Seeing traffic destined for other people's servers in wireshark

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http://serverfault.com – I rent a dedicated server from a hosting provider. I ran wireshark on my server so that I could see incoming HTTP traffic that was destined to my server. Once I ran wireshark and filtered for HTTP I noticed a load of traffic, but most of it was not for stuff that was hosted on my server and had a destination IP address that was not mine, there were various source IP addresses. My immediate reaction was to think that somebody was tunnelling their HTTP traffic through my server somehow. However when I looked closer I noticed that all of this traffic was going to hosts on the same subnet and al ()