Author: admin

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L’ammostamento – Concetti base

L’ammostamento (in inglese Mashing, da to mash, che significa impastare o miscelare), e’ la fase del procedimento all grain che permette di disgregare le eventuali proteine presenti nel malto e produrre zuccheri, definendo il rapporto tra maltosio e destrosio. Senza addentrarci troppo in caratteri tecnici, bastera’ sapere che ammostando a temperature diverse otterremo risultati leggermente diversi: questo e’ per esempio un vantaggio della birra all grain. Ecco per esempio alcune temperature e i rispettivi risultati:

Tra 50 e 52 gradi disgreghiamo le proteine, questo serve per rendere piu’ limpida e stabile la birra, e per migliorare la schiuma: di solito questo step si usa in all grain per il malto Pilsner e dura dai 15 ai 30 minuti.

Tra 60 e 65 gradi si ottiene piu’ maltosio e in pratica si ottiene leggermente piu’ alcol rispetto a temperature piu’ elevate; il tempo di ammostamento per i malti moderni si aggira tra i 30 e i 60 minuti.

Tra 68 e 70 gradi si produce piu’ destrosio che in concreto si traduce con un maggior corpo nella birra; anche qui l’ammostamento puo’ variare dai 30 ai 60 minuti.

A 78 gradi invece di routine facciamo il Mash-Out (questo passaggio sarebbe meglio farlo sempre, anche quando non viene specificato nella ricetta), questo step serve a finire il processo di mash e di solito dura 15 minuti.

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Directly Connected and Remote Network Routes

The destination network entries in the routing table can be added in several ways:

  • Local Route interfaces – These are added when an interface is configured and active. This entry is only displayed in IOS 15 or newer for IPv4 routes, and all IOS releases for IPv6 routes.
  • Directly connected interfaces – These are added to the routing table when an interface is configured and active.
  • Static routes – These are added when a route is manually configured and the exit interface is active.
  • Dynamic routing protocol – This is added when routing protocols that dynamically learn about the network, such as EIGRP or OSPF, are implemented and networks are identified.

Dynamic routing protocols exchange network reachability information between routers and dynamically adapt to network changes. Each routing protocol uses routing algorithms to determine the best paths between different segments in the network, and updates routing tables with these paths.

Dynamic routing protocols have been used in networks since the late 1980s. One of the first routing protocols was RIP. RIPv1 was released in 1988. As networks evolved and became more complex, new routing protocols emerged. The RIP protocol was updated to RIPv2 to accommodate growth in the network environment. However, RIPv2 still does not scale to the larger network implementations of today. To address the needs of larger networks, two advanced routing protocols were developed: Open Shortest Path First (OSPF) and Intermediate System-to-Intermediate System (IS-IS). Cisco developed the Interior Gateway Routing Protocol (IGRP) and Enhanced IGRP (EIGRP), which also scales well in larger network implementations.

Additionally, there was the need to connect different internetworks and provide routing between them. The Border Gateway Protocol (BGP) is now used between Internet Service Providers (ISPs). BGP is also used between ISPs and their larger private clients to exchange routing information.

The table classifies the protocols. Routers configured with these protocols will periodically send messages to other routers. As a cybersecurity analyst, you will see these messages in various logs and packet captures.

Protocol Interior Gateway Protocols Exterior Gateway Protocols
Distance Vector Link State Path Vector
IPv4 RIPv2 EIGRP OSPFv2 IS-IS BGP-4
IPv6 RIPng EIGRP for IPv6 OSPFv3 IS-IS for IPv6 BGP-MP
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Run script with jenkins as root

create the script with jenkins group : /pathtoscript.sh

vim /etc/sudoers

add the following row to the conf sudoers file

jenkins    ALL=(ALL)  NOPASSWD: /pathtoscript.sh

be carefull only root can read write execute , jenkins can read and execute not write

chmod 750 /pathtoscript.sh

 

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testIP Address Classes

  • IP class A addresses have first octets with a decimal number from 1 to 127. Example: 27.x.y.z 102.x.y.z
  • IP class B addresses have first octets with a decimal number from 128 to 191.Example: 128.x.y.z 151.x.y.z
  • IP class C addresses have first octets with a decimal number from 192 to 223.Example: 192.x.y.z 223.x.y.z
  • IP class D addresses have decimal values from 224 to 239 in the first octet, and the 4 leftmost bits are 1110.Example: 224.x.y.z 239.x.y.z
  • The last IP address class of addresses is IP class E. IP class E addresses range from 240 to 255 in the first octet, and the 4 leftmost bits are 1111. Example: 240.x.y.z 255.x.y.z

from here

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Difference between Hub, Switch and Router

Sr. No Hub Switch Router
1. Hub is a physical layer device i.e. layer 1. Switch is a data link layer device i.e. layer 2. Router is a network layer device i.e. layer 3.
2. A Hub works on the basis of broadcasting. Switch works on the basis of MAC address. A router works on the basis of IP address.
3. A Hub is a multiport repeater in which a signal introduced at the input of any port appears at the output of the all available ports. A Switch is  a tele-communication  device which receives a message from any device connected to it and then transmits the message only to the device for which the message is intended. A router reads the header of incoming packet and forward it to the port for which it is intended there by determines the route. It can also perform filtering and encapsulation.
4. Hub is not an intelligent device that may include amplifier on repeater. A Switch is an intelligent device as it passes on the message to the selective device by inspecting the address. A route is more sophisticated and intelligent device as it can read IP address and direct the packets to another network with specified IP address. Moreover routers can built address tables that helps in routing decisions.
5. At least single network is required to connect. At least single network is required to connect. Router needs at least two networks to connect.
6. Hub is cheaper as compared to switch and router. Switch is an expensive device than hub. Router is a relatively much more expensive device than hub and switch.

An Ethernet hub acts as a multiport repeater that receives an incoming electrical signal (data) on a port. It then immediately forwards a regenerated signal out all other ports. Hubs use physical layer processing to forward data. They do not look at the source and destination MAC address of the Ethernet frame. Hubs connect the network into a star topology with the hub as the central connection point. When two or more end devices connected to a hub send data at the same time, an electrical collision takes place, corrupting the signals. All devices connected to a hub belong to the same collision domain. Only one device can transmit traffic at any given time on a collision domain. If a collision does occur, end devices use CSMA/CD logic to avoid transmission until the network is clear of traffic. Due to the low cost and superiority of Ethernet switching, hubs are seldom used today.

Bridges have two interfaces and are connected between hubs to divide the network into multiple collision domains. Each collision domain can have only one sender at a time. Collisions are isolated by the bridge to a single segment and do not impact devices on other segments. Just like a switch, a bridge makes forwarding decisions based on Ethernet MAC addresses. Bridges are seldom used in modern networks.

LAN switches are essentially multiport bridges that connect devices into a star topology. Like bridges, switches segment a LAN into separate collision domains, one for each switch port. A switch makes forwarding decisions based on Ethernet MAC addresses. The figure shows the Cisco series of 2960-X switches that are commonly used to connect end devices on a LAN.