SSL authentication

I am trying to configure ssl to encrypt mongo connections.

I have a valid certificate in pfx format. From that I extracted the certificate and key using below commands:-

openssl pkcs12 -in abc.pfx -nocerts -out key.pem -nodes

openssl pkcs12 -in abc.pfx -nokeys -out cert.pem

cat key.pem cert.pem > final.pem

Then used it to start the mongodb process 

./mongod --dbpath /tmp/data/db --sslMode requireSSL --sslPEMKeyFile /tmp/final.pem --port 11232 --sslCAFile /tmp/cert.pem

Then I tried to login from mongo shell with the following command:-

./mongo  --ssl  --port 11232  --sslPEMKeyFile /tmp/final.pem 

But it is giving error 

2014-12-04T09:30:57.213+0530 DBClientCursor::init call() failed

2014-12-04T09:30:57.213+0530 Error: DBClientBase::findN: transport error: vikas.cardtronicsdata.com:11232 ns: admin.$cmd query: { whatsmyuri: 1 } at src/mongo/shell/mongo.js:148

exception: connect failed

And in mongod logs below error is coming:-

connection accepted from 10.10.29.3:36762 #1 (1 connection now open)

2014-12-04T11:44:27.161+0530 [conn1] ERROR: SSL peer certificate validation failed:unable to verify the first certificate

How can I solve this error?