Contents
What is blocking protocol?
The blocking phenomena reduces availability of the system since the blocked transactions keep all the resources until they receive the final command from the coordinator after its recovery. To remove the blocking problem in 2PC protocol, the three phase commit (3PC) protocol was proposed.
Should I block port 139?
Port 139 is utilized by NetBIOS Session service. Enabling NetBIOS services provide access to shared resources like files and printers not only to your network computers but also to anyone across the internet. Therefore it is advisable to block port 139 in the Firewall.
Why 3PC is a blocking protocol?
Blocking consensus protocols The main motivation for the 3PC algorithm is to address the fact that two-phase commit protocol is blocking in case of a site (site means coordinator or participant) failure. The term blocking refers to the process of reaching the consensus on transaction commit[4].
How 3PC resolves the blocking problem of 2PC?
The 3PC protocol eliminates the 2PC protocol’s system blocking problem with the third phase preCommit. If the coordinator fails before sending a preCommit message, other processes will unanimously agree that the operation was aborted.
How to filter traffic using Extended Access Control List?
Using Extended Access Control List, we can filter traffic based on TCP or UDP port numbers or port names. Click the following link to know important TCP port numbers. You can specify a name also for TCP or UDP port numbers. For example, you can use the keyword smtp to match SMTP traffic (port number 25).
How are access control lists used in firewall?
Access control lists (ACLs) identify traffic flows by one or more characteristics, including source and destination IP address, IP protocol, ports, EtherType, and other parameters, depending on the type of ACL. ACLs are used in a variety of features.
What is a port and why should I block it?
What Is a Port? (and Why Should I Block It?) When used in construction or engineering, the term “firewall” means what it seems to mean: a wall capable of withstanding fire. It evokes something impenetrable, like a sheet of steel or a brick wall. However, in computer networking the term “firewall” means something porous.
What is the purpose of an access control list?
Definition of an Access List. Access control lists (ACLs) perform packet filtering to control the movement of packets through a network. Packet filtering provides security by limiting the access of traffic into a network, restricting user and device access to a network, and preventing traffic from leaving a network.