Hades has a hell of a firewall in this WebMage novel from Kelly McCullough.

Not just any computer geek can hack into Hades. But Ravirn, a direct descendant of one of the three Fates, is no ordinary hacker. Magic has gone digital in the twenty-first century, and Ravirn is a sorcerer with a laptop-otherwise known as his shape-changing best friend.

These days, Ravirn's crashing at his girlfriend's place while she works on her doctorate in computer science. Only one problem: all of her research is in her webgoblin's memory, which is now in Hades along with its soul. To save Cerice's webgoblin (and her PhD), Ravirn must brave Hell itself. But can he do it without corrupting the mweb-the magical internet-and without facing down the Lord of the Dead himself?