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如果碰上一些MP4中的音乐特别好听的，想转成MP3的话怎么办？

用ffmpeg就可以实现：

ffmpeg -i a.mp4 b.mp3

还可以加 -b:a 192k 来指定码率

更多参数可参照：https://trac.ffmpeg.org/wiki/Encode/MP3

 

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1) If RRAS based VPN server is behind a firewall (i.e. a firewall is placed between Internet and RRAS server), then following ports need to be opened (bidirectional) on this firewall to allow VPN traffic to pass through: –

  • For PPTP:
    • IP Protocol=TCP, TCP Port number=1723   <- Used by PPTP control path
    • IP Protocol=GRE (value 47)   <- Used by PPTP data path
  • For L2TP:
    • IP Protocol Type=UDP, UDP Port Number=500    <- Used by IKEv1 (IPSec control path)
    • IP Protocol Type=UDP, UDP Port Number=4500   <- Used by IKEv1 (IPSec control path)
    • IP Protocol Type=ESP (value 50)   <- Used by IPSec data path
  • For SSTP:
    • IP Protocol=TCP, TCP Port number=443   <- Used by SSTP control and data path
  • For IKEv2:
    • IP Protocol Type=UDP, UDP Port Number=500    <- Used by IKEv2 (IPSec control path)
    • IP Protocol Type=UDP, UDP Port Number=4500   <- Used by IKEv2 (IPSec control path)
    • IP Protocol Type=ESP (value 50)   <- Used by IPSec data path

2) If RRAS server is directly connected to Internet, then you need to protect RRAS server from the Internet side (i.e. only allow access to the services on the public interface that isaccessible from the Internet side). This can be done using RRAS static filters or running Windows Firewall on the public interface (or the interface towards the Internet side). In this scenario following ports need to be opened (bidirectional) on RRAS box to allow VPN traffic to pass through

    • For PPTP:
      • IP Protocol=TCP, TCP Port number=1723  <- Used by PPTP control path
      • IP Protocol=GRE (value 47)  <- Used by PPTP data path
    • For L2TP:
      • IP Protocol Type=UDP, UDP Port Number=500   <- Used by IKEv1 (IPSec control path)
      • IP Protocol Type=UDP, UDP Port Number=4500 <- Used by IKEv1 (IPSec control path)
      • IP Protocol Type=UDP, UDP Port Number=1701  <- Used by L2TP control/data path
      • IP Protocol Type=50  <- Used by data path (ESP)
  • For SSTP:
  • IP Protocol=TCP, TCP Port number=443   <- Used by SSTP control and data path
  • For IKEv2:
  • IP Protocol Type=UDP, UDP Port Number=500   <- Used by IKEv2 (IPSec control path)
  • IP Protocol Type=UDP, UDP Port Number=4500 <- Used by IKEv2 (IPSec control path)
  • IP Protocol Type=UDP, UDP Port Number=1701  <- Used by L2TP control/data path
  • IP Protocol Type=50 <- Used by data path (ESP)

Note: Please DO NOT configure RRAS static filters if you are running on the same server RRAS based NAT router functionality. This is because RRAS static filters are stateless and NAT translation requires a stateful edge firewall like ISA firewall.

Do not forget: If you enable Windows firewall or RRAS static filters on the public interface and only enable VPN traffic to pass-through, then all the other traffic may be dropped. For example, if the same server is running as a mail server facing internet or a DNS server or a reverse web proxy server, then you need to enable the ports used by those services explicitly. For further details, refer to this article: http://blogs.technet.com/rrasblog/archive/2006/07/06/enabling-rras-drops-all-other-traffic-except-vpn-traffic.aspx

Ref: https://blogs.technet.microsoft.com/rrasblog/2006/06/14/which-ports-to-unblock-for-vpn-traffic-to-pass-through/

另外如果L2TP服务器是在防火墙背后的话，Mac可以连，但是Win连不了。这个时候需要改Win的注册表：

Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\PolicyAgent]
"AssumeUDPEncapsulationContextOnSendRule"=dword:00000002

Ref : http://support.microsoft.com/kb/926179

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Ubuntu好像自12.04以后，就把定制的dnsmasq用作自己的DNS解析服务。只绑定在127.0.0.1上面。

但是当你安装了完整版的dnsmasq以后，却发现这个定制版的dnsmasq导致无法在127.0.0.1以外的IP上提供服务。

经过多方研究，发现经过如下两步操作以后，dnsmasq的完整版就可以完美运行了。

  1. 编辑 /etc/NetworkManager/NetworkManager.conf
    在dns=dnsmasq这一行前面加上#注释掉。
    这样就可以把这个定制版的dnsmasq停掉
  2. 编辑/lib/systemd/system/dnsmasq.service
    在[Unit]下面加上这两行：

    After=network-online.target
Wants=network-online.target

    这样的目的是防止dnsmasq先于网卡前启动，导致网卡绑定失败。从而需要每次手工重启dnsmasq服务。

好了。难者不会，会者不难。这样就可以完美解决Ubuntu下面安装试用dnsmasq的问题。

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手上好多个EMax12A的电调，老是感觉不顺手。研究了一下发现有办法可刷BLHeli的固件，好消息。说动手就动手。

首先下载BLHeli Suite -> https://www.mediafire.com/folder/dx6kfaasyo24l/BLHeliSuite

然后拿出Arduino UNO接上电脑，打开BLHeli的Make interfaces功能。

  1. 选择你的Arduino板的型号，这里我选Uno。
  2. 点击ArduinoISP Programmer开始制作Arduino版的电调编程器

blhelisuitemake-interfaces_161108_2

继续阅读

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最近在Ubuntu 16.04上实现了使用XRDP远程连接Unity桌面。这样的话使用Win自带的RemoteDesktop就可以连接Ubuntu的Unity了。

下面把步骤写下~

  1. 下载并安装TigerVNC
    下载：https://bintray.com/tigervnc/stable/tigervnc/1.7.0#files/ubuntu-16.04LT
    安装：sudo dpkg -i tigervncserver_1.7.0_xxx.deb
    安装的时候可能会提示缺包，这时候用命令sudo apt-get install -f补全。
  2. 安装XRDP
    sudo apt-get install xrdp
  3. 配置XRDP
    单用户执行：echo unity>~/.xsession
    多用户执行：sudo sed -i.bak ‘/fi/a #xrdp multi-users \n unity \n’ /etc/xrdp/startwm.sh

OK！搞定！就这三步就可以实现XRDP连接Ubuntu Unity。怎样？简单吧？

不过这个方法也是bug的，目前已知的bug是：

  1. 鼠标指针丢失
    修复方法也比较简单，在桌面上右键打开Terminal就可以解决
  2. Indicator Panel丢失
    没有这个Panel，你就不能Logout等等了。而且这个问题目前暂时没有解决方案。

参考URL：http://c-nergy.be/blog/?p=9962

 

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大疆精灵3和大疆悟的图传都只有8个默认通道，有时候会因为受到外界干扰飞行的时候图传中断，是个很蛋疼的事情。可能有些模友还不知道，其实Phantom3的图传通道还是可以破解的，inspire 1理论上也可行，因为图传用的是同一套方案。

破解方法非常简单，安卓就是把附件里面的这个.DJI.configs文件释放到 \Android\data\dji.pilot\files

iOS的话就是直接把这个.DJI.configs文件放到APP目录下面。

搞定以后打开DJI GO，就会发现图传已经可以选择32通道了。但是注意只能选手动指定通道，不能选择自动。

破解32信道以后，只要有遥控信号的时候，图传就不会消失。不然有些地方干扰大了，会造成图传卡顿，或者消失，但遥控信号依然受控。

Screenshot_2016-09-01-01-02-21-783_dji.pilot

下载：32channel

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已经可以Ping通Google.com或者Google.com.hk了。但是怎么还是不能打开？ 原来是跳回到http了。

要强制https的话，以Chrome为例。可以打开 chrome://net-internals/#hsts

在 Domain 栏里，输入 google.com或者google.com.hk，并勾选下面的两个复选框，点击 “Add” 按钮即可。

强制 Google 网页快照使用 HTTPS，输入 googleusercontent.com。

强制 Google APIs 使用 HTTPS，输入 googleapis.com。

hsts

当然如果你嫌这个操作比较繁琐的话，可以安装插件HTTPS Everywhere。

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1、查看系统

[root@localhost ~]# cat /etc/issue
CentOS release 6.6 (Final)
[root@localhost ~]# uname -a
Linux localhost.localdomain 2.6.32-042stab106.6 #1 SMP Mon Apr 20 14:48:47 MSK 2015 x86_64 x86_64 x86_64 GNU/Linux

2、安装ShadowSocks

# yum install python-setuptools && easy_install pip
# pip install shadowsocks

3、创建配置文件/etc/shadowsocks.json

[root@localhost /]# touch /etc/shadowsocks.json
[root@localhost /]# vi /etc/shadowsocks.json
{
"server":"138.128.208.158",
"server_port":443,
"local_address": "127.0.0.1",
"local_port":1080,
"password":"MyPass",
"timeout":300,
"method":"rc4-md5"
}

备注：加密方式官方默认使用aes-256-cfb，推荐使用rc4-md5，因为 RC4比AES速度快好几倍。继续阅读

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LINUX

netstat -lntu

as replied by @askmish will give you list of services running on your system on tcp and udp ports where

  • -l = only services which are listening on some port
  • -n = show port number, don’t try to resolve the service name
  • -t = tcp ports
  • -u = udp ports
  • -p = name of the program

You don’t need the ‘p’ parameter as you’re only interested in getting which ports are free and not which program is running on it.

This only shows which ports on your system are used up, though. This doesn’t tell you the status of your network e.g. if you’re behind NAT and you want some services to be accessible from outside. Or if the firewall is blocking the port for outside visitors. In that case, nmap comes to the rescue. WARNING: Use nmap only on networks which are under your control. Also, there are firewall rules which can block nmap pings, you’ll have to fiddle around with options to get correct results.

2016.09.27 更新
netstat -peanut 用这个参数更可以列出是哪个程序在占用哪个端口

Windows

netstat -ano 可以直接列出PID，然后到任务管理器里面可以根据PID查看是哪个程序。