewall vendors. Here are the details along with more than 20 screenshots and some CLI listings.
Just for fun some more VPN throughput tests, this time for the late Juniper ScreenOS firewalls. I did the same iperf TCP tests as in my labs for Fortinet and Palo Alto, while I was using six different phase1/2 proposals = crypto algorithms. The results were as expected with one exception.
Once more some throughput tests, this time the Palo Alto Networks firewalls site-to-site IPsec VPN. Similar to my VPN speedtests for the FortiGate firewall, I set up a small lab with two PA-200 firewalls and tested the bandwidth of different IPsec phase 2 algorithms. Compared to the official data sheet information from Palo Alto that state an IPsec VPN throughput of 50 Mbps, the results are really astonishing.
The most common transition method for IPv6 (that is: how to enable IPv6 on a network that does not have a native IPv6 connection to the Internet) is a “6in4” tunnel. Other tunneling methods such as Teredo or SixXS are found on different literatures as well. However, another method that is not often explained is to tunnel the IPv6 packets through a normal VPN connection. For example, if the main office has a native IPv6 connection to the Internet as well as VPN connections to its remote offices, it is easy to bring IPv6 subnets to these stations. Here comes an example with two Palo Alto firewalls.
Ähnlich zum dem Site-to-Site VPN Throughput Test der FortiGate Firewalls wollte ich mal den FRITZ!Boxen auf den Zahn fühlen und herausfinden, in wie fern sich der VPN-Durchsatz bei den Modellen unterscheidet, bzw. welche Rolle die ausgewählten Verschlüsselungsverfahren spielen. Getestet habe ich eine (etwas ältere) FRITZ!Box 7270v3 mit FRITZ!OS 06.06 sowie eine (neuere, obgleich nicht Topmodell) FRITZ!Box 7430 in Version 06.30. Als VPN-Endpunkt auf der Gegenseite habe ich eine FortiGate Firewall genommen. Getestet wurde das reine Routing/NATting sowie verschiedene Phase 2 Proposals mit dem Netzwerk Tool iperf.
Triggered by a customer who had problems getting enough speed through an IPsec site-to-site VPN tunnel between FortiGate firewalls I decided to test different encryption/hashing algorithms to verify the network throughput. I used two FortiWiFi 90D firewalls that have an official IPsec VPN throughput of 1 Gbps. Using iperf I measured the transfer rates with no VPN tunnel as well as with different IPsec proposals.
I first ran into really slow performances which were related to the default “Software Switch” on the FortiGate. After deleting this type of logical switch, the VPN throughput was almost as expected.
When using a multilayer firewall design it is not directly clear on which of these firewalls remote site-to-site VPNs should terminate. What must be considered in such scenarios? Differentiate between partners and own remote offices? Or between static and dynamic peer IPs? What about the default routes on the remote sites?
Following is a discussion about different approaches and some best practices. Since not all concepts work with all firewall vendors, the following strategies are separated by common firewalls, i.e., Cisco ASA, Fortinet FortiGate, Juniper ScreenOS, Palo Alto.
How to route traffic inside an IPv6 site-to-site VPN tunnel if one side offers only dynamic IPv6 prefixes? With IPv4, the private network segments were statically routed through the tunnel. But with a dynamic prefix, a static route is not possible. That is, a dynamic routing protocol must be used. Here is an example of how I used OSPFv3 for IPv6 between my VPN endpoints.
In detail, I have a home office with a dual stack ISP connection. However, this connection has a dynamic IPv6 prefix: After every reboot or lost connection of the firewall, I get a new IPv6 prefix. This is really bad for building a site-to-site VPN to the headquarter. Since I don’t want to use any kind of NAT/NPTv6 with unique local addresses, I am talking OSPFv3 over the VPN tunnel in order to route the dynamic prefix range (global unicast) via the tunnel.