Ever think of IP address 137.82.2.215 in internal can be written as 2303853271 in base 10. 137 = 0x89 82 = 0x52 2 = 0x2 215 = 0xD7, put them together is 0x895202D7 in base 16, and perl -e 'print hex '\x895202D7', "\n" ' will be 2303853271 in base 10. Apache1.3.* seems still accept http://2303853271 as legitimate request, Apache2 seems don't accept http://2303853271 as legitimate request.

The octal numeral system is the base-8 number system, and uses the digits 0 to 7.

Octal numerals can be made from binary numerals by grouping consecutive digits into groups of three (starting from the right). For example, the binary representation for decimal 74 is 1001010, which groups into 1 001 010 — so the octal representation is 112. see more detailes at http://en.wikipedia.org/wiki/Octal

In computer technology and networking, an octet is a group of 8 bits. see http://en.wikipedia.org/wiki/Octet_%28computing%29

The email spam filter hasn't been running for a while on the email server. Today, I finally upgraded all the component, and tested working fine

There is spamassassin rule lint info after upgrading from 3.1.1 to 3.1.4, if running spamassassin -Dinfo --lint on command line, you will see info line like :

[24649] info: rules: meta test COMBO_IMAGEONLY1 has dependency 'MIME_HTML_ONLY_MULTI' with a zero score
[24649] info: rules: meta test MR_MULT_REF has undefined dependency 'nice'
[24649] info: rules: meta test SARE_MULT_RATW_03 has undefined dependency '__SARE_MULT_RATW_03E'

you can see more info from http://issues.apache.org/SpamAssassin/s ... i?id=4347.

#diff -Nuar ./Mail-SpamAssassin-3.1.1/lib/Mail/SpamAssassin/PerMsgStatus.pm ./Mail-SpamAssassin-3.1.4/lib/Mail/SpamAssassin/PerMsgStatus.pm

--- ./Mail-SpamAssassin-3.1.1/lib/Mail/SpamAssassin/PerMsgStatus.pm 2006-03-10 11:29:55.000000000 -0800
+++ ./Mail-SpamAssassin-3.1.4/lib/Mail/SpamAssassin/PerMsgStatus.pm 2006-07-25 15:02:19.000000000 -0700

@@ -2455,6 +2482,13 @@
$meta{$rulename} .= "$self->{'tests_already_hit'}->{'$token'} ";
$setup_rules{$token}=1;

+ if (!exists $self->{conf}->{scores}->{$token}) {
+ info("rules: meta test $rulename has undefined dependency '$token'");
+ }
+ elsif ($self->{conf}->{scores}->{$token} == 0) {
+ info("rules: meta test $rulename has dependency '$token' with a zero score");
+ }
+
# If the token is another meta rule, add it as a dependency
push (@{ $rule_deps{$rulename} }, $token)
if (exists $self->{conf}{meta_tests}->{$priority}->{$token});

Quote from felicity

" the rules would likely have had these issues for a while (I can't
really comment on non-official rules), but with 3.1.4 there's now info output
showing that there's a problem. (before, people would have had to manually
figure out that meta dependencies have issues)
"

No worry then :)

From the perldoc DESCRIPTION section of DnsResolver.pm, it says :" This is a DNS resolution engine for SpamAssassin, implemented in order to reduce file descriptor usage by Net::DNS and avoid a response collision bug in that module.", what this description really refered to is bugs:

http://issues.apache.org/SpamAssassin/s ... gi?id=3997
http://issues.apache.org/SpamAssassin/s ... gi?id=4260

bug 3997 is really a long discussion, comment #73 finally sort out what the cause is

------quote-----
"....The problem is that there is nothing in the RFCs to prevent reuse of a UDP
source port once there is no active listener on that port. UDP connections are
not persistent, so there is nothing that IO::Socket can do to ensure that a
reply to a UDP port is not a response to some old packet that was sent from that
port.


This is a known problem in the DNS world, with a solution built in to the DNS
protocol. The DNS query packet has a header with an identifier field, which is
an arbitrary 16 bit number set by the sender. The nameserver copies it to the
identifier field of the header of the response packet. see http://www.tcpipguide.com/free/t_DNSMes ... #Table_169

This is above the IO::Socket layer, so the fix can't be there. Net::DNS can't
use the ID field to ensure that a bgread matches up with a bgsend unless it
cached every socket returned by bgsend in order to save the ID in a hash with
it. I don't think that is practical.

That leaves SpamAssassin as the right level for the fix.

---------quote-------------