For security reasons, Salesforce requires each computer, tablet or other device to be identified and authenticated before it can access a specific Salesforce instance. To do this they offer two options:
1) use a verification code that has been emailed to the user;
2) whitelist an IP address or range, which will eliminate the need to use a verification code.
By whitelisting your IP address in Salesforce, you will allow all devices to log into Salesforce from that IP address if the proper username and passwords are used so if you are whitelisting an address for temporary purposes, you should remove it from the list when done.
To whitelist your IP address for a new location, follow the steps below: (Note that you must be a Salesforce system administrator to perform these steps).
1. Go to Setup
2. Go to Security Controls, then Network Access
3. Create a New Trusted IP Range
4. Create a New Trusted IP Range and click Save.