ENH: filter.d/vsftpd anchor internal regex at start

config/filter.d/vsftpd.conf

@@ -14,7 +14,7 @@
 # Values: TEXT
 #
 failregex = vsftpd(?:\(pam_unix\))?(?:\[\d+\])?:.* authentication failure; .* rhost=<HOST>(?:\s+user=\S*)?\s*$
-            \[.+\] FAIL LOGIN: Client "<HOST>"\s*$
+            ^ \[pid \d+\] \[.+\] FAIL LOGIN: Client "<HOST>"\s*$
 
 # Option:  ignoreregex
 # Notes.:  regex to ignore. If this regex matches, the line is ignored.