IPv6 WiFi in Office

My IT colleagues in OFCA are fantastic and forward-looking. They provide IPv6 connection in all WiFi APs in our office premises.

We have a /48 block which can support 65536 /64 prefixes.  Assuming 20 APs are used, we still have 65516 /64 prefixes remaining for future use.

牙膏一定要用到盡

現在百物騰貴，每支牙膏一定要用到盡，切勿浪費。

Symbolic link to access Dropbox

Just created a symbolic link in Dropbox folder of MAC Book Air. The result is that I can sync and backup other important directories to Dropbox cloud storage without duplicating the directories/files/documents in the default Dropbox folder. Save a lot of hard disk space and admin tasks. Extremely useful !

陽光 ?

四月至七月，有超過六成半時間是下雨，公園裏給小朋友遊玩的設施都出現發霉和發黑。唉，請給我們多點陽光好嗎?

Teredo tunneling

Please be fair to Microsoft. Teredo is a gift from Microsoft albeit there is no guarantee on the quality of service. The technology behind is highly complicated.

6to4 in WAN connection

This is a difficult question. My IPv6 router supports 6to4 in WAN connection and therefore I can have IPv6 addresses assigned by SLAAC + Stateless DHCP in the LAN side.  Will PCs in the LAN side associated with the router give IPv6 higher priority than IPv4 when accessing dual-stack websites.  My past experience is that for end-point 6to4 address assigned automatically in Windows 7 PCs, the IPv6 connection has a lower priority.  I will find out the answer as soon as possible. 

Why IPv6 only devices fail to access IPv4 applications through DNS64 + NAT64

Oh, I forgot to write why IPv6 only devices fail to access IPv4 applications even the IPv6 service provider has provided DNS64 + NAT 64.  It is because some applications hard code IPv4 addresses instead of domain names.  The remedy by 464XLAT is to have an extra module in devices which converts outgoing IPv4 address to a pseudo IPv6 address (46 translation) and at the service provider change the IPv6 to IPv4 address (64 translation).  Combining the 46 translation and 64 translation together, the name 464XLAT is therefore derived.

It should be noted that there is no need to assign any NAT IPv4 address to a device when using 464XLAT.

As all applications must pass through this module, it could only be implemented at the OS level.  I know Android CLAT is designed with this in mind.

DNS64 + NAT64 + 464XLAT

“DNS64 + NAT64 + 464XLAT” is really genius. All problems of connecting IPv6 only devices to IPv4 applications resolved.  Only an extra CLAT module is needed in smartphones or gateway routers. CLAT handles the translation of ipv4 to ipv6 for applications that do not support dns64. CLAT is needed when transitioning to IPv6 on GSM networks using NAT64 as the IPv4 access method. 

Upgrade IPv4 network to IPv6 network ?

This is written by Huawei in a technical white paper:

“During the upgrade from an IPv4 broadband access network to an IPv6 broadband access network, the addresses of users are upgraded from IPv4 addresses to IPv6 addresses.”

IPv4 and IPv6 networks are incompatible, there can not be any upgrade. Moreover, it gives readers the impression that IPv4 addresses can be upgraded to IPv6 addresses by extending the address space. I want to say “FUCK” to Huawei !

Config IPv6 LAN side

The best configuration I choose for IPv6 LAN side with a routed /64 prefix is SLAAC + DHCPv6 Stateless. I can not use SLAAC + RDNSS as Windows 7 still can not support it. I don’t like DHCPv6 Stateful, no reason for that, just a personal dislike.

I love SLAAC + RDNSS most but can not use it.  

2013 7-1 遊行

今日遊行人士全都表現高質素，他們中午二時起在維園等出發，其間遇上傾盤大雨，便穿上雨衣，拿着雨傘耐心等候個多小時。當轉入怡和街時，警察未能及時開路，又要罰企一小時，天上仍是橫風橫雨掃個不停，此際遊行人士依然十分克制，只大聲要求盡快開路，沒有粗言穢語，炒蝦拆蟹。還有是他們樂意將傳單及膠樽交到大會預設的廢物會收站，不隨地丟棄。民建聯、工聯會，你們的的蛇齋餅糉支持者，永世都無這種質素。