Subway to the Stars - Nathan Dodge

Solar Subway Systems invented a way to stretch a wormhole between two points, allowing near-instantaneous travel not only between any two locations on Earth, but also between the planets and satellites of the solar system. SSS VP of Engineering Charles (Scotty) Hays and Chief Scientist Robert (Bobby) Taylor, along with field service genius Carol (Kaley) Sellers, have built SSS into a major multi-billion-dollar corporation.

Unfortunately, the SSS portal system allowed a relentlessly hostile alien race to "dial in" to the portal system and launch an invasion. The attack was driven off, but the "Bugs" are still doin their best to forge an entry back to Earth. The invaders are now taking over pirate (unauthorized) portals built to take advantage of the solar-system-wide portal network, and have managed to sneak into hidden locations on Earth.

Suddenly humanity's solar system is faced with a Bug invasion already spreading over Earth and also to Mars. Again called into service by the US Intersolar Command, Scotty, Bobby and Kaley must pull off miracles to stop this new invasion of Earth.