Questionable Security Log Events

i discovered weird events in security logs of 1 of our servers , need help.

we noticed number of sucessful logon (540) , logoff (538) codes, instead of user account computer name "$" @ end. found anonymous logons user well.

the security log looks this:

type                 date                  time         source      category       event         user                 computer

success audit    01/24/2012    9:35:10 am    security    logon/logoff    540    companypc005$     dataserver01

success audit    01/24/2012    9:45:10 am    security    logon/logoff    538    companypc005$     dataserver01

success audit    01/24/2012    9:35:10 am    security    logon/logoff    540    anonymous logon     dataserver01

success audit    01/24/2012    9:45:10 am    security    logon/logoff    538    anonymous logon     dataserver01

 

i'll check our local firewall , see being allowed, can tell me computername$ means? @ first thought may non-domain systems (we have subcontractors), of systems in the security log domain systems.

any insight on might causing , how prevent be greatly appreciated! 

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-- sam athanassov

i don't know services running on computer other computer contact.

so need determine services on machine. or may computer has same name previous machine in network , other computers contacting because of incorrect configuration trying access available services.

one note anonymous logon:

for example, if there normal user on other computers try access server on shared files (such \\yourserver\someshare). @ point, client computers in question (the companypc005$ etc.) may anonymous query list of shared folders (just offer them automaticly list in address bar). computers may under conditions try obtain dfs namesapces information \\yourserver machine, authenticated under (companypc005$) computer account. after these 2 processes, client computers access shared folder on \\yourserver under logged on user's identity. may explain events in greater detail.

Windows Server  >  Security