[linux command] xxd

wireshark 같은 프로그램을 보게 되면 hex로 된 string과 그냥 string 등으로 view를 바꿀 수 있다.

linux에서는 xxd라는 명령어로 hex와 일반 string을 변경할 수 있다.

xxd - make a hexdump or do the reverse.

[예시]

file

GET / HTTP/1.1

Accept: image/jpeg, application/x-ms-application, image/gif, application/xaml+xml, image/pjpeg, application/x-ms-xbap, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*

Accept-Language: ko-KR

User-Agent: Mozilla/4.0 ()

Accept-Encoding: gzip, deflate

Host: local.host

Connection: Keep-Alive

xxd file

0000000: 4745 5420 2f20 4854 5450 2f31 2e31 0a41  GET / HTTP/1.1.A

0000010: 6363 6570 743a 2069 6d61 6765 2f6a 7065  ccept: image/jpe

0000020: 672c 2061 7070 6c69 6361 7469 6f6e 2f78  g, application/x

0000030: 2d6d 732d 6170 706c 6963 6174 696f 6e2c  -ms-application,

0000040: 2069 6d61 6765 2f67 6966 2c20 6170 706c   image/gif, appl

0000050: 6963 6174 696f 6e2f 7861 6d6c 2b78 6d6c  ication/xaml+xml

0000060: 2c20 696d 6167 652f 706a 7065 672c 2061  , image/pjpeg, a

0000070: 7070 6c69 6361 7469 6f6e 2f78 2d6d 732d  pplication/x-ms-

0000080: 7862 6170 2c20 6170 706c 6963 6174 696f  xbap, applicatio

0000090: 6e2f 766e 642e 6d73 2d65 7863 656c 2c20  n/vnd.ms-excel,

00000a0: 6170 706c 6963 6174 696f 6e2f 766e 642e  application/vnd.

00000b0: 6d73 2d70 6f77 6572 706f 696e 742c 2061  ms-powerpoint, a

00000c0: 7070 6c69 6361 7469 6f6e 2f6d 7377 6f72  pplication/mswor

00000d0: 642c 202a 2f2a 0a41 6363 6570 742d 4c61  d, */*.Accept-La

00000e0: 6e67 7561 6765 3a20 6b6f 2d4b 520a 5573  nguage: ko-KR.Us

00000f0: 6572 2d41 6765 6e74 3a20 4d6f 7a69 6c6c  er-Agent: Mozill

0000100: 612f 342e 3020 2829 0a41 6363 6570 742d  a/4.0 ().Accept-

0000110: 456e 636f 6469 6e67 3a20 677a 6970 2c20  Encoding: gzip,

0000120: 6465 666c 6174 650a 486f 7374 3a20 6c6f  deflate.Host: lo

0000130: 6361 6c2e 686f 7374 0a43 6f6e 6e65 6374  cal.host.Connect

0000140: 696f 6e3a 204b 6565 702d 416c 6976 650a  ion: Keep-Alive.

xxd file > hexa_file 로 hexa_file을 생성한다.

xxd로 수정된 hex 데이터를 다시 수정하려면 아래 명령어를 사용하면 된다.

xxd -r hexa_file

GET / HTTP/1.1

Accept: image/jpeg, application/x-ms-application, image/gif, application/xaml+xml, image/pjpeg, application/x-ms-xbap, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*

Accept-Language: ko-KR

User-Agent: Mozilla/4.0 ()

Accept-Encoding: gzip, deflate

Host: local.host

Connection: Keep-Alive

이걸 .vimrc에 넣고 사용해보자. 

map <F5>    <ESC>:%!xxd<CR>

map <F6>    <ESC>:%!xxd -r<CR>

hexa로 보고 싶은 파일을 vi로 열고 <F5> 를 누르면 hexa string으로 보인다.

<F6>을 누르면 다시 일반 string으로 변할 것이다.