download untrusted certifcate in Chrome (Mac)

Question

I have this website which contains an untrusted certificate (self signed). Now I want to download this certificate. But, for example, in Chrome, you only can 'Proceed' or go back (no download option). I'm on a Mac, so I've checked the Keychain access tool but it contains a lot. First of all I don't know if the cert is supposed to be in here, and second, I actually don't know how it looks like. For example, the url is https://example.com:8181/myApp Any suggestions how to find the cert ?

UPDATE: I just noticed that in Chrome you can click on the right of the url on the lock icon. It show some cert info, but still no option to download :(

Answer 1

openssl s_client -connect {HOSTNAME}:{PORT} </dev/null 2>/dev/null|openssl x509 -outform PEM >mycertfile.pem

...explained here.