Connecting two networks with OpenVPN

I have two routers in two cities, both is connected to the Internet via different ISPs. I wanted to let computers behind both routers to be able to talk to each other directly (without port forwarding and other stuff).

Firstly, I set up a OpenVPN server in p2p mode with static keys, whose IP address is 129.168.20.1, on one router, and a p2p client, whose IP address is 192.168.20.2, on the other router. Below are their configuration files:

p2pserver.conf
-------------------------------
mode p2p
proto udp
port 2333
dev tun
ifconfig 192.168.20.1 192.168.20.2
secret static.key
mssfix 1450
verb 1
log /tmp/p2p.log
keepalive 10 120
persist-tun
persist-key
route 192.168.99.0 255.255.255.0

p2pclient.conf
---------------------------------
mode p2p 
proto udp 
dev tun
remote server's_domain name 2333
ifconfig 192.168.20.2 192.168.20.1
verb 1
secret static.key
keepalive 10 120
log /tmp/p2p.log
mssfix 1450
route 192.168.33.0 255.255.255.0


There is one thing to notice. You should add route of the other end's subnet, so that all traffic to the other subnet will be forwarded through the tun device. To enable forwarding through tun device, you should add firewall rules.

Firstly, add following lines in /etc/config/network

config interface 'p2phome'
option ifname 'tun0'
option _orig_ifname 'tun0'
option _orig_bridge 'false'
option proto 'none'

Then, add the new interface to the lan zone of firewall. And enable forwarding in the lan zone. This can be done with OpenWRT's Web UI.

Auto run VirtualBox VM in background on Fedora 22 with systemd

Recently, I discovered that VirtualBox has a headless mode, where you can run a VM in background. You can start a VM in background with this command,

VBoxManage startvm Win7 --type headless

Win7 is the name of the VM

You can also save the state of a VM with this command,

VBoxManage controlvm Win7 savestate

So, I wrote a systemd service file so as to start and stop the VM automatically.

[Unit]
Description=Vbox for win7
After=network.target multi-user.target vboxdrv.service

[Service]
Type=forking
ExecStart=/usr/bin/VBoxManage startvm Win7 --type headless
ExecStop=/usr/bin/VBoxManage controlvm Win7 savestate
TimeoutSec=60

[Install]
WantedBy=default.target

Put this file as vbox.service in ~/.config/systemd/user/ and use systemctl --user to manage the service.

Python as a tftp server

There is a python package called tftpy which implements a tftp client and server. It's more handy for me to set up a temporary tftp server, compared with Fedora's tftp-server package, which relies on systemd.

In order to listen on port 69, python must be running as root. Then, type these lines in the python interactive shell. 

from tftpy import TftpServer

server = TftpServer("tftproot")

serve.listen()

tftproot is the path to the tftproot directory.

Redshift on Fedora 22

Redshift adjusts the screen's color temperature according to the time. It relieves your eyes when working at night. It's homepage is http://jonls.dk/redshift

To install redshift on Fedora 22, type sudo dnf install redshift in terminal. You may also install redshift-gtk, a GUI front-end for gnome desktop. Then you should enable location service in privacy settings. Also add these lines to /etc/geoclue/geoclue.conf to allow redshift to get location from geoclue.

[redshift]
allowed=true
system=false
users=

Finally, type redshift in terminal, and you should notice the change of the color temperature of your screen. However, the shipped systemd service does not work (redshift starts, but no change of color temperature, quite mysterious.) So I installed redshift-gtk and make it autostart when I login. 

Openconnect Server (ocserv) on Openwrt

I'd like to set up a VPN server on a router running Openwrt. There are several choices, L2TP, PPTP, OpenVPN and openconnect. PPTP is not very secure. L2TP must be used with IPSec for security. While OpenVPN and openconnect are both SSL-VPN. They are easy to configure and adaptive to the restrictions of ISP. Because there is a luci app for openconnect server. It's easier to set up than OpenVPN. I would set up an openconnect server, which operates in pseudo-bridge mode, meaning remote clients are on the same subnet as the computers at home.

Openwrt Synchronized Wifi Hotspot

There are three wireless routers at my home. All run Openwrt. One acts as gateway. The other two are APs. Sometimes, my mother wants to turn off WiFi before sleep. She would power off the gateway router. As a result, all clients will connect to the other two APs, and cannot access the Internet.

I want to make things more elegant. When the two APs detect that the gateway is down, they will turn off their wifi as well, and turn it on when the gateway is online again. Fortunately, the two APs have enough ROM for python. So I need not mess around with shell scripts.

Netgear WNR2000 v4 刷 OpenWrt 和 Gargoyle

最近淘了一个二手的WNR2000，硬件版本v4，使用AR9341单芯片方案，4MB闪存，32MB内存。发现自带固件功能太弱，可玩性不高，故刷Openwrt.

WNR2000是Openwrt支持的硬件，可以参考http://wiki.openwrt.org/toh/netgear/wnr2000，但是这个网页里的信息过时了。telnetenable已经不适用于这台WNR2000。可喜的是电路板上留有TTL焊盘，焊上排针就可以使用。离网络口隔离变压器最远的是GND，然后是RX，TX，波特率是115200。

连接上TTL即可看到终端，官方固件是基于Openwrt改造的，进入终端还有Openwrt的字符画。不过可用的指令很少。