$ curl
https://v2ex.assets.uxengine.net/avatar/3231/749a/68006_normal.png -v
* Trying 23.251.105.133...
* TCP_NODELAY set
* Connected to
v2ex.assets.uxengine.net (23.251.105.133) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* Cipher selection: ALL:!EXPORT:!EXPORT40:!EXPORT56:!aNULL:!LOW:!RC4:@STRENGTH
* successfully set certificate verify locations:
* CAfile: /etc/ssl/certs/ca-certificates.crt
CApath: /etc/ssl/certs
* TLSv1.2 (OUT), TLS header, Certificate Status (22):
* TLSv1.2 (OUT), TLS handshake, Client hello (1):
* TLSv1.2 (IN), TLS handshake, Server hello (2):
* TLSv1.2 (IN), TLS handshake, Certificate (11):
* TLSv1.2 (IN), TLS handshake, Server key exchange (12):
* TLSv1.2 (IN), TLS handshake, Server finished (14):
* TLSv1.2 (OUT), TLS handshake, Client key exchange (16):
* TLSv1.2 (OUT), TLS change cipher, Client hello (1):
* TLSv1.2 (OUT), TLS handshake, Finished (20):
* TLSv1.2 (IN), TLS change cipher, Client hello (1):
* TLSv1.2 (IN), TLS handshake, Finished (20):
* SSL connection using TLSv1.2 / ECDHE-RSA-AES128-GCM-SHA256
* ALPN, server accepted to use h2
* Server certificate:
* subject: CN=
cdn.v2ex.co* start date: Feb 5 18:11:00 2017 GMT
* expire date: May 6 18:11:00 2017 GMT
* subjectAltName: host "
v2ex.assets.uxengine.net" matched cert's "
v2ex.assets.uxengine.net"
* issuer: C=US; O=Let's Encrypt; CN=Let's Encrypt Authority X3
* SSL certificate verify ok.
* Using HTTP2, server supports multi-use
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* Using Stream ID: 1 (easy handle 0x5637264abd60)
> GET /avatar/3231/749a/68006_normal.png HTTP/1.1
> Host:
v2ex.assets.uxengine.net> User-Agent: curl/7.52.1
> Accept: */*
>
* Connection state changed (MAX_CONCURRENT_STREAMS updated)!
< HTTP/2 502
< server: nginx/1.11.3
< date: Mon, 20 Feb 2017 06:47:12 GMT
< content-type: text/html
< content-length: 173
<
<html>
<head><title>502 Bad Gateway</title></head>
<body bgcolor="white">
<center><h1>502 Bad Gateway</h1></center>
<hr><center>nginx/1.11.3</center>
</body>
</html>
* Curl_http_done: called premature == 0
* Connection #0 to host
v2ex.assets.uxengine.net left intact