This is a seperate question from my Matching An IP Address post, but it is related.

I am looking at data of the type:

 136.1.1.154:33672 ->  64.210.209.51:80 ->  192.168.1.145:80          
+  tcp
 65.201.211.176:14664 ->  64.210.209.54:80 ->   192.168.1.78:80       
+     tcp
    67.38.95.86:2116 ->  64.210.209.50:80 ->  192.168.1.103:80        
+    tcp
 198.49.222.246:52469 ->  64.210.209.54:80 ->   192.168.1.79:80       
+     tcp
 193.80.106.152:3781 ->  64.210.209.61:80 ->   192.168.1.81:80        
+    tcp
    67.28.79.24:3248 ->  64.210.209.54:80 ->   192.168.1.79:80        
+    tcp
 128.187.192.39:1218 ->  64.210.209.54:80 ->   192.168.1.78:80        
+    tcp
 128.187.192.39:1209 ->  64.210.209.51:80 ->  192.168.1.144:80        
+    tcp

[download]

The regex another user suggested was 
my $re_ip = qr/(\d+\.\d+\.\d+\.\d+):\d+/;
my $re_line = qr/ ^ \s* $re_ip \s* -> \s* $re_ip \s* -> \s* $re_ip /x;

[download]

However, I have found this does not work. It is the $re_line which is the culprit.

The following patterns DO work:
qr/^\s*$re_ip\s*->\s*$re_ip\s*->\s*$re_ip/

qr/^ \s* $re_ip\s*->\s*$re_ip\s*->\s*$re_ip/x

qr/^\s*$re_ip\s*-> \s* $re_ip\s*-> \s* $re_ip/x

qr/ ^ \s* $re_ip\s*->\s*$re_ip\s*->\s*$re_ip/x

[download]

The following do NOT work:
qr/ ^ \s* $re_ip \s*->\s*$re_ip\s*->\s*$re_ip/x

qr/ ^ \s* $re_ip\s*->\s*$re_ip \s*->\s*$re_ip/x

[download]

Based on this, I think it is the space between a $re_ip and a \s* that is the culprit.

Can anyone explain why? I thought /x was supposed to allow whitespace within a regex.

Thanks.


<-> In general, we find that those who disparage a given operating system, language, or philosophy have never had to use it in pratice. <->

In reply to Matching IP address continued by ibanix

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