Identifies servers running various SSL VPNs. (They should really be called "TLS-based" VPNs, but "SSL VPN" has become the de facto standard jargon.) Currently it can recognize…

• Cisco AnyConnect and OpenConnect (ocserv)
• Juniper Network Connect/Pulse
• PAN GlobalProtect
• Barracuda Networks
• Check Point
• Microsoft SSTP
• OpenVPN
• Fortinet
• Array Networks
• F5 BigIP
• SonicWall NX (spin-off from Dell)
• Aruba VIA
• Huawei
• H3C

Requires Python 3, pip, and requests:

$ pip3 install https://github.com/dlenski/what-vpn/archive/master.zip
...
$ what-vpn
usage: what-vpn [-h] [-k] [-t SEC] [-v | -c] server [server ...]
what-vpn: error: the following arguments are required: server

$ what-vpn vpn.colorado.edu vpn.northeastern.edu \
    vpn.tnstate.edu vpn.smith.edu vpn.caltech.edu \
    vpn.yale.edu vpn.drew.edu vpn.uca.edu vpn.simmons.edu \
    vpn.nl.edu cpvpn.its.hawaii.edu ssl-vpn.***.com \
    viavpn.luther.edu
vpn.colorado.edu: AnyConnect/OpenConnect (Cisco)
vpn.northeastern.edu: PAN GlobalProtect (portal)
vpn.tnstate.edu: PAN GlobalProtect (portal+gateway)
vpn.smith.edu: Juniper Network Connect
vpn.caltech.edu: AnyConnect/OpenConnect (Cisco, ASA (9.1(6)6))
vpn.yale.edu: AnyConnect/OpenConnect (Cisco, ASA (8.4(5)))
vpn.uca.edu: Barracuda (2017)
vpn.simmons.edu: Check Point (2015, 20%)
vpn.nl.edu: Check Point
cpvpn.its.hawaii.edu: Check Point
vpn.***.com: Array Networks (40%)
ssl-vpn.***.com: no match
viavpn.luther.edu Aruba VIA (80%)

$ what-vpn -kv vpn.***.com

Sniffing ***.***.com ...
  Is it AnyConnect/OpenConnect? ocserv, 0.8.0-0.11.6
  Is it Juniper Network Connect? no match
  Is it PAN GlobalProtect? no match
  Is it Barracuda? no match
  Is it Check Point? no match
  Is it SSTP? no match
  Is it OpenVPN? no match
  => AnyConnect/OpenConnect (ocserv, 0.8.0-0.11.6)

An interesting question for the open source community, including the indispensable OpenConnect (which I also contribute to) is…

What are the most commonly-used SSL VPN protocols in the real world?

In April 2019, I took a list of major universities and companies in the USA, and generated some guesses for the hostnames of their VPN endpoints (e.g. {vpn,ssl-vpn,sslvpn}.*.{edu,com}). I then used what-vpn to probe them all and looked at the subset of the results that matched to an identifiable SSL VPN protocol:

  1  Check Point
  1  Citrix (manually inspected, don't know how to reliably autodetect)
  1  OpenVPN
  5  Dell or SonicWall (manually inspected, didn't know how to reliably autodetect at the time
  7  Fortinet
  7  Barracuda
  8  F5 (manually inspected, didn't know how to reliably autodetect at this time)
 14  SSTP
 53  PAN GlobalProtect (portal and/or gateway)
 72  Juniper Network Connect (or Junos/Pulse, hard to distinguish)
243  Cisco AnyConnect (including 1 ocserv)

Assuming these results are roughly representative of “SSL VPN” deployments in general (at least in the USA), they show that OpenConnect already supports the top 3 most commonly-encountered SSL VPN protocols, or about 80% of SSL VPNs. Additionally Microsoft SSTP is supported by the open-source sstp-client, and of course OpenVPN is well-supported by open-source clients as well.

(Excerpted from this post on the OpenConnect mailing list)

I repeated this analysis in February 2021 (after having implemented F5, SonicWall NX, and Array Networks sniffers, and having improved several others). This time, I expanded the pool of names to include {vpn,ssl-vpn,sslvpn,remote,vpn2,new.vpn,access}.*.{edu,com}. Here are the 2021 results for servers that matched to an identifiable SSL VPN protocol:

  1  Array Networks
  4  Barracuda
  4  Check Point
  6  SonicWall NX
  8  OpenVPN
 14  SSTP
 21  F5 BigIP
 29  Fortinet
 83  Pulse Secure (most also support the older Juniper protocol)
103  PAN GlobalProtect (includes 7 servers that behave in a slightly odd way)
298  Cisco AnyConnect (no ocserv found this time)

We've recently added support in OpenConnect for Fortinet and F5 BigIP (with support for SonicWall NX coming soon). Combined with AnyConnect, GlobalProtect, and Pulse/Juniper, OpenConnect now supports 5 of the most highly-used SSL VPN protocols.

Once again assuming that these results are roughly representative of “SSL VPN” deployments in general (at least in the USA), it appears that OpenConnect now supports almost 93% of SSL VPNs in real-world use.

• Identify non-SSL/TLS-based VPNs? (e.g. IPSEC, à la ike-scan)
• Identify more SSL VPNs: Citrix… any others?
  • Fix apparent false-negatives for some SonicWall/Dell servers
• Identify specific versions or flavors of VPN servers?
• Better confidence levels?

GPLv3 or later