Explains how to configure and use Oracle Label Security, which provides row-level access control based on the virtual private database technology of Oracle Database Enterprise Edition. Explains how to configure an Oracle database to use Oracle Database Vault, which enables users to restrict and monitor administrative user access. Describes how to implement Real Application Security on the database.
Real Application Security is a new feature in Oracle Database 12c. Real Application Security is a database authorization model that enables end-to-end security for multitier applications. It provides an integrated solution to securing the database and application user communities.
Also, it advances the security architecture of Oracle Database to meet existing and emerging demands of applications developed for the Internet. Documents two Java packages: - oracle. Contains complete listing with descriptions of the control utility commands and configuration file parameters available for managing components of Oracle Net Services.
To counter these effects, the official BitTorrent client program uses a mechanism called 'optimistic unchoking', whereby the client reserves a portion of its available bandwidth for sending pieces to random peers not necessarily known good partners, so called preferred peers in hopes of discovering even better partners and to ensure that newcomers get a chance to join the swarm. Although 'swarming' scales well to tolerate 'flash crowds' for popular content, it is less useful for unpopular or niche market content.
Peers arriving after the initial rush might find the content unavailable and need to wait for the arrival of a 'seed' in order to complete their downloads. The seed arrival, in turn, may take long to happen this is termed the 'seeder promotion problem'. Since maintaining seeds for unpopular content entails high bandwidth and administrative costs, this runs counter to the goals of publishers that value BitTorrent as a cheap alternative to a client-server approach.
The peer distributing a data file treats the file as a number of identically sized pieces, usually with byte sizes of a power of 2, and typically between 32 kB and 16 MB each. The peer creates a hash for each piece, using the SHA-1 hash function, and records it in the torrent file.
Pieces with sizes greater than kB will reduce the size of a torrent file for a very large payload, but is claimed to reduce the efficiency of the protocol. The exact information contained in the torrent file depends on the version of the BitTorrent protocol.
By convention, the name of a torrent file has the suffix. Torrent files have an 'announce' section, which specifies the URL of the tracker, and an 'info' section, containing suggested names for the files, their lengths, the piece length used, and a SHA-1hash code for each piece, all of which are used by clients to verify the integrity of the data they receive.
Though SHA-1 has shown signs of cryptographic weakness, Bram Cohen did not initially consider the risk big enough for a backward incompatible change to, for example, SHA BitTorrent is now preparing to move to SHA In the early days, torrent files were typically published to torrent index websites, and registered with at least one tracker. The tracker maintained lists of the clients currently connected to the swarm. Azureus was the first [24] BitTorrent client to implement such a system through the distributed hash table DHT method.
After the DHT was adopted, a 'private' flag — analogous to the broadcast flag — was unofficially introduced, telling clients to restrict the use of decentralized tracking regardless of the user's desires.
The purpose of the flag is to prevent torrents from being shared with clients that do not have access to the tracker. The flag was requested for inclusion in the official specification in August , but has not been accepted yet. BitTorrent does not, on its own, offer its users anonymity. One can usually see the IP addresses of all peers in a swarm in one's own client or firewall program.
This may expose users with insecure systems to attacks. In some jurisdictions, copyright holders may launch lawsuits against uploaders or downloaders for infringement, and police may arrest suspects in such cases. Various means have been used to promote anonymity.
For example, the bittorrent client Tribler makes available a Tor-like onion network, optionally routing transfers through other peers to obscure which client has requested the data. The exit node would be visible to peers in a swarm, but the Tribler organization provides exit nodes.
One advantage of Tribler is that clearnet torrents can be downloaded with only a small decrease in download speed from one 'hop' of routing.
Most bittorrent clients are not designed to provide anonymity when used over Tor, [30] , and there is some debate as to whether torrenting over Tor acts as a drag on the network. Private torrent trackers are usually invitation only, and require members to participate in uploading, but have the downside of a single centralized point of failure. Oink's Pink Palace and What. Seedbox services download the torrent files first to the company's servers, allowing the user to direct download the file from there.
Virtual private networks encrypt transfers, and substitute a different IP address for the user's, so that anyone monitoring a torrent swarm will only see that address. A growing number of individuals and organizations are using BitTorrent to distribute their own or licensed works e.
Independent adopters report that without using BitTorrent technology, and its dramatically reduced demands on their private networking hardware and bandwidth, they could not afford to distribute their files. Some uses of BitTorrent for file sharing may violate laws in some jurisdictions see legal issues section. As of , BitTorrent had million users and a greater share of network bandwidth than Netflix and Hulu combined. Routers that use network address translation NAT must maintain tables of source and destination IP addresses and ports.
Typical home routers are limited to about table entries [ citation needed ] while some more expensive routers have larger table capacities. BitTorrent frequently contacts 20—30 servers per second, rapidly filling the NAT tables. This is a known cause of some home routers ceasing to work correctly. The BitTorrent protocol is still under development and may therefore still acquire new features and other enhancements such as improved efficiency.
On 2 May , Azureus 2. The following month, BitTorrent, Inc. Recent measurement shows users of Mainline DHT is from 10 million to 25 million, with a daily churn of at least 10 million. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. Performance Performance. Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors.
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