Windows XP and IPv6

I am helping an organization to write a 40-page consumer guide on IPv6.  One sub-section deals with IPv6 in Windows XP and its limitations. This is what I have come up with today.


"While IPv6 functionality is present in Windows XP, it is not suitable for use in a corporate network environment. The following limitations are found in Windows XP in support of IPv6:

1.  There is no graphical user interface for address assignment and these tasks must be performed at command line.

2.     There is no DHCPv6 client in Windows XP. An IPv6 router can only use Stateless Address Autoconfiguration (SLAAC) to assign address to a Windows XP PC.

3.     Privacy protection mechanism in address assignment through SLAAC is not enabled by default. Activity tracking based on the IPv6 address is possible

4.     The personal firewall of Windows XP is broken when IPv6 is installed. When a port is open in IPv4, the same port is also open in IPv6.

5.     Windows XP can not have name resolution over IPv6. Some websites will not be accessible by Windows XP if the domain names of the websites are hosted in IPv6 only name servers."

After reading the above, I doubt people still want to use IPv6 in Windows XP.  

v4 SMTP server can send out v6 outgoing email

Some friends asked me the myth about my SMTP server running on IPv4 can send out IPv6 emails to dual-stack SMTP servers.   There is no secret. My SMTP Server does not bind to any specific IP address so it just listen and use all available addresses in the Network Interface Card, both v4 and v6.  In sending email to a dual-stack mail server, v6 path is logically selected first.  However, I can not receive incoming emails from v6 path due to the lack of a MX record pointing to a v6 host.  Interesting stuff !!

Our IPv6 SMTP Server in service

OFCA IPv6 SMTP Server was successfully configured. The most difficult part was to ask the ISP to do the reverse v6 lookup matching to the host of MX record.  I did not touch the server work.  I just gave technical advice and everything worked to my satisfaction.


May 23 22:57:46 i3way sendmail[19437]: q4NEvMol019435: to=, ctladdr= (500/500), delay=00:00:24, xdelay=00:00:24, mailer=esmtp, pri=120315, relay=mail.ofca.gov.hk. [IPv6:2001:218:6009:2::51], dsn=2.0.0, stat=Sent (q4NEvSjc011727 Message accepted for delivery)
May 23 22:57:46 i3way sendmail[19437]: q4NEvMol019435: to=, ctladdr= (500/500), delay=00:00:24, xdelay=00:00:24, mailer=esmtp, pri=120315, relay=mail.ofca.gov.hk. [IPv6:2001:218:6009:2::51], dsn=2.0.0, stat=Sent (q4NEvSjc011727 Message accepted for delivery)
May 23 22:52:48 i3way sendmail[19378]: q4NEqO8V019376: to=,, ctladdr= (500/500), delay=00:00:24, xdelay=00:00:24, mailer=esmtp, pri=151351, relay=mail.ofca.gov.hk. [IPv6:2001:218:6009:2::51], dsn=2.0.0, stat=Sent (q4NEqePi011717 Message accepted for delivery)
May 23 22:57:46 i3way sendmail[19437]: q4NEvMol019435: to=, ctladdr= (500/500), delay=00:00:24, xdelay=00:00:24, mailer=esmtp, pri=120315, relay=mail.ofca.gov.hk. [IPv6:2001:218:6009:2::51], dsn=2.0.0, stat=Sent (q4NEvSjc011727 Message accepted for delivery)

Staying Alive

Staying Alive - that's the promise of Robin Gibb, but he did not keep his promise. He left us. He meets Maurice and Andy now in another place, another world. 


I was listening to his songs with my ipod this morning without knowing the sad news.  The name "Bee Gees" is always staying alive in my mind and my heart. 


To all with a broken heart, how can you mend a broken group ? 

Facebook Phishing

I've got quite a number of phishing email pretending from Facebook.  The tactic is old and easily detected. The messages said I have some friend requests and asked me to click a link.  In another message, it asked me to confirm email address by clicking a page in order to associate with my Facebook account.  These tricks are obvious and the links will re-direct me to malware websites.

Email honeypot HD storage problem

One of my friends has successfully set up an email honeypot acting as an open relay decoy.  Spammers successfully seize the host and deposit spam messages. The email honeypot just does not deliver any messages but store up on a daily basis. Then comes a difficulty.  A spam message has thousands of recipients and each spam message to a recipient consisting of the mail header part and message part (2 files) resulting in many millions of new files created a day which eat up several Gbytes of HD storage.  I recalled that I resolved this problem many years ago.  In sendmail.cf or sendmail.mc, there is an option to limit the number of recipients in a message.  I rather like to edit sendmail.cf directly by adding these 2 lines:

# maximum number of recipients per SMTP envelope 
O MaxRecipientsPerMessage=10 

This should work fine as I am quite sure I have tried this many many times before.