Generally, the company will have a limit (somewhere in the $25-$50 range) on gifts you could give or receive without prior authorization. So maybe I can take you to a bar or coffee shop and get you a drink or two while we talk. But not a dinner at a high end restaurant, or a sporting event or a vacation in Hawaii, because the risk of being corrupted (on the receiving end) or reputational risk from being seen as corrupt, was too great.
This is particularly potent issue for American companies because of the Foreign Corrupt Practices Act. The FCPA means that US companies (and their subsidiaries, contractors, etc.) have to draw these sorts of lines over the entire world, or be subject to heavy penalties, even in countries where it might be more common and legal.
One area that's more fuzzy is free passes to user events, i.e., a DreamForce or Oracle World. We clear these per our process and are fine to accept them because we were going to spend money on sending someone anyway. We saved the company money. Also: it was never indirect between individuals, it was company to company.