General access control is mainly set up in the firewall, the establishment of some security policies: such as the internal LAN resources do not allow the external users of the network; the undefended area (also known as the demilitarized Zone) can be used for internal or external local area networks, where resources are allowed to be limited to users of the extranet. ; You can enable external users to access the Web servers in the Demilitarized zone (
Use IP Address Spoofing to break through firewall deep technical analysis
General access control is mainly set in the firewall to develop some security policies: for example, the resources of the internal LAN are not allowed to be used by users on the external network; the area is not protected (also known as the non-military zone) it can be an internal or exte
25 machines, your task is to configure IP addresses and subnet masks for these machines. You may think this is simple. Apply for four class C addresses, one for each classroom, and then configure them one by one. Well, this is true in theory, but have you ever thought it would be a waste? You have wasted a total of (254-25) x 4 = 916 IP addresses, if all network administrators do this, the
, but the custom subnet mask, which is calculated by the Administrator) when performing the "and" operation, each subnet will get a different subnet address, thus realizing the division of the network (with a different address, of course, it will be able to differentiate each subnet, interesting ).
Subnet addressing technology, I .e., subnet partitioning, helps solve the following problems:
use of legitimate users: on the other hand, attackers may exploit this vulnerability to attack other machines and network devices in the subnet. If a proxy server exists in the subnet, hackers can also obtain out-of-network resources through various means.
Use Port location to block IP address theft in a timely manner
A switch is the main network device of a LAN
BR = new bufferedreader (is); While (line = Br. Readline ())! = NULL) {result + = line;} catch (exception e) {e. printstacktrace ();} return result;}/***** @ Param IP destination IP address, generally, the result string processed by the * @ Param sourcestring command in the LAN * @ Param macseparator Mac separator * @
The IP address is like a phone number, but the area code is required for dialing a phone number from another country. The subnet mask is required for accessing other network segments in the network. The IP address must be classified as if the IP
legitimate IP address.IP address = Network address + host address, (also known as: Host number and network number)The structure of IP addresses makes it easy to address on the Internet. The I
network number)The structure of IP addresses makes it easy to address on the Internet. The IP address is usually more intuitive, in dotted four decimal digits, each number from 0 to 255, such as the IP address of a host: 128.20.4
address = network address + host address (also known as host number and network number)The IP address structure enables convenient addressing on the Internet. Generally, IP addresses are displayed in four decimal numbers separate
packets will be handed over to the default gateway for processing, this will inevitably increase the burden on the default gateway, resulting in reduced network efficiency. Therefore, the subnet mask should be set based on the network size. If a network has no more than 254 computers, you can use "255.255.255.0" as the subnet mask. Currently, most local networks will not exceed this number, therefore, "255.255.255.0" is the most commonly used IP
The Internet is not always sunny, and there are dark clouds! This is not the case. When surfing the Internet, users often suffer from "harassment". Among them, the IP addresses that illegally steal others' workstation are the most common in LAN environments, this phenomenon seriously affects the efficient management and maintenance of LAN networks by network admi
vrouters. Therefore, each subnet must have an RARP server.
BOOTP (Bootstrap Protocol)
BOOTP is a high-level program. It can obtain the IP address, Startup File address, and configuration information through the RARP server. The BOOTP protocol uses the Client/Server working mode. The party that needs to obtain the configuration information is called The BOOTP cu
IPV4 Address:We know that at the network layer (the Internet layer of TCP/IP architecture), one of the most important protocols is IP protocol, is now in the IPV4 and IPv6 transition period, but at present, IPV4 is still mainstream, so the main Ipv4.Basic IP Address format:The format of the internal
" will be reserved for future use.
Iii. IP address addressing rules
1. network addressing rules
A. The network address must be unique.
B. The network ID cannot start with a number 127. In Class A addresses, the number 127 is reserved for the internal return function.
C. The first byte of the network logo cannot be 255. The number 255 is used as the broadcast
Create A point-to-point VPN for A fixed IP address of the network component. Create A point-to-point VPN for A fixed IP address of the network component router. one end of the network component router A is connected to the LAN. The internal
workstations in the LAN through the window. As a result, I found that the faulty workstation could access other workstations in the LAN smoothly, but you cannot access the server.
Fault Analysis
To test whether there is a line fault between the faulty workstation and the server, I first run the "Ping" command in the faulty workstation. The result shows that the server cannot be pinged normally, later, I ru
I have learned about computer networks, MAC addresses, IP addresses, route forwarding, and routing.Algorithm. At the same time, we also understand that IP addresses are 4 bytes divided into A, B, and C networks, and D broadcast e is retained, indicating that the number of networks and machines are limited. With the increasing number of computers, more and more IP
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