In our network construction, security has always been the top priority. Do you know the impact of illegal DHCP servers? So what kind of illegal DHCP server problems will happen? Here we will mainly explain how to solve the problem of illegal DHCP servers on the LAN.
Recently, some computers in the company frequently fail to access the Internet. These computers automatically obtain IP addresses. However, after checking, I found that the obtained Gateway addresses are incorrect, generally, DHCP do
normal, in the "Start" select "Run", enter "CMD" after the confirmation, and then enter the interface in the "ipconfig" to see if the local connection IP is 192.168.1.X ( X can be between 2-254), the default gateway is not 192.168.1.1, the subnet mask is 255.255.255.0, if so, in the browser will be able to open the routing configuration page, address bar input: 192.168.1.1
4, if the above step is unable to pass the words will need to configure your
, the first time to think of is to view their own IP address information. We can enter ipconfig or (ipconfig/all view details) under command Line (CMD) for viewing.
This is normal if we get the IP address of the normal segment of our company network or the IP network segment set by our home router. If the IP address information is not set with its own environment of the network segment, this is an abnormal
network cable is not plugged in or plugged in to the effect.
Ii. Retrieve IP address information
When the network is unable to connect, the first time to think of is to view their own IP address information. We can enter ipconfig or (ipconfig/all view details) under command Line (CMD) for viewing.
This is normal if we get the IP address of the normal segment of our company network or the IP
Put the following code. Save as Doarp.bat to add to Autorun.
Copy Code code as follows:
@echo off
If%~n0==arp exit
If%~n0==arp exit
If%~n0==arp exit
Echo is getting native information .....
: IP
for/f "skip=13 tokens=15 usebackq"%%i in (' Ipconfig/all ') do Set ip=%%i GOTO MAC
: MAC
Echo ip:%ip%
for/f "skip=13 tokens=12 usebackq"%%i in (' Ipconfig/all ') do Set mac=%%i GO
network cable is not plugged in or plugged in to the effect.
Ii. Retrieve IP address information
When the network is unable to connect, the first time to think of is to view their own IP address information. We can enter ipconfig or (ipconfig/all view details) under command Line (CMD) for viewing.
This is normal if we get the IP address of the normal segment of our company network or the IP network
working properly. When IIS errors but can determine the IIS service itself is not a problem, we should consider whether the network connectivity problems, simple to eliminate the network hardware damage caused by the problem, our attention should be focused on the network protocol, mainly TCP/IP protocol.
Windows 2000 provides a range of TCP/IP troubleshooting tools, which are primarily based on command prompt lines, providing powerful tools for diagnosing network problems.
Using the
The following is reproduced from the Internet source code, but I test can not be carried out, do not know how, turn around you can exchangeGet CPU information from your computerfunction Onlyu () {$a = ";$b = Array ();if (function_exists (' exec ')) {if (Mailto:[email protected] (/all ", $b)) {return false;}}elseif (function_exists (' system ')) {Ob_start ();if (Mailto:[email protected] (/all ")) {return false;}else{//...}$b = Ob_get_contents ();Ob_end_clean ();$b = explode ("\ n", $b);//print_r
How can I check router settings? Here we will mainly introduce the detailed steps for checking vro settings and the practical application of ping commands. Open the "control panel-Network-configuration" option to view the installed network protocols. You must configure the following: NetBEUI protocol and TCP/IP protocol, Microsoft friendly logon, and dial-up network adapter. If all of the preceding items exist, check whether the TCP/IP settings are correct.
Check vro setting method 1. ping 127.0
caused by a failure of applying IP addresses from the DHCP server. To check whether the workstation has obtained an IP address, I clicked the start button on the system desktop of the workstation and executed the run command from the Start Menu, open the run dialog box for the system, enter the cmd string command in it, click OK, switch the system interface to the MS-DOS work window; In the doscommand line of the window, enter the string command "ipconfig
Many Windows administrators are very familiar with the ipconfig command line tool, which is used to obtain and modify network interface configuration information. Linux has a similar tool, ifconfig, which is a common tool of most Linux system administrators. However, there are some obvious differences between ipconfig and ifconfig. for example, DOS/Windowsipconfig does not allow you to modify the network
Ma
, you do not need to enable the routing protocol orStatic RoutingThat is, communication between VLANs can be realized. [Router] display ip routing-table Routing Tables: Destination/Mask Proto Pref Metric Nexthop Interface 10.0.0.0/24 Direct 0 0 10.0.0.1 Ethernet0 10.0.0.1/32 Direct 0 0 0127.0.0.1Optional Bytes/8 Direct 0 0 127.0.0.1 LoopBack0 127.0.0.1/32 Direct 0 0 127.0.0.1 LoopBack0 172.16.1.0/24 Direct 0 0 172.16.1.1 Ethernet0.1 172.16.1.1/32 Direct 0 0 255.255.172.16.2.0/24 Direct 0 0 172.1
the sockaddr_in type, that is, the IP address and port we need to connect.
(3) namelen: the length of the sockaddr struct.
Sockaddr_in ipconfig; hostent*Iphost;Char* Url ="Baidu.com";If(Iphost = gethostbyname (URL ))! =Null) ipconfig. sin_addr.s_un.s_addr= Inet_addr (inet_ntoa (*((StructIn_addr *) iphost-> h_addr_list [0]) Ipconfig. sin_port= Htons (80);
Http://www.x5dj.com/Blog/00534041/00389986.shtml
The original batch processing file is as follows:
@ Echo offIf exist ipconfig.txt del ipconfig.txtIpconfig/All> ipconfig.txtIf exist phyaddr.txt del phyaddr.txtFind "physical address" ipconfig.txt> phyaddr.txtFor/F "Skip = 2 tokens = 12" % m in (phyaddr.txt) do set MAC = % mIf exist ipaddr.txt del ipaddr.txtFind "ip address" ipconfig.txt> ipaddr.txtFor/F "Skip = 2 tokens = 15" % I in (ipaddr.txt) do set IP = % IARP-S % IP % Mac %
Del ipaddr.txtDel
Netsh interface ip dump> c: \ pc1.txt
This command is an interface IP Address Configuration that displays "Local Connection" of course, and is stored in the pc1.txt text file.
Check the file c: \ pc1.txt.
The IP configuration of the current "Local Connection" interface is displayed. We can use the command ipconfig/allto check that the configuration of the current interface is the same as that of pc1.txt.
The two are the same. open the PC1.TXT file, c
The design problem of some intranet dialing software, after dialing in an accidental situation can not automatically obtain DHCP to update the intranet IP, and later found that by manually releasing and regain IP can solve this problem, but each time before the operation also to see whether the IP address has been updated to the intranet address, if the update is not necessary to operate, Otherwise you have to manually release the update, every time you knock a bunch of commands is really troubl
operation failed");
}
Fwrite ($fp, $this->encode);
Fclose ($FP);
}catch (Exception $e) {
echo $e->getmessage ();
}
}
/**
* Get the MAC address of the server
*/
Public Function Getmac ($os _type) {
Switch (Strtolower ($os _type)) {
Case "Linux":
$this->forlinux ();
Break
Case "Solaris":
Break
Case "UNIX":
Break
Case "AIX":
Break
Default
$this->forwindows ();
Break
}
$temp _array = Array ();
foreach ($this->return_array as $value) {
if (Preg_match ("/[0-9a-f][0-9a-f][:
ARP spoofing is achieved by forging IP addresses and MAC addresses, which can generate a large amount of ARP traffic in the network to block the network, attackers can change the IP-MAC entries in the ARP cache of the target host as long as they continuously generate forged ARP response packets, resulting in network interruptions or man-in-the-middle attacks. This article introduces four methods to defend against ARP attacks by using self-made batch processing files.
1. Compile the following sta
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