servers are client OS-independent. a good deal of dedicated servers run linux, and half-life don't do linux. the problem is more than likely one of two things:
1)the server
2)your friend
hope that narrows it down!
j/k. if the server is properly set up, then you are correct, he should check to make sure his networking is properly set up (i.e. can he access web pages and what not?) and then make sure that he doesnt have access to that program (half life?) disabled by any firewalls...does he have zone alarm installed?
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