Java SSLException: hostname in certificate didn't match

I have been using the following code to connect to one of google's service. This code worked fine on my local machine :

HttpClient client=new DefaultHttpClient();
HttpPost post = new HttpPost("https://www.google.com/accounts/ClientLogin");
post.setEntity(new UrlEncodedFormEntity(myData));
HttpResponse response = client.execute(post);

I put this code in a production environment, which had blocked Google.com. On request, they allowed communication with Google server by allowing me to accessing an IP : 74.125.236.52 - which is one of Google's IPs. I edited my hosts file to add this entry too.

Still I could not access the URL, which I wonder why. So I replaced the above code with :

HttpPost post = new HttpPost("https://74.125.236.52/accounts/ClientLogin");

Now I get an error like this :

javax.net.ssl.SSLException: hostname in certificate didn't match: <74.125.236.52> != <www.google.com>

I guess this is because Google has multiple IPs. I cant ask the network admin to allow me access to all those IPs - I may not even get this entire list.

What should I do now ? Is there a workaround at Java level ? Or is it totally in hands of the network guy ?

You can also try to set a HostnameVerifier as described here. This worked for me to avoid this error.

// Do not do this in production!!!
HostnameVerifier hostnameVerifier = org.apache.http.conn.ssl.SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER;

DefaultHttpClient client = new DefaultHttpClient();

SchemeRegistry registry = new SchemeRegistry();
SSLSocketFactory socketFactory = SSLSocketFactory.getSocketFactory();
socketFactory.setHostnameVerifier((X509HostnameVerifier) hostnameVerifier);
registry.register(new Scheme("https", socketFactory, 443));
SingleClientConnManager mgr = new SingleClientConnManager(client.getParams(), registry);
DefaultHttpClient httpClient = new DefaultHttpClient(mgr, client.getParams());

// Set verifier     
HttpsURLConnection.setDefaultHostnameVerifier(hostnameVerifier);

// Example send http request
final String url = "https://encrypted.google.com/";  
HttpPost httpPost = new HttpPost(url);
HttpResponse response = httpClient.execute(httpPost);

The certificate verification process will always verify the DNS name of the certificate presented by the server, with the hostname of the server in the URL used by the client.

The following code

HttpPost post = new HttpPost("https://74.125.236.52/accounts/ClientLogin");

will result in the certificate verification process verifying whether the common name of the certificate issued by the server, i.e. www.google.com matches the hostname i.e. 74.125.236.52. Obviously, this is bound to result in failure (you could have verified this by browsing to the URL https://74.125.236.52/accounts/ClientLogin with a browser, and seen the resulting error yourself).

Supposedly, for the sake of security, you are hesitant to write your own TrustManager (and you musn't unless you understand how to write a secure one), you ought to look at establishing DNS records in your datacenter to ensure that all lookups to www.google.com will resolve to 74.125.236.52; this ought to be done either in your local DNS servers or in the hosts file of your OS; you might need to add entries to other domains as well. Needless to say, you will need to ensure that this is consistent with the records returned by your ISP.