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Movements, leaders, victories and the continuing fight for equality.
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In August 1908, a white mob attacked Springfield, Illinois’s Black community, destroying homes and businesses and lynching two Black men. National outrage over the violence helped spur the movement that created the NAACP the following year.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
In computer security, an access-control list (ACL) is a list of permissions associated with a system resource (object or facility). An ACL specifies which users or system processes are granted access to resources, as well as what operations are allowed on given resources. Each entry in a typical ACL specifies a subject and an operation. For instance, If a file object has an ACL that contains(Alice: read,write; Bob: read), this would give Alice permission to read and write the file and give Bob permission only to read it. If the Resource Access Control Facility (RACF) profile CONSOLE CLASS(TSOAUTH) has an ACL that contains(ALICE:READ), this would give ALICE permission to use the TSO CONSOLE command.
A VLAN access control list (VACL) provides access control for all packets that are bridged within a VLAN or that are routed into or out of a VLAN. Unlike regular Cisco IOS access control lists that are configured on router interfaces and applied on routed packets only, VACLs apply to all packets. The technology was developed by Cisco on the Catalyst 6500 Series switch platform. VACLs may be used in similar fashion to a SPAN port or network tap, as a way to replicate computer network data that is coming into and leaving from a computer or a network. This is useful if you want to monitor traffic. Often, this configuration is used to facilitate data loss prevention (DLP) or network-based intrusion prevention systems. VACL or VACL Ports can be much more discriminating of the traffic they forward compared to a standard SPAN port. They may be set to only forward specific types or specific VLANs to the monitoring port. However, they forward all traffic that matches the criteria, as they do not have the functionality to select from ingress or egress traffic like SPAN ports.
In computer science, an access control matrix or access matrix is an abstract, formal security model of protection state in computer systems, that characterizes the rights of each subject with respect to every object in the system. It was first introduced by Butler W. Lampson in 1971. An access matrix can be envisioned as a rectangular array of cells, with one row per subject and one column per object. The entry in a cell – that is, the entry for a particular subject-object pair – indicates the access mode that the subject is permitted to exercise on the object. Each column is equivalent to an access control list for the object; and each row is equivalent to an access profile for the subject.
An access badge is a credential used to gain entry to an area having automated access control entry points. Entry points may be doors, turnstiles, parking gates or other barriers. Access badges use various technologies to identify the holder of the badge to an access control system. The most common technologies are magnetic stripe, proximity, barcode, smart cards and various biometric devices. The magnetic stripe ID card was invented by Forrest Parry in 1960. The access badge contains a number that is read by a card reader. This number is usually called the facility code and is programmed by the administrator. The number is sent to an access control system, a computer system that makes access control decisions based on information about the credential. If the credential is included in an access control list, the access control system unlocks the controlled access point. The transaction is stored in the system for later retrieval; reports can be generated showing the date/time the card was used to enter the controlled access point. The Wiegand effect was used in early access cards. This method was abandoned in favor of other proximity technologies. The new technologies retained the Wiegand upstream data so that the new readers were compatible with old systems. Readers are still called Wiegand but no longer use the Wiegand effect. A Wiegand reader radiates a 1" to 5" electrical field around itself. Cards use a simple LC circuit. When a card is presented to the reader, the reader's electrical field excites a coil in the card. The coil charges a capacitor and in turn powers an integrated circuit. The integrated circuit outputs the card number to the coil which transmits it to the reader. The transmission of the card number happens in the clear—it is not encrypted. With basic understanding of radio technology and of card formats, Wiegand proximity cards can be hacked. A common proximity format is 26 bit Wiegand. This format uses a facility code, also called a site code. The facility code is a unique number common to all of the cards in a particular set. The idea is an organization has their own facility code and then numbered cards incrementing from 1. Another organization has a different facility code and their card set also increments from 1. Thus different organizations can have card sets with the same card numbers but since the facility codes differ, the cards only work at one organization. This idea worked fine for a while but there is no governing body controlling card numbers, different manufacturers can supply cards with identical facility codes and identical card numbers to different organizations. Thus there is a problem of duplicate cards. To counteract this problem some manufacturers have created formats beyond 26 bit Wiegand that they control and issue to an organization. In the 26 bit Wiegand format bit 1 is an even parity bit. Bits 2-9 are a facility code. Bits 10-25 are the card number. Bit 26 is an odd parity bit. Other formats have a similar structure of leading facility code followed by card number and including parity bits for error checking. Smart cards can be used to counteract the problems of transmitting card numbers in the clear and control of the card numbers by manufacturers. Smart cards can be encoded by organizations with unique numbers and the communication between card and reader can be encrypted.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Joe Louis.