Overview

The Trusted IP Range is a list of trusted network address ranges that your organization trusts for access to Salesforce. Designed for power users and large organizations, you can set up the Lead Liaison network as a trusted network for your Salesforce sync account. This will remove friction from the Salesforce login process saving you time and headaches. Trusted IPs are set per Salesforce.com user and/or user profile. The default connection method to Lead Liaison is a token.

...

204.236.232.43
174.129.0.151
54.196.242.118
54.83.94.89
184.73.200.151
54.198.240.103
54.204.111.193
52.86.169.253
35.174.49.207

Your trusted IP should now be all set!  Your users will no longer be required to use the Security Token when linking their Salesforce account.