ssl handshake fail when proxy between two tomcat with mutual authentication

[drinsnow]

Hi, 

I've got a problem when setting up nginx as load balancer between two
tomcats with mutual authentication. 

The system is like: Tomcat1 <--https-> Nginx <--https--> Tomcat2. 

Before adding nginx, the mutual authentication between tomcat1 and tomcat2
works fine, using cert/key and keystore/truststore. Now with nginx, links
between tomcat1 and nginx is OK, but the SSL handshake between nginx and
tomcat2 not work. Wonder how to assign the keystore/truststore stuff that
needed when communicating with tomcat2, can't find related directive in
nginx ssl module configuration. 

Any idea for this? Thanks!

My nginx configuration is like:

    upstream backend {
        server 10.1.1.1:8443;
        server 10.1.1.2:8443;
    }

    server {
        listen       8443 ssl;
        server_name  localhost;
        ssl_certificate             /etc/nginx/ssl/server.crt;
        ssl_certificate_key         /etc/nginx/ssl/server.key;
        ssl_client_certificate      /etc/nginx/ssl/ca.crt;
        ssl_ciphers ALL:!ADH:!kEDH:!SSLv2:!EXPORT40:!EXP:!LOW;
        ssl_verify_client on;
        ssl_verify_depth 2;

        location / {
            proxy_pass https://backend;
        }
    } 

And tomcat2 configuration is like: 
    <Connector port="8443" maxHttpHeaderSize="8192"
               maxThreads="100"
               enableLookups="false" disableUploadTimeout="true"
               acceptCount="100" scheme="https" secure="true"
               SSLEnabled="true"
               SSLCertificateFile="${catalina.base}/conf/ssl/server.crt"
               SSLCertificateKeyFile="${catalina.base}/conf/ssl/server.key"
               SSLCACertificateFile="${catalina.base}/conf/ssl/ca.crt"
               SSLCipherSuite="ALL:!ADH:!kEDH:!SSLv2:!EXPORT40:!EXP:!LOW"
               SSLVerifyClient="require" />

And the error log is: 
2013/07/23 20:25:11 [error] 18116#0: *1 SSL_do_handshake() failed (SSL:
error:14094410:SSL routines:SSL3_READ_BYTES:sslv3 alert handshake
failure:SSL alert number 40) while SSL handshaking to upstream, client ***

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,241171,241171#msg-241171