Hey guys , 

 i have a doubt on how to create an secure connection between o365 and on-premises exchange 2013 server, i.e mails within my domain xyz.com (on cloud) to xyz.com (on prem) should be sent from o365 directly to my on prem exchange without opening port 25 on firewall.

pls help guys. I am new to

How do expect to receive mail if port 25 isn't open on the firewall? 

Note there is also an option of Express Route which should be avail for O365 soon.

You can inquire about it and pricing here:

http://azure.microsoft.com/en-us/services/expressroute/

Hi,

If you want to secure connection between Office 365 with On-premises 2013, check your on-premises email server has Transport Layer Security (TLS) enabled, with a valid certification authority-signed (CA-signed) certificate. Also, configure certificate for the connector.

However, we need port 25 open to confirm the connection between Office 365 and On-premises. More details about it, please refer to: https://technet.microsoft.com/en-us/library/dn751020(v=exchg.150).aspx#Prereqemailserver