Securing an accessible computer system typically includes receiving a data packet that includes a payload portion and an attribute portion, where the data packet is communicated between at least one access requestor and at least one access provider. At least the payload portion of the received data packet typically is monitored, where monitoring includes scanning the payload portion for at least one predetermined pattern. When the payload portion is determined to include at least one predetermined pattern, access by the access requestor to the access provider may be controlled. Monitoring the data packet may include scanning the payload portion while handling the data packet with a switch. Controlling access may include denying access by the access requestor to the access provider.