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afabco
Guru
Joined: 24 Feb 2004
Posts: 380
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 Posted: Wed Jul 30, 2008 11:29 pm Post subject: sending a hex string to a remote via netcat? |
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Hey folks,
I've got some binary commands (which I'm representing as hex) that I need to send to a remote device (it's an embedded data collection device) and observe the reply.
It's easy to connect to it with netcat
| Code: | | nc -v 192.168.200.34 19000 |
and it sits there happy as a clam.
The hex string I need to send is something like:
| Quote: | 05:64:10:D3:FD:00:00:00:E7:30:F5:C6:01:3C:02:07:1E:3C:03:07:1E:E7:59
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But when I type this into my netcat window (with or without spaces , with or without the colons) netcat transmits it as ascii.
All the literature is happy to tell me how to capture a hexdump from the remote device, but not how to transmit binary/hex data to the remote device.
Is this an easy thing to do, or am I missing something?
thanks!
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Hu
Administrator
Joined: 06 Mar 2007
Posts: 23087
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| Posted: Thu Jul 31, 2008 3:12 am Post subject: |
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Netcat will forward its input unmodified. Your best bet would be to find or make a tool that reads hexadecimal numbers and prints the corresponding bytes onto its standard output. Then do helper-cmd | nc 192.168.200.34 19000.
If you could write the data in base64 instead, then the coreutils program /usr/bin/base64 could transform your data into raw bytes for the wire. |
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coolsnowmen
Veteran
Joined: 30 Jun 2004
Posts: 1479
Location: No.VA
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| Posted: Thu Jul 31, 2008 7:40 pm Post subject: |
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perhaps something like this (compile with g++ filename.c)
| Code: | #include <cstdio>
#include <string>
//Written by Coolsnowmen for free
int hex2int(char &hex)
{
const static std::string key("0123456789abcdef");
return key.find( hex | 32 );
}
int main(int argnum,char ** argin)
{
if (argnum==2) {
int length=strlen(argin[1]);
if (length%2==0) {
for (int idx =0; idx<length; idx+=2)
printf("%c",hex2int(argin[1][idx])*16 + hex2int(argin[1][idx+1]));
return 0;
}
else {
fprintf(stderr,"non-even length string");
}
} else printf("1 argument expexted, of hexpairs, eg: %s 4a4f4e --> JON",argin[0]);
return 1;
} |
testing:
| Code: | ./a.out 000102030405 | wc
0 0 6 |
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