External snort monitoring

["Larry E. Smith Jr." <lsmithjr () monster-solutions net>]

I have my cable modem hooked into a Linksys 5 port hub and I also have a snort sensor configured on the hub to catch 
all traffic coming to my network. from the 5 port hub it connects into a Linksys router which is where my server is 
located. my question is why can i catch traffic on my internal snort sensor connected to the Linksys router, but all I 
can see are ARP requests on the external snort sensor which is connected to the hub? anyone have any ideas?