I had a similiar problem with Cisco Discovery Protocol. When the neighbors (switches/routers) showed up they included a "NULL" 00 HEX in the description which threw a new line into the output screwing up my logs. Here's How I fixed it. Create a "sub clean" which converts the string to hex, flushes out the hidden strings, converts back to ascii then returns the sanitized string. This has since solved all my output values...

 $item = caschex(1, $item); #A->H
 if($debug == 1) { print "HEX: \"$item\"\n"; }

 $item = caschex(2, $item); #H->A
 if($debug == 1) { print "ASCII: \"$item\"\n"; }

 $item =~ s/^\s+//; #remove Leading whitespace
 $item =~ s/\s+$//; #remove trailing whitespace
 $item =~ s/\s+/ /g; #replace multiple spaces with one
 chomp($item); #remove newline character  



########################################################
# Sub caschex
#       
# USAGE: Removes hidden strings in variables.. Addition to Clean
#       
# v1.0.0 -> 2006-04-20
# Born  
#       
######  
# my ($item) = cipdec(1, $ip);  #1 = A->H, 2 = H->A                   
+    
######  
#
sub caschex
  {
  # 1 = ASCII TO HEX
  # 2 = HEX TO ASCII

##########
  my $debug = 0;
##########
  if($debug == 1) { print "---------------------------------- ENTERED 
+SUB: \"caschex\"\n"; }

  my $opt = undef; my $item = undef; my $ret = undef; my $val = undef;

  $opt = shift(@_);
  $item = shift(@_);

  if($debug == 1)
    {
    print "\n\n";
    print "OPT: \"$opt\"\n";
    print "ITEM: \"$item\"\n";
    }

  ############################# OPT 1
  if($opt == 1)
    {
    if($debug == 1) { print "CONVERT ASCII TO HEX\n"; }

    $key = undef; $val = undef;
    foreach $key (split//,$item)
      {
      if($debug == 1) { print "KEY: \"$key\"\n"; }
      ($key) = sprintf("%02lx", ord $key);
      if($debug == 1) { print "HEX KEY: \"$key\"\n"; }

      if(($key eq "00") || ($key eq "1b"))
        {
        if($debug == 1) { print "FOUND NULL IN ASCII VARIABLE... REPLA
+CE WITH SPACE\n"; } 
        $key = " ";
        #NOTE: A SPACE IN HEX IS "20"
        ($key) = sprintf("%02lx", ord $key);
        if($debug == 1) { print "HEX KEY: \"$key\"\n"; }
        }

      $val .= $key;
      if($debug == 1) { print "VAL: \"$val\"\n"; }
      }

    if($debug == 1) { print "COMPLETE VAL: \"$val\"\n"; }
    }
  ############################# EO OPT 1

  ############################# OPT 2
  if($opt == 2)
    {
    if($debug == 1) { print "CONVERT HEX TO ASCII\n"; }

    $key = undef; $val = undef;
    foreach $key ($item =~ /[a-fA-F0-9]{2}/g)
      {
      if($debug == 1) { print "HEX KEY: \"$key\"\n"; }

      if(($key eq "00") || ($key eq "1b"))
        {
        if($debug == 1) { print "FOUND NULL IN HEX.. REPLACE WITH SPAC
+E\n"; } 
        $key = 20;
        if($debug == 1) { print "HEX KEY: \"$key\"\n"; }
        }

      ($key) = chr(hex $key);

      if($debug == 1) { print "ASC KEY: \"$key\"\n"; }
      $val .= $key;

      if($debug == 1) { print "VAL: \"$val\"\n"; }
      }
    if($debug == 1) { print "COMPLETE VAL: \"$val\"\n"; }
    }
  ############################# EO OPT 2

  
  $ret = $val;
  
  if($debug == 1) { print "RET: \"$ret\"\n"; }
  if($debug == 1) { print "---------------------------------- LEAVING 
+SUB: \"caschex\"\n"; }
  
  $debug = 0;
  return($ret);
  }
#
#
############################################## EO SUB CASCHEX
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