Multi-session connection across a trust boundary is described. In an embodiment, a trust boundary can be implemented to restrict access to resources in a secure region from an unsecure region. A connection can be established that is configured as a client-server connection from the secure region to the unsecure region across the trust boundary. A communication engine in the secure region can then control and maintain the established connection as a two-way simultaneous communication link to the unsecure region across the trust boundary such that session messages can be initiated for communication via the two-way simultaneous communication link from either of the secure region or the unsecure region.