I'm starting to provide Chinese / English versions of some posts, switch with the Language menu above. 我开始提供部分文章的中文、英文翻译,请使用顶部语言菜单切换。

Disabling TR069 on a Youhua PT926G Fiber Optic Modem

This post explains the procedure to disable TR069 on a Youhua PT926G fiber optic modem, to prevent China Telecom from pushing config/firmware updates, and void your changes of switching to bridging mode, or setting port forward rules.In the WAN settings of the management portal of this modem, the TR069 connection can neither be modified or removed. But with a simple patch on the management portal's code, you can break the limitation on the modem.First, you should follow my previous post: Hacking a Youhua PT926G Fiber Optic Modem, to obtain the Telnet Root password.Then Telnet in, run su and type in the password to get to Root Shell. When you do that correctly, the commandline will prompt #.Then follow these steps:Type cp /home/httpd/web/net_eth_links.asp /var/ and hit Enter....

Hacking a Youhua PT926G Fiber Optic Modem

This post explains the prodecure to obtain such privileges from a Youhua PT926G fiber optic modem, without disassembling the device or using serial port converters.Super Admin users on Web UI (telecomadmin)Telnet's root user accessFTP accessFYI I obtained the device from China Telecom, Guangdong Shenzhen.Log on as Super Admin ¶If you directly access the modem's IP (http://192.168.1,1), you will see such a login page to the modem:Here you can login with account name useradmin and the password labeled on the back of the modem, but there's not much you can do one logged in. The only useful thing seems to be Wi-Fi setting.But a nmap scan reveals much more:$ nmap -v 192.168.1....

Remove OpenVPN's Stable-privacy IPv6 Addresses

On my VPSes, the TAP network interface created by OpenVPN has a randomly-generated IPv6 address with scope stable-privacy.This address itself is created randomly to prevent tracking users by their IPv6 addresses. But when building a network in DN42, BGP handshakes may originate from this address (rather than your manually assigned link-local address), and fail for mismatching origin/IP.The solution is to configure the TAP interfaces with sysctl, and disable the automatic address generation options. OpenVPN can be configured to run sysctl automatically when creating the interface:# Add to OpenVPN's config filescript-security 2up "/bin/sh -c '/sbin/sysctl -w net.ipv6.conf.$dev.autoconf=0 && /sbin/sysctl -w net.ipv6.conf.$dev.accept_ra=0 && /sbin/sysctl -w net.ipv6.conf.$dev....

Install/Upgrade to Debian 10 on OpenVZ 6

It's year 2020, why are you still using OpenVZ 6 VPSes?Because they only cost one dollar per year.Since the kernel of OpenVZ 6 is extremely old (Linux 2.6.32), newer systems cannot function normally on an old kernel, so I had to stick to Debian 8 with my previous OpenVZ VPSes.But I found a modified glibc (C language runtime library) that allows running Debian 10 normally on OpenVZ 6.WARNING ¶I don't guarantee that the steps below are suitable for all OpenVZ VPSes, nor do I ensure the safety/integrity of this glibc (I didn't look into its modifications, but speaking of security, the end-of-life OpenVZ 6 is probably the farthest thing from security).Backup your data, since in worst scenarios you need to reinstall the OS.Steps ¶The author only provided DEB packages,...

Disabling Webcams During an Online Course

This post will explain the way to disable your webcam on Windows and Linux, so:On the OS level, prevent you from turning on the webcam by mistake, and live stream your footage of having a meal lying on the bed playing games (NSFW)Prevent certain online lecturing software from secretly turning on the webcam.Windows Procedures ¶Press Win+R combination key to open the Run window, type devmgmt.msc and enter to open the Device Manager. Your camera will be in Image Acquisition Devices category, right click on it to disable it.(The following picture is taken from a Simplified Chinese Windows XP, but the procedure and icons should be similar for Windows 7 and 10.)When you need to use the camera, come back to re-enable it, and then close and reopen your browser or online lecturing software....