[openssl] openssl s_client using a proxy

openssl s_client -connect some.https.server:443 -showcerts

is a nice command to run when you want to inspect the server's certificates and its certificate chain.

Is there a way to run this command when you are behind a HTTP/HTTPS proxy ?

You can use proxytunnel:

proxytunnel -p yourproxy:8080 -d www.google.com:443 -a 7000

and then you can do this:

openssl s_client -connect localhost:7000 -showcerts

Hope this can help you!

since openssl v1.1.0

C:\openssl>openssl version
OpenSSL 1.1.0g  2 Nov 2017
C:\openssl>openssl s_client -proxy 192.168.103.115:3128 -connect www.google.com -CAfile C:\TEMP\internalCA.crt
CONNECTED(00000088)
depth=2 DC = com, DC = xxxx, CN = xxxx CA interne
verify return:1
depth=1 C = FR, L = CROIX, CN = svproxysg1, emailAddress = [email protected]
verify return:1
depth=0 C = US, ST = California, L = Mountain View, O = Google Inc, CN = www.google.com
verify return:1
---
Certificate chain
 0 s:/C=US/ST=California/L=Mountain View/O=Google Inc/CN=www.google.com
   i:/C=xxxx/L=xxxx/CN=svproxysg1/[email protected]
 1 s:/C=xxxx/L=xxxx/CN=svproxysg1/[email protected]
   i:/DC=com/DC=xxxxx/CN=xxxxx CA interne
---
Server certificate
-----BEGIN CERTIFICATE-----
MIIDkTCCAnmgAwIBAgIJAIv4/hQAAAAAMA0GCSqGSIb3DQEBCwUAMFIxCzAJBgNV
BAYTAkZSMQ4wDAYDVQQHEwVDUk9JWDETMBEGA1UEAxMKc3Zwcm94eXNnMTEeMBwG

Even with openssl v1.1.0 I had some problems passing our proxy, e.g. s_client: HTTP CONNECT failed: 400 Bad Request That forced me to write a minimal Java-class to show the SSL-Handshake

    public static void main(String[] args) throws IOException, URISyntaxException {
    HttpHost proxy = new HttpHost("proxy.my.company", 8080);
    DefaultProxyRoutePlanner routePlanner = new DefaultProxyRoutePlanner(proxy);
    CloseableHttpClient httpclient = HttpClients.custom()
            .setRoutePlanner(routePlanner)
            .build();
    URI uri = new URIBuilder()
            .setScheme("https")
            .setHost("www.myhost.com")
            .build();
    HttpGet httpget = new HttpGet(uri);
    httpclient.execute(httpget);
}

With following dependency:

    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.5.2</version>
        <type>jar</type>
    </dependency>

you can run it with Java SSL Logging turned on

This should produce nice output like

trustStore provider is :
init truststore
adding as trusted cert:
  Subject: CN=Equifax Secure Global eBusiness CA-1, O=Equifax Secure Inc., C=US
  Issuer:  CN=Equifax Secure Global eBusiness CA-1, O=Equifax Secure Inc., C=US
  Algorithm: RSA; Serial number: 0xc3517
  Valid from Mon Jun 21 06:00:00 CEST 1999 until Mon Jun 22 06:00:00 CEST 2020

adding as trusted cert:
  Subject: CN=SecureTrust CA, O=SecureTrust Corporation, C=US
  Issuer:  CN=SecureTrust CA, O=SecureTrust Corporation, C=US
(....)

for anyone coming here as of post-May 2015: there's a new "-proxy" option that will be included in the next release of openssl: https://rt.openssl.org/Ticket/Display.html?id=2651&user=guest&pass=guest