purpose of xp extensions

[Matthew Newton]

On Fri, 2018-06-29 at 16:08 +0800, d tbsky wrote:
> Hmmm. I tried to use let's encrypt certificate, and windows 7 seems
> to swallow it.

Let's Encrypt certs include the TLS Web Server Auth EKU, as do all
commercial certs used for web servers.

> BTW, how can we check if the certificate comes with xp extensions or
> not?
> I tried to use "openssl x509 -text -in my.crt", but can not find info
> about the extension.

in

  X509v3 extensions:

look for

    X509v3 Extended Key Usage: 
      TLS Web Server Authentication, TLS Web Client Authentication

-- 
Matthew