Here are two solutions and the problem.
cheako@arcadia:~$ perl
warn unpack("B620",pack(
'B8 C3 N10 B32',
          '00100011',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          1425691777,
          761152,
          '0',
          '0',
          1425691777,
          761152
));
00100011000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
01010100111110100101010010000001
00000000000010111001110101000000
00000000000000000000000000000000
00000000000000000000000000000000
01010100111110100101010010000001
10111000000000000000000000000000 at - line 1.

Different output, but identical input :/.

cheako@arcadia:~$ perl
warn unpack("B620",pack(
'B8 C3 N11',
          '00100011',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          1425691777,
          761152,
          '0',
          '0',
          1425691777,
          761152
));

cheako@arcadia:~$ perl
warn unpack("B620",pack(
'B8 C3 N11',
          '00100011',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          1425691777,
          761152,
          '0',
          '0',
          1425691777,
          761152
));
00100011000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
01010100111110100101010010000001
00000000000010111001110101000000
00000000000000000000000000000000
00000000000000000000000000000000
01010100111110100101010010000001
00000000000010111001110101000000 at - line 1.


cheako@arcadia:~$ perl
warn unpack("B620",pack(
'B8 C3 N10 B32',
          '00100011',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          '0',
          1425691777,
          761152,
          '0',
          '0',
          1425691777,
          '00000000000010111001110101000000'
));

00100011000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
00000000000000000000000000000000
01010100111110100101010010000001
00000000000010111001110101000000
00000000000000000000000000000000
00000000000000000000000000000000
01010100111110100101010010000001
00000000000010111001110101000000 at - line 1.

[download]

I've a lot of experience with pack and unpack and every time I learn something new, seems they never behave the way one would think they should. Check it with a warn unpack("B384",$send_sntp_packet) the best thing you can do at times like this is add in warn every branch.

my@argsforpacksend_sntp_packet=($client_li_vm_mode ,
+ $client_stratum , $client_poll , $client_precision , $client_root_de
+lay , $client_dispersion , $client_reference_identifier , $client_ref
+erence_timestamp_sec , $client_reference_timestamp_microsec , $client
+_originate_timestamp_sec , $client_originate_timestamp_microsec , $cl
+ient_receive_timestamp_sec , $client_receive_timestamp_microsec , $cl
+ient_transmit_sec , $client_transmit_microsec);  warn Dumper \@argsfo
+rpacksend_sntp_packet;
  my $send_sntp_packet = pack "B8 C3 N10 B32", @argsforpacksend_sntp_p
+acket;
warn unpack("B384",$send_sntp_packet)

[download]
Wrap each call to pack/unpack like this and you'll see what's wrong.

In reply to Re: SNTP pack and unpack by cheako
in thread SNTP pack and unpack by thanos1983

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