Re: how to make a regex for a ip address

[Connie Chan]

Emmm... So do you want to do it in 1 line or your just want to try
on ? For me, it seems quite non-effective & impossible with one line... 
but breaking them into pieces, that becomes handy. I use this :

my $ip = $ENV{REMOTE_ADDR}; 
my $error = 0;
my @seg = split /\./, $ip; 

$error = 1 unless ($#seg ==3); 
    # or (scalar(@seg)== 4), this check Format error

foreach my $num(@seg) # Checking on each segment
 {
   $error = 1 if ($num < 0 or $num > 255 or $num =~ /[^\d]/) 
        # first 2 condition checking the range.
        # =~ /[^\d]/ means, if found any non digit char.
 }

print $error;

# basically like this, but, perhaps you don't want some subnet 
# mask or localhost or local lan ips... so you can continue
# like this :

$error = 1 if ($ip =~ /^0|255|192|127\..+$/);
# And you can add up some more  ...

Refer to some existed modules may much helpful too.

Rgds,
Connie


----- Original Message ----- 
From: "alex chen" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Sunday, August 18, 2002 11:14 PM
Subject: how to make a regex for a ip address


> hi,
>   i am a beginners in perl.i am studying perl regex now ,and i want to know
> how to make a regex for a ip address.
> 
>   thank you!!
> 
> 
> 
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