Thursday, December 20, 2018

Azure Point to Site VPN failure with error code 809

I ran into some trouble today troubleshooting a developer's workstation. The issue was when using a Point to Site IKEV2 VPN some clients could not connect - they received an error:

The network connection between your computer and the VPN server could not be established because the remote server is not responding. This could be because one of the network devices (e.g, firewalls, NAT, routers, etc) between your computer and the remote server is not configured to allow VPN connections. Please contact your Administrator or your service provider to determine which device may be causing the problem. (Error 809)
The strange thing was that some other workstations seemed fine.

After bashing our collective heads against the wall, checking checking the P2SChild, doing all sorts of network troubleshooting to the endpoint DNS name -, editing registry, checking firewalls, etc, we finally determined the cause of the issue.

The issue was only apparent on Windows 10 desktops with OS version 1703. After manually updating these Workstations to Windows 10 1803 we no longer received the 809 error.

Moral of the story - Remember to update your Windows 10 versions!

Tuesday, December 18, 2018

Tip 0004: Handy Cheatsheats

Here are some handy cheat-sheets to reference for Powershell, Git, ETC.

Here is a great list of network cheat-sheets.

Wednesday, December 5, 2018

Tip 0003: ASP page to emulate server response codes

This is a handy page to emulate a response code on the server. This is useful for testing your custom error pages, either from IIS or Cloudflare.

<%@ Page Language="C#" AutoEventWireup="true"%>
<script runat="server">
protected override void OnLoad(EventArgs e)
this.Response.StatusCode = 418;
Response.TrySkipIisCustomErrors = true;

TIP 0005: Test bad SSL

This is a tool for testing "memorable site for testing clients against bad SSL configs"