Such places as this exist. Freetowns, hidden in the lower sections of ships or stations or arcologies, where a few hundred people make their homes, strike up some sort of barter economy, and live in relative security. Often, prison stations will put problem inmates in something of a hole, where they are separated from the maintained sections of the ship.
Aboard the BPT)Black.River, a freetown of roughly six hundred people thrives beneath the ebb and flow of the Bretonia/Rhienland indentured prisoner/diamond exchange. Beneath the administration of Hadrian Applegate, this tiny community is a focal point for trades of any merchandise mankind can demand, a moving marketplace which calls on links to junker trade networks, outcast smugglers, Hessian diamond carvers, London Undercity markets, and a bustling artifact trade. It avoids notice by never sitting still, a ghost market that opens in a different square every day.