This blog article records the progress of setting up IPv6 tunnel to Hurricane Electric at home where my ISP has no plan in sight to provide prefix-delegated IPv6 access over a PPPoE.
Shorthands and Assumptions in This Note
eth0connects to the Internet via IPv4. This note shall also apply to encapsulated interfaces, e.g.
eth1connects to local LAN. Similar as above, the process shall be the same when LAN side is a VLAN or bridge (or both).
sittunnel interface created in this step.
- A line beginning with
#denotes comments in the configuration notes.
Setting up the Tunnel Interface on ER-X
If registered correctly on TunnelBroker, it should provide the following information:
- Logical address at local endpoint, e.g.
- Logical address at remote endpoint, e.g.
- IPv4 address at remote endpoint where encapsulated traffic is sent, e.g.
126.96.36.199, the HE tunneling endpoint in Paris.
- A routable prefix for client side delegation, e.g.
2001:444:112:222::/64. This is usually different from the v6 addresses for the endpoint, and HE will show segments of the prefix in bold.
Now fill ER-X configuration nodes with corresponding information and default routing for IPv6:
interfaces: tunnel: tun0: address: [Fill logical v6 address in CIDR at endpoint] description: [Give a name to this tun] encapsulation: sit local-ip: [Fill in IPv4 address at eth0] remote-ip: [Fill in IPv4 address at tunneling endpoint] protocols: static: interface-route6: ::/0: next-hop-interface: tun0 # This creates a default IPv6 routing table entry that # routes all non-link-local address to the tunnel.
At this point, one should be able to ping any IPv6 address from the ER-X. If this is working, continue to instruct the LAN interface to delegate the prefix
interface: <path-to-interface-config-node>: ipv6: dup-addr-detect-transmits: 1 # Stateless SLAAC configuration might produce identical # IP addresses. This allow the network to detect whether # a stateless address already exists. address: autoconf # Set autoconf to allow stateless delegation by SLAAC router-advert: prefix: [Fill routable delegated prefix here]: autonomous-flag: true # Instructs computers on this network to auto # discover DNS servers on-link-flag: true # Indicates that this prefix exists on the # same Ethernet link, i.e. these addresses # does not require routing
IPv6 enabled devices shall now receive globally unique IPv6 address assigned via SLAAC and prefix delegation.
- Confirm IPv6 assignment on LAN devices
$ ip addr <------ MORE INTERFACES REDACTED ------> 2: eno1: mtu 1480 qdisc fq_codel state UP group default qlen 1000 link/ether XX:XX:XX:XX:XX:XX brd ff:ff:ff:ff:ff:ff inet 192.168.5.4/24 brd 192.168.5.255 scope global dynamic noprefixroute eno1 valid_lft 80444sec preferred_lft 80444sec inet6 2001:470:d:XXXX:XXXX:XXXX:XXXX:dfd3/64 scope global dynamic noprefixroute valid_lft 2591976sec preferred_lft 86376sec inet6 fe80::be40:XXXX:XXXX:XXXX/64 scope link noprefixroute valid_lft forever preferred_lft forever <------ MORE INTERFACES REDACTED ------>
- Trace IPv6 connections to an IPv6 enabled website
$ traceroute -6 ac.cth451.me -n traceroute to ac.cth451.me (2606:4700:30::681c:1b16), 30 hops max, 80 byte packets 1 2001:470:d:XXXX:XXXX:XXXX:XXXX:XXXX 0.415 ms 0.533 ms 0.624 ms 2 2001:470:c:XXXX::1 185.353 ms * 203.802 ms 3 2001:470:0:9d::1 178.603 ms 167.001 ms 189.255 ms 4 2001:504:0:3:0:1:3335:1 196.520 ms 179.737 ms 196.117 ms 5 2400:cb00:12:1024::6ca2:d61d 185.036 ms 2400:cb00:12:1024::6ca2:d614 175.573 ms 2400:cb00:12:1024::6ca2:d608 185.263 ms
- It is advisable to setup network wide firewall on the router, as addresses can be reached by any other IPv6 connected devices from the Internet.
sittunnel shall also work if setup correctly on any other router or even a personal computer with public IPv4 address. I am unable to replicate the settings on a Linux router via raw commands as I do not own a linux machine with public IPv4 address.
- I am not sure if the method would work if the local endpoint is behind NAT. This scenario will be experimented on after I return to campus.
The story begins with the moment I bought Cytus II on the very first day of its release from google play, expecting some real music gaming on my Surface Pro 3 running homebrew Android 7.1 (yes, that’s totally possible and it runs suprisingly fine with all hardware buttons and touchscreen working). However the game quits immediately and no logs are shown through the adb interface. I contacted Rayark for support and got reply like this:
Cytus II might only be compatible for native Android devices at the moment. Please also check if you have installed Xposed, firewalls, block ads, or any rooting software. If yes, these may effect the performance of the game. We’d like to suggest you to remove these software to ensure the game runs smoothly and properly.
(Probably) 3 weeks after the game’s release, I ended up playing Cytus II on my crammed 5′ mobile phone, not by choice though. Someone asked me, why I can’t buy a regular Android tablet or an iPad to do the same job. Well that could be an option if those people would donate in any means for a new one, and I really don’t think utilizing an existing hardware piece could cause any troubles for commercial devs and companies (Google: really?).
After some searches I reached conclusion that Cytus II has integrated an “compliance check” called SafetyNet and the underlying Compatibility Test Suite (CTS), a framework introduced by Google to verify if any android device falls into the category of “compatible”. Since Surface Pro 3 has never got an official Android release (it’s a Microsoft thing, of course) and the base android x86 is shipped with root and development mode on, there is probably no way that any CTS tests on Surface Pro 3 would pass any time sooner.
Just earlier this day, I saw the news that Google is attmpting to block Gapps from running on “uncertified” devices, where modding the android device or unlocking bootloader would void the “certified” status. There’s even a webpage letting people to “register” their Androids with their device identifier which is absolutely not working after I attempted to register my Surface only getting an unknown error.
I would not blame Rayark for their attempt to place a layer of piracy protection on such a nice game while hurting the ones who modded their devices properly exactly to play these games. My question is: If such a lockdown is so important that this system had been deployed to thousands of android software by now, why make android an open standard? Why not switch to the Apple production mode if a centralized control force seems so vital to the whole android community? Such blockage wouldn’t be easily tolerated if the so called “register uncertified devide page” is just a lie, and I believe there will be a solution to circumvent such unreasonable restrictions eventually. Before that, the vast population of “uncertified” androids and modders wouldn’t be so comfortable and I might really need to ask myself: Why I should spend 3 months porting an open source OS to a new device just to find nothing should works by design.
When I told someone Chengdu is a hot city, I meant both food and the city itself. Hopefully, I finally remembered that I forgot
procrastinated to post my photos I took when I travelled to Chengdu and stayed for a few days this winter. Still, these pictures are taken from my old Canon 50D DSLR and the mediocre lens.
It’s -30 degree celcius in Madison. It’s snowing. It’s the season of white album again.
Camera: Canon EOS 50D (a really old DSLR)
Lens: Canon EF-S 17-85mm f4-5.6 IS USM (yes, the very mediocre default)
Location: In my room [precise location redacted]
After windows upgrading itself to release 1703 aka. the creator update, Grub bootloader can no longer start and says
error: unknown filesystem and dropped in to grub rescue shell. Windows boots up fine from firmware memu.
Manually doing hexediting just taught me another valuable lesson: @Windows has the worst upgrade handling.
— @cth451 July 28, 2017
- Prepare a USB linux live environment.
- Find the correct partition number, it might have been changed during upgrade.
- Look for
grubx64.efiin your EFI system partition and use a hex editor to open it
- Search for
/boot/gruband notice the
(,gptN)where N is your original partition number for linux OS.
- Change N to the new parition number, save the file and reboot.
Before upgrade, my partition scheme was:
- sda1 fat32: EFI system parition
- sda2 ext4: Archlinux root filesystem
- sda4 ntfs: Windows drive C
- sda3 ext4: AOSC OS root filesystem
Partition numbers were not exactly in physical order of data, for I shrinked Archlinux to make room for Windows installation. However after upgrade, it became:
- sda1 fat32: EFI system parition
- sda2 ext4: Archlinux root filesystem
- sda3: Windows drive C
- sda4: Windows recovery environment
- sda5: AOSC OS root filesystem
So what did windows do down there? It shrinked drive C and made a little recovery partition, then re-sorted the partition numbers. However grub bootloader looks for partitions by partition number. It tried parition 3 (which was a valid linux filesystem), but it’s an ntfs now.
Okay found a hardcoded partition number in grubx64.efi… Attempting manual edit… pic.twitter.com/Cww8706Xp8
— @cth451 July 28, 2017
This partition number is hardcoded into the bootloader efi image, so we need to manually hexedit it.
Lake Superior – Sugarloaf Cove
Position: 47°29’11″N 90°58’59″W
I took this photo with the waterproof Xperia upside down with camera underwater. Not exactly what I expected but still amazing enough to see colorful cobblestone underwater.
Yet another regular collection of colorful stone beach.
Lake Mille Lacs
Position: 46°10’52″N 93°43’42″W
This one is pretty off-road on the side of a trail beyond Indians point. Cold, but beautiful.
Minnesota Route 1
Unfortunately I lost Geo-tag in this photo… So I don’t know the precise location on the road.
This would be one of my last frames of Minecraft renderworks with chunky. I will be switching to blender, an open source modeling software that supports GPU ray tracing with CUDA and allows tweaks to model before performing actual (now night-long) rendering.
Chunky is still pretty straightforward to newbie CG makers, written in java that virtually runs everywhere, but it does not support GPU rendering, and java multi-threading overhead made it even worse.
Blender, on the other hand, needs a few hours to setup but provides far more precise control over elements, vertices, edges and fancy stuff. Cropping down map portions out of the camera view, customize torch light color, removing specific blocks, render entities with actual motion…
So… Goodbye, chunky. Hi, Blender!
I might still recommend chunky for those who want to have a sip of minecraft rendering, but for more complex terrain and huge creations, use blender.
Here’s the downscaled rendered frame, but you can still find full resolution on deviant art.
Rendering time: 1.57 days
Original dimensions: 4000x4000
Downscaled dimensions for uploading: 2000x2000
[-52.42685239911796, 88.92741372864917, -249.4581397458882, Midymidy/CREATIVE]
# Sample Per Pixel: 5000
Render Time: 31574166 milliseconds