前段時(shí)間接到一個(gè)項(xiàng)目,該項(xiàng)目要求在局域網(wǎng)內(nèi)的任何一臺(tái)計(jì)算機(jī)上安裝一套計(jì)費(fèi)軟件,其他的客戶端不用安裝任何軟件,只要客戶插入網(wǎng)線就可以計(jì)費(fèi)。以前接觸到的計(jì)費(fèi)軟件都是安裝在網(wǎng)關(guān)上的,要么就是要安裝客戶端軟件,如何實(shí)現(xiàn)這樣的功能呢?研究了一下,發(fā)現(xiàn)用arp欺騙的原理可以實(shí)現(xiàn)計(jì)費(fèi)的功能,原理是在未開通上網(wǎng)功能的客戶端插入網(wǎng)線后,先禁止局域網(wǎng)內(nèi)的該計(jì)算機(jī)上網(wǎng),等該客戶端要求管理員開通上網(wǎng)功能后再解除對(duì)該客戶端的阻止并開始計(jì)費(fèi)。arp欺騙相信大家的都不陌生,網(wǎng)上有好多介紹arp欺騙的文章,也有好多arp欺騙的病毒,在這里就不再重復(fù)arp欺騙的原理了。
如何阻止局域網(wǎng)指定的客戶端上網(wǎng)呢? 用偽造的arp的請(qǐng)求包刷新要阻止機(jī)器的arp表,使之認(rèn)為網(wǎng)關(guān)的mac地址為一個(gè)不存在的mac地址,這樣的話就可以阻止該機(jī)器上網(wǎng)了。
假設(shè)要阻止的計(jì)算機(jī)是A,安裝計(jì)費(fèi)軟件的計(jì)算機(jī)是B,網(wǎng)關(guān)是C
A機(jī)器 MAC:AA-AA-AA-AA-AA-AA IP地址:192.168.1.1
B機(jī)器 MAC:BB-BB-BB-BB-BB-BB IP地址:192.168.1.2
C網(wǎng)關(guān) MAC:CC-CC-CC-CC-CC-CC IP地址:192.168.1.253
在網(wǎng)上有好多arp例子都是c的,我用delphi和Winpcap實(shí)現(xiàn)代碼如下: 安裝Winpcap,引用:winsock,Packet32,shellapi單元
類型和常量定義: type TMacAddr = array [0..5] of byte ; TEHHDR=packed record Ether_Dest: TMacAddr ; {目的地址 } Ether_Src: TMacAddr ; {源地址 } Ether_Type:Word; {類型 } end; PEHHDR=^TEHHDR; TEtherData=packed record {Ethernet packet data} Ether_hrd:WORD; {hardware address } Ether_pro:WORD; {format of protocol address } Ether_hln: byte; {byte length of each hardware address } Ether_pln: byte; {byte length of each protocol address} Ether_op:WORD; { ARP or RARP } Ether_sha:TMacAddr; {hardware address of sender} Ether_spa:LongWord; {protocol address of sender} Ether_tha:TMacAddr; {hardware address of target} Ether_tpa:LongWord; {protocol address of target} end; PARPHDR=^TEtherData;
TARPPACKET=packed record EHHDR:Tehhdr; EtherData:TEtherData; end ; PARPPACKET=^TARPPACKET;
const INADDR_NONE = $FFFFFFFF; EPT_IP = $0800; EPT_ARP = $0806 ; EPT_RARP =$8035 ; ARP_REPLY =$0002 ; ARP_REQUEST = $0001 ; ARP_HARDWARE =$0001 ;
function inet_addr(const cp: PChar): DWord; stdcall; external 'WS2_32.DLL' name 'inet_addr';
//別人的代碼 function HexStrtoInt(var Buf: string): dword; //將十六進(jìn)制的字符串轉(zhuǎn)成整型 //判斷是否是十六進(jìn)制數(shù) function IsHexChar(Chr: char): boolean; begin Result := (Chr in ['0'..'9']) or (Chr in ['A'..'F']); end; //將一個(gè)十六進(jìn)制字符轉(zhuǎn)換成數(shù) function HexChrtoInt(Chr: char): byte; begin Result := 0; case Chr of '0'..'9' : Result := Strtoint(Chr); 'A' : Result := 10; 'B' : Result := 11; 'C' : Result := 12; 'D' : Result := 13; 'E' : Result := 14; 'F' : Result := 15; end; end; var BufLength: dword; TempBuf: string; Count0: dword; begin Result := 0; BufLength := Length(Buf); TempBuf := ''; if BufLength > 0 then begin Buf := Uppercase(Buf); // for Count0 := 1 to BufLength if BufLength mod 2 = 1 then begin Buf := '0' + Buf; BufLength := Length(Buf); end; for Count0 := 1 to BufLength div 2 do if IsHexChar(Buf[Count0 * 2 - 1]) then begin if IsHexChar(Buf[Count0 * 2]) then begin TempBuf := TempBuf + inttostr(HexChrtoInt(Buf[Count0 * 2 - 1])
* 16 + HexChrtoInt(Buf[Count0 * 2])); end else begin Result := Count0 * 2; Break; end; end else begin Result := Count0 * 2 - 1; Break; end; if Result = 0 then Buf := TempBuf; end; end;
//MAC轉(zhuǎn)換 procedure GetMac(s : string;var Mac : TMacAddr);
var hs : string; p : integer; i,j:integer;
begin FillChar (Mac, SizeOf (Mac), 0) ;
i:=0; if Length(s)=0 then Exit; p:=Pos('-',s); while P<>0 do begin hs:=Copy(s,1,p-1); HexStrtoInt(hs); Mac[i]:= strtoint(hs) ; Delete(s,1,p); p:=Pos('-',s); i:=i+1; end; if Length(s)>0 then begin HexStrtoInt(s); Mac[i]:=strtoint(s); end; end;
{禁止上網(wǎng),發(fā)送arp請(qǐng)求包,這里的C_mac為偽造的C的mac地址} procedure SendArp(A_ip:string;A_mac:string;B_ip:string;B_mac:string;C_IP:string;C_mac:string); var ulMACAddr: TMacAddr; EHHDR:TEHHDR; EtherData:TEtherData; pp:pPacket; lpAdapter:Padapter; BUF:Array [0..512] of char ;
begin //以太網(wǎng)包首部 GetMac(A_mac,ulMACAddr); Move(ulMACAddr , EHHDR.Ether_Dest,6);//目的地址-A計(jì)算機(jī)的地址 GetMac(C_mac,ulMACAddr); Move(ulMACAddr , EHHDR.Ether_Src,6);//偽造的源地址-C計(jì)算機(jī)的地址 EHHDR.Ether_Type := htons(EPT_ARP);//arp包 //構(gòu)造以太網(wǎng)包數(shù)據(jù) EtherData.Ether_hrd := htons(ARP_HARDWARE); EtherData.Ether_pro := htons(EPT_IP); EtherData.Ether_hln := 6; EtherData.Ether_pln := 4; EtherData.Ether_op := htons(ARP_REQUEST);//arp請(qǐng)求包 GetMac(C_mac,ulMACAddr); Move(ulMACAddr , EtherData.Ether_sha,6); EtherData.Ether_spa := inet_addr(Pchar(B_IP)); GetMac(B_mac,ulMACAddr); Move(ulMACAddr , EtherData.Ether_tha,6); EtherData.Ether_tpa := inet_addr(Pchar(B_ip));
lpAdapter := PacketOpenAdapter('\Device\NPF_{E00872C1-37C0-47CE-8472-313A5A23F896}'); // 根據(jù)
你網(wǎng)卡名字打開網(wǎng)卡,這是我網(wǎng)卡的設(shè)備名 fillchar(BUF,sizeof(BUF),0);
CopyMemory(@BUF,@EHHDR,SIZEOF(EHHDR)); CopyMemory(Pointer(LongWord(@BUF)+SIZEOF(EHHDR)),@EtherData,SIZEOF(EtherData)); // 分配內(nèi)存 pp := PacketAllocatePacket();
//初始化結(jié)構(gòu)指針 PacketInitPacket(pp, @BUF,512); //發(fā)arp應(yīng)答包 PacketSendPacket(lpAdapter, pp, true); // 釋放內(nèi)存 PacketFreePacket(pp); PacketCloseAdapter(lpAdapter);
end;
//調(diào)用示例 SendArp('192.168.1.1','AA-AA-AA-AA-AA-AA','192.168.1.2','BB-BB-BB-BB-BB-BB','192.168.1.253','00-00-00-00-00-00');
{解除阻止,發(fā)送arp應(yīng)答包,這里的C_mac為真實(shí)的C的mac地址} procedure SendArpReply(A_ip:string;A_mac:string;C_ip:string;C_mac:string;B_mac:string); var ulMACAddr: TMacAddr; EHHDR:TEHHDR; EtherData:TEtherData; pp:pPacket; lpAdapter:Padapter; BUF:Array [0..512] of char ;
begin GetMac(A_mac,ulMACAddr); Move(ulMACAddr , EHHDR.Ether_Dest,6); GetMac(B_mac,ulMACAddr); Move(ulMACAddr , EHHDR.Ether_Src,6); EHHDR.Ether_Type := htons(EPT_ARP); EtherData.Ether_hrd := htons(ARP_HARDWARE); EtherData.Ether_pro := htons(EPT_IP); EtherData.Ether_hln := 6; EtherData.Ether_pln := 4; EtherData.Ether_op := htons(ARP_REPLY);//arp應(yīng)答包 GetMac(C_mac,ulMACAddr); Move(ulMACAddr , EtherData.Ether_sha,6); EtherData.Ether_spa := inet_addr(Pchar(C_ip)); GetMac(A_mac,ulMACAddr); Move(ulMACAddr , EtherData.Ether_tha,6); EtherData.Ether_tpa := inet_addr(Pchar(A_ip));
// 根據(jù)自己網(wǎng)卡的設(shè)備名打開網(wǎng)卡 lpAdapter := PacketOpenAdapter('\Device\NPF_{E00872C1-37C0-47CE-8472-313A5A23F896}'); fillchar(BUF,sizeof(BUF),0); CopyMemory(@BUF,@EHHDR,SIZEOF(EHHDR)); CopyMemory(Pointer(LongWord(@BUF)+SIZEOF(EHHDR)),@EtherData,SIZEOF(EtherData));
// 分配內(nèi)存 pp := PacketAllocatePacket();
//初始化結(jié)構(gòu)指針 PacketInitPacket(pp, @BUF,512); //發(fā)arp應(yīng)答包 PacketSendPacket(lpAdapter, pp, true); // 釋放內(nèi)存 PacketFreePacket(pp); PacketCloseAdapter(lpAdapter); end;
//調(diào)用示例 SendArpReply('192.168.1.1','AA-AA-AA-AA-AA-AA','192.168.1.253','CC-CC-CC-CC-CC-CC','BB-BB-BB-BB-BB-BB');
需要注意的是,發(fā)出偽造的arp請(qǐng)求包過一段時(shí)間后會(huì)被刷新為正確的,所以每隔一段時(shí)間要向被阻止的機(jī)器發(fā)送一個(gè)arp包,這樣才能達(dá)到阻止上網(wǎng)的目的。
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