許A倫的部落格: 4月 2016

2016年4月28日星期四

Raspberry Pi - 無線基地台橋接模式

1. 網路架構圖

          ---------------------------------------------
         |        wlan0          |         eth0        |
       LAN PC               Raspberry Pi             Modem
  IP: 192.168.0.100             br0             IP: 192.168.0.1
  GW: 192.168.0.1

2. 準備一張Edimax EW-7811Un無線網卡wlan0，當作Raspberry Pi的LAN
內建的Ethernet網卡eth0，當作Raspberry Pi的WAN
http://www.edimax.com/edimax/merchandise/merchandise_detail/data/edimax/tw/wireless_adapters_n150/ew-7811un/

3. Raspberry Pi啟動後，確認系統是否有正確抓到無線網卡

$ lsusb
Bus 001 Device 005: ID 3538:0901 Power Quotient International Co., Ltd
Bus 001 Device 004: ID 7392:7811 Edimax Technology Co., Ltd EW-7811Un 802.11n Wireless Adapter [Realtek RTL8188CUS]
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter
Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

4. 安裝hostapd套件，讓無線網卡模擬成Soft AP

$ sudo apt-get install hostapd

由於內建的hostapd不支援此張網卡，需要先移除hostpad程式，但保留相關的設定檔

$ sudo apt-get remove hostapd

5. Edimax EW-7811Un的驅動程式，需要從Realtek官網下載，請選擇RTL8188CUS的Linux版本
首頁 > 下載中心 > 通訊網路 ICs > Wireless LAN ICs > WLAN NIC > IEEE 802.11b/g/n Single-Chip > Software > RTL8188CUS Linux
http://www.realtek.com/downloads/downloadsView.aspx?Langid=2&PNid=21&PFid=48&Level=5&Conn=4&DownTypeID=3&GetDown=false&Downloads=true#2742

透過wget命令，下載原廠無線網卡驅動程式到Raspberry Pi

$ wget http://12244.wpc.azureedge.net/8012244/drivers/rtdrivers/cn/wlan/0001-RTL8188C_8192C_USB_linux_v4.0.2_9000.20130911.zip

6. 安裝hostapd程式

$ unzip 0001-RTL8188C_8192C_USB_linux_v4.0.2_9000.20130911.zip

$ cd RTL8188C_8192C_USB_linux_v4.0.2_9000.20130911/wpa_supplicant_hostapd/

$ tar -zxvf wpa_supplicant_hostapd-0.8_rtw_r7475.20130812.tar.gz

$ cd wpa_supplicant_hostapd-0.8_rtw_r7475.20130812/hostapd

$ make clean && make && sudo make install

將hostapd相關檔案複製到/usr/bin

$ sudo cp /usr/local/bin/hostapd* /usr/sbin

7. 安裝wireless工具

$ cd ../../../wireless_tools

$ tar -zxvf wireless_tools.30.rtl.tar.gz

$ cd wireless_tools.30.rtl

$ make clean && make && sudo make install

8. 建立hostapd設定檔

driver: 無線網卡的驅動程式
ssid: 基地台名稱。
channel: 無線通訊的頻道，從1到11
wpa: 無線網路加密協定，1是WPA，2是WPA2
wpa_passphrase: 無線基地台的密碼。

$ sudo vi /etc/hostapd/hostapd.conf

interface=wlan0
driver=rtl871xdrv
bridge=br0
ssid=pi
channel=6
hw_mode=g
ieee80211n=1
wmm_enabled=1
wpa=2
wpa_passphrase=raspberry
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP
auth_algs=1
macaddr_acl=0

測試hosapd設定檔

$ sudo hostapd -dd /etc/hostapd/hostapd.conf

如沒有出現錯誤，按Ctrl+C停止hostapd，編輯hostapd服務設定檔

$ sudo vi /etc/default/hostapd

# Defaults for hostapd initscript
#
# See /usr/share/doc/hostapd/README.Debian for information about alternative
# methods of managing hostapd.
#
# Uncomment and set DAEMON_CONF to the absolute path of a hostapd configuration
# file and hostapd will be started during system boot. An example configuration
# file can be found at /usr/share/doc/hostapd/examples/hostapd.conf.gz
#
#DAEMON_CONF=""
DAEMON_CONF="/etc/hostapd/hostapd.conf"

# Additional daemon options to be appended to hostapd command:-
#       -d   show more debug messages (-dd for even more)
#       -K   include key data in debug messages
#       -t   include timestamps in some debug messages
#
# Note that -B (daemon mode) and -P (pidfile) options are automatically
# configured by the init.d script and must not be added to DAEMON_OPTS.
#
#DAEMON_OPTS=""

啟動hostapd服務

$ sudo service hostapd restart

開機時自動啟動hostapd服務

$ sudo update-rc.d hostapd defaults

9. 安裝網路橋接功能套件

$ sudo apt-get -y install bridge-utils

10. 修改無線網卡的設定值，加入橋接功能

$ sudo vi /etc/network/interfaces

# interfaces(5) file used by ifup(8) and ifdown(8)

# Please note that this file is written to be used with dhcpcd
# For static IP, consult /etc/dhcpcd.conf and 'man dhcpcd.conf'

# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto lo
iface lo inet loopback

iface eth0 inet manual

#allow-hotplug wlan0
#iface wlan0 inet manual
#    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

#allow-hotplug wlan1
#iface wlan1 inet manual
#    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

auto br0
iface br0 inet dhcp
bridge_ports eth0 wlan0

11. 重新啟動

$ sudo reboot

12. 重新啟動後，可下brctl橋接命令，確認橋接模式

$ brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.74da3855819b       no              eth0
                                                        wlan0

13. 參考來源
RPI-Wireless-Hotspot
Raspberry Pi 的應用 - Wi-Fi 無線基地台
Raspberry Pi 的實作 - 自動配置 IP 位址資訊的 DHCP Server
敗家學習之旅之樹莓派(Raspberry Pi) Realtek WIFI AP 架設成功心得分享

2016年4月22日星期五

Raspberry Pi - 無線基地台路由模式 hostapd + dnsmasq

1. 網路架構圖

          ---------------------------------------------
         |        wlan0          |         eth0        |
       LAN PC               Raspberry Pi             Modem
  IP: 192.168.1.100    WAN eth0:  192.168.0.100   IP: 192.168.0.1
  GW: 192.168.1.1      LAN wlan0: 192.168.1.1

3. Raspberry Pi啟動後，確認系統是否有正確抓到無線網卡

$ lsusb
Bus 001 Device 005: ID 3538:0901 Power Quotient International Co., Ltd
Bus 001 Device 004: ID 7392:7811 Edimax Technology Co., Ltd EW-7811Un 802.11n Wireless Adapter [Realtek RTL8188CUS]
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter
Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

4. 安裝hostapd套件，讓無線網卡模擬成Soft AP

$ sudo apt-get install hostapd

由於內建的hostapd不支援此張網卡，需要先移除hostpad程式，但保留相關的設定檔

$ sudo apt-get remove hostapd

透過wget命令，下載原廠無線網卡驅動程式到Raspberry Pi

$ wget http://12244.wpc.azureedge.net/8012244/drivers/rtdrivers/cn/wlan/0001-RTL8188C_8192C_USB_linux_v4.0.2_9000.20130911.zip

6. 安裝hostapd程式

$ unzip 0001-RTL8188C_8192C_USB_linux_v4.0.2_9000.20130911.zip

$ cd RTL8188C_8192C_USB_linux_v4.0.2_9000.20130911/wpa_supplicant_hostapd/

$ tar -zxvf wpa_supplicant_hostapd-0.8_rtw_r7475.20130812.tar.gz

$ cd wpa_supplicant_hostapd-0.8_rtw_r7475.20130812/hostapd

$ make clean && make && sudo make install

將hostapd相關檔案複製到/usr/bin

$ sudo cp /usr/local/bin/hostapd* /usr/sbin

7. 安裝wireless工具

$ cd ../../../wireless_tools

$ tar -zxvf wireless_tools.30.rtl.tar.gz

$ cd wireless_tools.30.rtl

$ make clean && make && sudo make install

8. 建立hostapd設定檔

driver: 無線網卡的驅動程式
ssid: 基地台名稱。
channel: 無線通訊的頻道，從1到11
wpa: 無線網路加密協定，1是WPA，2是WPA2
wpa_passphrase: 無線基地台的密碼。

$ sudo vi /etc/hostapd/hostapd.conf

interface=wlan0
driver=rtl871xdrv
bridge=br0
ssid=pi
channel=6
hw_mode=g
ieee80211n=1
wmm_enabled=1
wpa=2
wpa_passphrase=raspberry
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP
auth_algs=1
macaddr_acl=0

測試hosapd設定檔

$ sudo hostapd -dd /etc/hostapd/hostapd.conf

如沒有出現錯誤，按Ctrl+C停止hostapd，編輯hostapd服務設定檔

$ sudo vi /etc/default/hostapd

# Defaults for hostapd initscript
#
# See /usr/share/doc/hostapd/README.Debian for information about alternative
# methods of managing hostapd.
#
# Uncomment and set DAEMON_CONF to the absolute path of a hostapd configuration
# file and hostapd will be started during system boot. An example configuration
# file can be found at /usr/share/doc/hostapd/examples/hostapd.conf.gz
#
#DAEMON_CONF=""
DAEMON_CONF="/etc/hostapd/hostapd.conf"

# Additional daemon options to be appended to hostapd command:-
#       -d   show more debug messages (-dd for even more)
#       -K   include key data in debug messages
#       -t   include timestamps in some debug messages
#
# Note that -B (daemon mode) and -P (pidfile) options are automatically
# configured by the init.d script and must not be added to DAEMON_OPTS.
#
#DAEMON_OPTS=""

啟動hostapd服務

$ sudo service hostapd restart

開機時自動啟動hostapd服務

$ sudo update-rc.d hostapd defaults

9. 修改無線網路卡的設定值，設定一個指定的靜態 IP 位址

$ sudo vi /etc/network/interfaces

# interfaces(5) file used by ifup(8) and ifdown(8)

# Please note that this file is written to be used with dhcpcd
# For static IP, consult /etc/dhcpcd.conf and 'man dhcpcd.conf'

# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto lo
iface lo inet loopback

iface eth0 inet manual

allow-hotplug wlan0
iface wlan0 inet static
address 192.168.1.1
netmask 255.255.255.0

10. 路由模式需要在Raspberry Pi架設dnsmasq

$ sudo apt-get -y install dnsmasq

修改dnsmasq設定檔

$ sudo vi /etc/dnsmasq.conf

# If you want dnsmasq to listen for DHCP and DNS requests only on
# specified interfaces (and the loopback) give the name of the
# interface (eg eth0) here.
# Repeat the line for more than one interface.
#interface=
interface=wlan0


# Uncomment this to enable the integrated DHCP server, you need
# to supply the range of addresses available for lease and optionally
# a lease time. If you have more than one network, you will need to
# repeat this for each network on which you want to supply DHCP
# service.
#dhcp-range=192.168.0.50,192.168.0.150,12h
dhcp-range=192.168.1.100,192.168.1.254,12h

如果想要開機時使用dnsmasq設定，需要修改設定

$ sudo vi /etc/default/dnsmasq

#DOMAIN_SUFFIX=`dnsdomainname`
DNSMASQ_OPTS="--conf-file=/etc/dnsmasq.conf"


# By default search this drop directory for configuration options.
# Libvirt leaves a file here to make the system dnsmasq play nice.
# Comment out this line if you don't want this. The dpkg-* are file
# endings which cause dnsmasq to skip that file. This avoids pulling
# in backups made by dpkg.
#CONFIG_DIR=/etc/dnsmasq.d,.dpkg-dist,.dpkg-old,.dpkg-new

啟動dnsmasq服務

$ sudo service dnsmasq restart

開機時自動啟動dnsmasq服務

$ sudo update-rc.d dnsmasq defaults

11. 啟動IP Forwarding的功能，將net.ipv4.ip_forward=1拿掉註解

$ sudo vi /etc/sysctl.conf

# Uncomment the next line to enable packet forwarding for IPv4
net.ipv4.ip_forward=1

12. 啟用iptables NAT功能

$ sudo iptables -F
$ sudo iptables -F -t nat
$ sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
$ sudo iptables -A FORWARD -i eth0 -o wlan0 -m state --state RELATED,ESTABLISHED -j ACCEPT
$ sudo iptables -A FORWARD -i wlan0 -o eth0 -j ACCEPT

儲存目前iptables設定值

$ sudo bash -c 'iptables-save > /etc/network/iptables'
$ sudo iptables-restore < /etc/network/iptables

設定開機時，讓iptables的規則自動被載入

$ sudo vi /etc/rc.local

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

# Print the IP address
_IP=$(hostname -I) || true
if [ "$_IP" ]; then
  printf "My IP address is %s\n" "$_IP"
fi

sudo iptables-restore < /etc/network/iptables

exit 0

13. 重新啟動

$ sudo reboot

14. 參考來源
RPI-Wireless-Hotspot
Raspberry Pi 的應用 - Wi-Fi 無線基地台
Raspberry Pi 的實作 - 自動配置 IP 位址資訊的 DHCP Server
敗家學習之旅之樹莓派(Raspberry Pi) Realtek WIFI AP 架設成功心得分享

2016年4月21日星期四

新加坡四日遊 - 行程規劃、住宿、旅遊票卷

行程表
---------------------------------------------------------------------
10/8 (四)
01:05 - 05:50 桃園機場 → 樟宜機場

到新加坡首先要解決的是交通與上網的問題
- 辦SingTel hi! Tourist SIM $15，可到以下三個地方辦，便利商店是最方便，辦的時候記得指定SD, micro SD或nano SD卡。
  1. RHB Bank Currency Exchange Counters
  2. Changi Recommends Counters
  3. 便利商店
- 辦易通卡(EZ - Link Card)，建議旅人從樟宜機場第二航廈到達 SMRT 地鐵站後，就先在服務處購買一張 EZ-Link Card。

早餐
- Toast Box 吐司工坊 24 hours [Changi Airport T3]

- Haji Lane蘇丹回教堂 [EW12，Bugis 武吉士]
- 亞拉街(Arab St.) [EW12，Bugis 武吉士] 蘇丹回教堂後面

* 唐城坊 天宇旅行社，買優惠票 10:00~20:00 [NE4，China Town 牛車水 E出路]
  如果機場沒辦法辦Sintel，可以到唐城坊辦

- 牛車水郵局買郵票，在唐城坊附近 [NE4，China Town 牛車水 E出路]

午餐
- Maxwell Food Centre麥士威熟食中心 [EW15，Tanjong Pagar 、NE4，Chinatown 牛車水]
  天海南雞飯11:00~17:00
  松發肉骨茶
  金華魚片米粉
  老伴豆花
  真真粥品
  薏米水

- 馬里安興都廟 [NE4，China Town 牛車水]
- 亞坤咖椰吐司 總店 [NE4，China Town 牛車水]
- 史密斯街 寶塔街  [NE4，China Town 牛車水]
- 林志源肉乾 [NE4，China Town 牛車水]
- 味香園  [NE4，China Town 牛車水]
- 佛牙寺 [NE4，Chinatown 牛車水]

- 克拉碼頭 (末班22：30)  [NE5，克拉碼頭]
- 慕達發中心 [NE8，Farrer Park 花拉公園]

10/9 (五)
早餐
- Zam Zam 印度烤餅 [EW12，Bugis 武吉士]
- 哈芝巷喝咖啡 [EW12，Bugis 武吉士]
- 小印度拱廊 [NE7，Little India小印度、NE8，Farrer Park 花拉公園]
- 阿都卡夫回教堂 (09:00~13:00/ 14:30~18:30)  [NE7，Little India 小印度]

午餐
- 竹腳市場 囉惹 黃薑飯 印度煎餠 [NE7，Little India 小印度]
- 實龍崗路  [NE7，Little India 小印度]
- 烏節路 [NS22，Orcharad 烏節]

- 夜間動物園 19:30~24:00  [NS16，Ang Mo Kio 宏茂橋站] 走C出口轉138公車 30~40分
  http://www.nightsafari.com.sg/
  夜間動物表演: 晚上7.30、8.30、9.30以及10.30  *仅限星期五、星期六以及公共假期前夕
  婆羅洲土著表演: 傍晚6.45、晚上8.00、9.00以及10.00  *仅限星期五、星期六以及公共假期前夕。
  遊覽車探險體驗: 40分

10/10 (六)
早餐
- Luge斜坡渦車 Skyride空中吊車 [NE1，Harbour Front 港灣站 → 聖淘沙 Imbiah Station 英比奧捷運站]
- 海洋館 [NE1，Harbour Front 港灣站 → 聖淘沙 Imbiah Station 英比奧捷運站]

午餐
- 聖安德烈教堂 （EW13／NS25，City Hall 政府大廈）
- 萊佛士商場 [EW14／NS26，Raffles Place 萊佛士坊]
- 老巴剎沙嗲 [EW14／NS26，Raffles Place 萊佛士坊]

- Cavenagh Bridge加文納橋 [EW14／NS26，Raffles Place 萊佛士坊]
- Gardens by the bay 濱海灣花園 [CE1，Bayfront 海灣舫]
- Singapore Flyer新加坡摩天觀景輪 before 18:00 [CE1，Bayfront 海灣舫]
- 魚尾獅公園 燈光秀 8:00PM、9:30PM [EW14／NS26，Raffles Place 萊佛士坊]

10/11 (日)
- 結霜橋叻沙 09:00~18:00 [NE8，Farrer Park 花拉公園]
- Lady M 甜點 [EW14／NS26，Raffles Place 萊佛士坊]

10/12 (一)
00:45 - 05:20 樟宜機場 → 桃園機場


新加坡天氣
---------------------------------------------------------------------
匯率：1:24
氣候:：年均低溫24度，高溫31度 (短袖、短褲、雨傘)
簽證：免簽30天
桃園機場-->新加坡：約四個半小時
電器插頭：三孔式 (220-240V)


新加坡交通
---------------------------------------------------------------------
1. 易通卡 (EZ - Link Card)
http://home.ezlink.com.sg/get-your-ez-link-card/where-the-cards-are-sold

EZ - Link 卡儲值有效期為 5 年，可在各大地鐵站的 Transitlink Ticket Office 和 Passenger Service Centre 購買，
建議旅人從樟宜機場第二航廈到達 SMRT 地鐵站後，就先在服務處購買一張 EZ-Link Card，費用 SD 12 元，
其中包括可退的儲值金 SD 7 元及不可退的製卡工本費 SD 5 元。
PS. 搭乘地鐵最低餘額須大於 SD 3 元，每次加值最低須加值 SD 10 元。



SMRT 營業時間
週一至周六 首班車 05：16 末班車 23：30 ／週日及例假日 首班車 05：35 末班車 23：30。
從樟宜機場站（Changi Airport）開往丹那美拉站（Tanah Merah）
週一至周六 首班車 05：31 末班車 00：06 ／週日及假日 首班車 05：59 末班車 00：06
從丹那美拉站（Tanah Merah）開往樟宜機場站（Changi Airport）
週一至周六 首班車 05：20 末班車 23：50 ／週日及假日 首班車 05：47 末班車 23：50

【東行】2014年新加坡自由行--新加坡EZ-LINK儲值教學、交通方式介紹


新加坡上網
---------------------------------------------------------------------
1.  SingTel 
樟宜機場 or 唐城坊
新加坡旅遊超便宜預付卡手機3G/4G行動上網

Singtel hi!Tourist SIM: Packed with everything you need. 

hi! Tourist SIM (可以開熱點分享，也可以放到Wifi分享器供同行者使用，連線速度看別人寫的經驗大於3G)
15元：5天使用期，可享有500分鐘當地通話，100則SMS訊息，30分鐘國際電話，100GB流量，有Normal、Micro及Nano三種尺寸。可以再儲值1天5新幣延長使用天數，但是通話時間、簡訊、上網流量不會增加。




新加坡住宿
---------------------------------------------------------------------
1. Central 65 hotel [EW12，Bugis 武吉士] 1km，12分
  Address: 134 Jalan Besar Singapore 208852
  Front Desk Operation: 7:00am – 11:00pm
  Breakfast: 7:30am – 10:30am
  TEL: (+65) 6298 0015
  http://central65hostel.com/

2. Hotel ibis Singapore on Bencoolen [EW12，Bugis 武吉士] 500m，7分
  Address: 170 BENCOOLEN STREET 189657 - SINGAPORE
  TEL: (+65)65932888
  http://www.ibis.com/gb/hotel-6657-ibis-singapore-on-bencoolen/index.shtml


票價優惠 - 天宇旅行社
---------------------------------------------------------------------
唐城坊 天宇旅行社10:00~20:00 [NE4，China Town 牛車水 E出路]
[新加坡] 便宜票券哪裡買？？到天宇旅行社吧！！


新加坡地鐵站和聖淘沙地圖
---------------------------------------------------------------------

Raspberry Pi - 無線基地台路由模式 hostapd + udhcpd

1. 網路架構圖

          ---------------------------------------------
         |        wlan0          |         eth0        |
       LAN PC               Raspberry Pi             Modem
  IP: 192.168.1.100    WAN eth0:  192.168.0.100   IP: 192.168.0.1
  GW: 192.168.1.1      LAN wlan0: 192.168.1.1

3. Raspberry Pi啟動後，確認系統是否有正確抓到無線網卡

$ lsusb
Bus 001 Device 005: ID 3538:0901 Power Quotient International Co., Ltd
Bus 001 Device 004: ID 7392:7811 Edimax Technology Co., Ltd EW-7811Un 802.11n Wireless Adapter [Realtek RTL8188CUS]
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter
Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

4. 安裝hostapd套件，讓無線網卡模擬成Soft AP

$ sudo apt-get install hostapd

由於內建的hostapd不支援此張網卡，需要先移除hostpad程式，但保留相關的設定檔

$ sudo apt-get remove hostapd

透過wget命令，下載原廠無線網卡驅動程式到Raspberry Pi

$ wget http://12244.wpc.azureedge.net/8012244/drivers/rtdrivers/cn/wlan/0001-RTL8188C_8192C_USB_linux_v4.0.2_9000.20130911.zip

6. 安裝hostapd程式

$ unzip 0001-RTL8188C_8192C_USB_linux_v4.0.2_9000.20130911.zip

$ cd RTL8188C_8192C_USB_linux_v4.0.2_9000.20130911/wpa_supplicant_hostapd/

$ tar -zxvf wpa_supplicant_hostapd-0.8_rtw_r7475.20130812.tar.gz

$ cd wpa_supplicant_hostapd-0.8_rtw_r7475.20130812/hostapd

$ make clean && make && sudo make install

將hostapd相關檔案複製到/usr/bin

$ sudo cp /usr/local/bin/hostapd* /usr/sbin

7. 安裝wireless工具

$ cd ../../../wireless_tools

$ tar -zxvf wireless_tools.30.rtl.tar.gz

$ cd wireless_tools.30.rtl

$ make clean && make && sudo make install

8. 建立hostapd設定檔

driver: 無線網卡的驅動程式
ssid: 基地台名稱。
channel: 無線通訊的頻道，從1到11
wpa: 無線網路加密協定，1是WPA，2是WPA2
wpa_passphrase: 無線基地台的密碼。

$ sudo vi /etc/hostapd/hostapd.conf

interface=wlan0
driver=rtl871xdrv
bridge=br0
ssid=pi
channel=6
hw_mode=g
ieee80211n=1
wmm_enabled=1
wpa=2
wpa_passphrase=raspberry
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP
auth_algs=1
macaddr_acl=0

測試hosapd設定檔

$ sudo hostapd -dd /etc/hostapd/hostapd.conf

如沒有出現錯誤，按Ctrl+C停止hostapd，編輯hostapd服務設定檔

$ sudo vi /etc/default/hostapd

# Defaults for hostapd initscript
#
# See /usr/share/doc/hostapd/README.Debian for information about alternative
# methods of managing hostapd.
#
# Uncomment and set DAEMON_CONF to the absolute path of a hostapd configuration
# file and hostapd will be started during system boot. An example configuration
# file can be found at /usr/share/doc/hostapd/examples/hostapd.conf.gz
#
#DAEMON_CONF=""
DAEMON_CONF="/etc/hostapd/hostapd.conf"

# Additional daemon options to be appended to hostapd command:-
#       -d   show more debug messages (-dd for even more)
#       -K   include key data in debug messages
#       -t   include timestamps in some debug messages
#
# Note that -B (daemon mode) and -P (pidfile) options are automatically
# configured by the init.d script and must not be added to DAEMON_OPTS.
#
#DAEMON_OPTS=""

啟動hostapd服務

$ sudo service hostapd restart

開機時自動啟動hostapd服務

$ sudo update-rc.d hostapd defaults

9. 修改無線網路卡的設定值，設定一個指定的靜態 IP 位址

$ sudo vi /etc/network/interfaces

# interfaces(5) file used by ifup(8) and ifdown(8)

# Please note that this file is written to be used with dhcpcd
# For static IP, consult /etc/dhcpcd.conf and 'man dhcpcd.conf'

# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto lo
iface lo inet loopback

iface eth0 inet manual

allow-hotplug wlan0
iface wlan0 inet static
address 192.168.1.1
netmask 255.255.255.0

10. 路由模式需要在Raspberry Pi架設DHCP Server

$ sudo apt-get -y install udhcpd

將DHCPD_ENABLED="no"加上註解

$ sudo vi /etc/default/udhcpd 

# Comment the following line to enable
#DHCPD_ENABLED="no"

# Options to pass to busybox' udhcpd.
#
# -S    Log to syslog
# -f    run in foreground

DHCPD_OPTS="-S"

修改DHCP Server設定檔

$ sudo vi /etc/udhcpd.conf

# The start and end of the IP lease block

start           192.168.1.100   #default: 192.168.0.20
end             192.168.1.254   #default: 192.168.0.254

# The interface that udhcpd will use

interface       wlan0           #default: eth0


#Examles
opt     dns     8.8.8.8 192.168.1.1
option  subnet  255.255.255.0
opt     router  192.168.1.1
#opt    wins    192.168.10.10
#option dns     129.219.13.81   # appened to above DNS servers for a total of 3
#option domain  local
option  lease   864000          # 10 days of seconds

啟動DHCP Server服務

$ sudo service udhcpd restart

開機時自動啟動DHCP Server服務

$ sudo update-rc.d udhcpd defaults

11. 啟動IP Forwarding的功能，將net.ipv4.ip_forward=1拿掉註解

$ sudo vi /etc/sysctl.conf

# Uncomment the next line to enable packet forwarding for IPv4
net.ipv4.ip_forward=1

12. 啟用iptables NAT功能

$ sudo iptables -F
$ sudo iptables -F -t nat
$ sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
$ sudo iptables -A FORWARD -i eth0 -o wlan0 -m state --state RELATED,ESTABLISHED -j ACCEPT
$ sudo iptables -A FORWARD -i wlan0 -o eth0 -j ACCEPT

儲存目前iptables設定值

$ sudo bash -c 'iptables-save > /etc/network/iptables'
$ sudo iptables-restore < /etc/network/iptables

設定開機時，讓iptables的規則自動被載入

$ sudo vi /etc/rc.local

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

# Print the IP address
_IP=$(hostname -I) || true
if [ "$_IP" ]; then
  printf "My IP address is %s\n" "$_IP"
fi

sudo iptables-restore < /etc/network/iptables

exit 0

13. 重新啟動

$ sudo reboot

2016年4月20日星期三

Raspberry Pi - 播放MP3音效檔

1. 在Raspberry Pi播放MP3音效檔並不難，內建就有一個音效播放程式omxplayer，首先，先取得一個mp3音效檔

$ wget https://goo.gl/XJuOUW -O example.mp3 --no-check-certificate

2. 透過headphone jack介面播放測試音效

$ omxplayer -o local example.mp3
Audio codec mp3 channels 1 samplerate 11025 bitspersample 16
Subtitle count: 0, state: off, index: 1, delay: 0

如果想要透過HDMI介面播放測試音效，可以藉由參數來設定

$ omxplayer -o hdmi example.mp3
Audio codec mp3 channels 1 samplerate 11025 bitspersample 16
Subtitle count: 0, state: off, index: 1, delay: 0

3. 參考來源
https://www.raspberrypi.org/documentation/usage/audio/

Raspberry Pi - Hello audio 音效測試

1. Raspberry Pi提供一些Demo程式，為了測試音效的部份，需要進入hello_pi目錄

$ cd /opt/vc/src/hello_pi

2. 編譯Demo程式

./rebuild.sh

3. 進入Audo demo程式的目錄

$ cd hello_audio

$ ls
audio.c  audioplay.h  hello_audio.bin  Makefile  sinewave.c

4. 透過headphone jack介面播放測試音效

$ ./hello_audio.bin
Outputting audio to analogue

如果想要透過HDMI介面播放測試音效，可以藉由參數來設定

$ ./hello_audio.bin 1
Outputting audio to hdmi

5. 參考來源
https://www.raspberrypi.org/documentation/usage/demos/README.md
https://www.raspberrypi.org/documentation/usage/demos/hello-audio.md

2016年4月14日星期四

debugfs usage - SD card

1. To check SD speed mode by debugfs. It needs to enable the "Debug Fiflesystem" from menuconfig and then re-build kernel.

$ make linux-menuconfig

Kernel hacking  --->
  [*] Debug Filesystem

2. If the SPI mode is correct, the messages will be shown like below "5 (sd uhs DDR50)".

$ mount -t debugfs debug /mnt

$ cat /mnt/mmc0/ios
clock:          50000000 Hz
vdd:            15 (2.7 ~ 2.8 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      2 (4 bits)
timing spec:    5 (sd uhs DDR50)

Linux tcpdump 命令

1. tcpdump參數說明

Usage: tcpdump [-aAbdDefIKlLnNOpqRStuUvxX] [ -B size ] [ -c count ]
                [ -C file_size ] [ -E algo:secret ] [ -F file ] [ -G seconds ]
                [ -i interface ] [ -M secret ] [ -r file ]
                [ -s snaplen ] [ -T type ] [ -w file ] [ -W filecount ]
                [ -y datalinktype ] [ -z command ] [ -Z user ]
                [ expression ]

-n: 不把網路位址轉換成DNS名字
-i: 監控封包的網路介面
-w: 將監控封包儲存成檔案

2. 監控網路介面 br0

$ tcpdump -n -i br0 -w a.cap &

3. 監控網路介面 eth0

$ tcpdump -i eth0 -w a.cap

4. 監控網路介面 eth0，分割每個儲存的封包(size 1500bytes)

$ tcpdump -i eth0 -s 1500 -w a.cap

5. 顯示截取內容

$ tcpdump -r a.cap

Linux VLAN 命令

1. VLAN命令參數

Usage: vconfig COMMAND [OPTIONS]

Create and remove virtual ethernet devices

        add             [interface-name] [vlan_id]
        rem             [vlan-name]
        set_flag        [interface-name] [flag-num] [0 | 1]
        set_egress_map  [vlan-name] [skb_priority] [vlan_qos]
        set_ingress_map [vlan-name] [skb_priority] [vlan_qos]
        set_name_type   [name-type]

2. Create VLAN interface

$ vconfig add eth1 100
Added VLAN with VID == 100 to IF -:eth1:-

3. Remove VLAN interface

$ vconfig rem eth1.100

公司網路設定 - 內外網域共存

1. 有兩個網域，192.168.3.0為外網和10.194.0.0為內網，為了讓兩個共存需要修改routing table. 修改routing table，將192.168.0.0的網域提高priority。

$ route change 0.0.0.0 mask 0.0.0.0 192.168.3.1 if 11 metric 10
$ route change 0.0.0.0 mask 0.0.0.0 10.194.26.1 if 12 metric 30

2. 增加一條routing rule給DNS Server到172.18.0.0網域，走10.194.26.1的介面

$ route -p add 172.18.0.0 mask 255.255.0.0 10.194.26.1

3. 將DNS的mapping直接加入table，所以不需要DNS query

C:\WINDOWS\system32\drivers\etc\host

2016年4月13日星期三

iptables - port forwarding

PACKET IN
    |
PREROUTING--[routing]-->--FORWARD-->--POSTROUTING-->--OUT
 - nat (dst)   |           - filter      - nat (src)
               |                            |
               |                            |
              INPUT                       OUTPUT
              - filter                    - nat (dst)
               |                          - filter
               |                            |
               `----->-----[app]----->------'

      
The filter table has three built-in chains:
Forward chain: Filters packets destined for networks protected by the firewall.
Input chain: Filters packets destined for the firewall.
Output chain: Filters packets originating from the firewall.


The nat table has the following built-in chains:
Pre-routing chain: NATs packets when the destination address of the packet needs to be changed.
Post-routing chain: NATs packets when the source address of the packet needs to be changed.
Output chain: NATs packets originating from the firewall.

1. One to One port mapping

$ iptables -t nat -A PREROUTING -i eth1 -p udp --dport 1000 -j DNAT --to 192.168.1.10
$ iptables -t filter -A FORWARD -i eth1 -p udp -d 192.168.1.10 --dport 1000 -j ACCEPT

1000 -> 1000

$ iptables -t nat -A PREROUTING -i eth1 -p udp --dport 1000 -j DNAT --to 192.168.1.10:3000
$ iptables -t filter -A FORWARD -i eth1 -p udp -d 192.168.1.10 --dport 3000 -j ACCEPT

1000 -> 3000

2. Many to One port range mapping

$ iptables -t nat -A PREROUTING -i eth1 -p udp --dport 1000:2000 -j DNAT --to 192.168.1.10:3000
$ iptables -t filter -A FORWARD -i eth1 -p udp -d 192.168.1.10 --dport 3000 -j ACCEPT

1000 -> 3000
1001 -> 3000
...
1999 -> 3000
2000 -> 3000

3. One to One port range mapping

$ iptables -t nat -A PREROUTING -i eth1 -p udp --dport 1000:2000 -j DNAT --to 192.168.1.10
$ iptables -t filter -A FORWARD -i eth1 -p udp -d 192.168.1.10 --dport 1000:2000 -j ACCEPT

1000 -> 1000
1001 -> 1001
...
1999 -> 1999
2000 -> 2000

4. One to One port shift mapping

$ iptables -t nat -A PREROUTING -i eth1 -p udp --dport 1000:2000 -j DNAT --to 192.168.1.10:3000-4000
$ iptables -t filter -A FORWARD -i eth1 -p udp -d 192.168.1.10 --dport 3000:4000 -j ACCEPT

1000 -> 3000
1001 -> 3000
...
1999 -> 3000
2000 -> 3000

Linux kernel - printk level使用說明

1. Printk level說明

#define KERN_EMERG      "<0>"   /* system is unusable                   */
#define KERN_ALERT      "<1>"   /* action must be taken immediately     */
#define KERN_CRIT       "<2>"   /* critical conditions                  */
#define KERN_ERR        "<3>"   /* error conditions                     */
#define KERN_WARNING    "<4>"   /* warning conditions                   */
#define KERN_NOTICE     "<5>"   /* normal but significant condition     */
#define KERN_INFO       "<6>"   /* informational                        */
#define KERN_DEBUG      "<7>"   /* debug-level messages                 */

2. 修改printk level範例

$ echo 7 4 1 7 > /proc/sys/kernel/printk

3. 參數說明

3.1. console_loglevel
Messages with a higher priority than console_loglevel will be printed to the console.

3.2. default_message_level
Messages without an explicit priority will be printed with priority default_message_level.
              
3.3. Minimum_console_loglevel
minimum_console_loglevel is the minimum (highest) value to which console_loglevel can be set.

3.4. Default_console_loglevel
Default_console_loglevel is the default value for console_loglevel.

4. 參考來源
http://elinux.org/Debugging_by_printing

使用Linux script檢查coding style

1. checkpatch.pl Script位於kernel目錄下

./scripts/checkpatch.pl --help

Options:
  -q, --quiet                quiet
  --no-tree                  run without a kernel tree
  --no-signoff               do not check for 'Signed-off-by' line
  --patch                    treat FILE as patchfile (default)
  --emacs                    emacs compile window format
  --terse                    one line per report
  --showfile                 emit diffed file position, not input file position
  -f, --file                 treat FILE as regular source file
  --subjective, --strict     enable more subjective tests
  --types TYPE(,TYPE2...)    show only these comma separated message types
  --ignore TYPE(,TYPE2...)   ignore various comma separated message types
  --max-line-length=n        set the maximum line length, if exceeded, warn
  --min-conf-desc-length=n   set the min description length, if shorter, warn
  --show-types               show the message "types" in the output
  --root=PATH                PATH to the kernel tree root
  --no-summary               suppress the per-file summary
  --mailback                 only produce a report in case of warnings/errors
  --summary-file             include the filename in summary
  --debug KEY=[0|1]          turn on/off debugging of KEY, where KEY is one of
                             'values', 'possible', 'type', and 'attr' (default
                             is all off)
  --test-only=WORD           report only warnings/errors containing WORD
                             literally
  --fix                      EXPERIMENTAL - may create horrible results
                             If correctable single-line errors exist, create
                             ".EXPERIMENTAL-checkpatch-fixes"
                             with potential errors corrected to the preferred
                             checkpatch style
  --fix-inplace              EXPERIMENTAL - may create horrible results
                             Is the same as --fix, but overwrites the input
                             file.  It's your fault if there's no backup or git
  --ignore-perl-version      override checking of perl version.  expect
                             runtime errors.
  --codespell                Use the codespell dictionary for spelling/typos
                             (default:/usr/share/codespell/dictionary.txt)
  --codespellfile            Use this codespell dictionary
  --color                    Use colors when output is STDOUT (default: on)
  -h, --help, --version      display this help and exit

2. 帶入--file參數，檢查C source

$ scripts/checkpatch.pl --file *.c

3. 檢查patch file

$ scripts/checkpatch.pl *.patch

4. 一個範例 hello.c

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Allen");
MODULE_DESCRIPTION("A Simple Hello World module");

static int __init hello_init(void)
{
        printk(KERN_INFO "Enter module. Hello world!\n");
        return 0;
}

static void __exit hello_exit(void)
{
        printk(KERN_INFO "Exit module.\n");
}

module_init(hello_init);
module_exit(hello_exit);

$ ./scripts/checkpatch.pl --file hello.c 
WARNING: Prefer [subsystem eg: netdev]_info([subsystem]dev, ... then dev_info(dev, ... then pr_info(...  to printk(KERN_INFO ...
#11: FILE: ../../module/hello.c:11:
+ printk(KERN_INFO "Enter module. Hello world!\n");

WARNING: Prefer [subsystem eg: netdev]_info([subsystem]dev, ... then dev_info(dev, ... then pr_info(...  to printk(KERN_INFO ...
#17: FILE: ../../module/hello.c:17:
+ printk(KERN_INFO "Exit module.\n");

total: 0 errors, 2 warnings, 21 lines checked

../../module/hello.c has style problems, please review.

If any of these errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.

5. 參考來源
https://github.com/torvalds/linux/blob/master/scripts/checkpatch.pl

SHELL Script - 一個while loop的範例

1. Shell Script中，使用while loop語法

#!/bin/sh
i=1
while [ "$i" != "10" ]
do
    echo "loop" $i
    i=$(($i+1))
done

Result:
loop 1
loop 2
loop 3
loop 4
loop 5
loop 6
loop 7
loop 8
loop 9

2. 利用Shell Script產生多個VLAN interface

#!/bin/sh
i=1
while [ "$i" != "10" ]
do
    s=$(($i+1))
    vconfig add eth0 $i
    vconfig add eth1 $i
    ifconfig eth0.$i up
    ifconfig eth1.$i up
    brctl addbr br$i
    brctl addif br$i eth0.$i
    brctl addif br$i eth1.$i
    ifconfig br$i 192.168.$s.1 up
done

iperf 測試IPv6網路環境

1. Network topology

          ---------------------------------------------
         |        eth0          |         eth1        |
       LAN PC                 Router                WAN PC
  ip: 192.168.1.100    eth0: 192.168.1.1       ip: 10.1.1.100    IPv4
  gw: 192.168.1.1      eth1: 10.1.1.1          gw: 10.1.1.1 

  ip: 2001::100/64     eth0: 2001::10          ip: 2002::100     IPv6
  gw: 2002::/64        eth1: 2002::10          gw: 2001::/64

2. Set IPv6 address and default route

LAN PC:

$ ifconfig eth0 192.168.1.100
$ route add -net 10.1.0.0 gw 192.168.1.1
$ route add default gw 192.168.1.1

$ ip -6 addr add 2001::100/64 dev eth0
$ ip -6 route add 2002::/64 via 2001::10

DUT:

$ ifconfig eth0 192.168.1.1
$ ifconfig eth1 10.1.1.1
$ roue add default gw 10.1.1.100

$ ip -6 addr add 2001::10/64 dev eth0
$ ip -6 addr add 2002::10/64 dev eth1

WAN PC:

$ ifconfig eth0 10.1.1.100
$ route add -net 192.168.1.0 gw 10.1.1.1
$ route add default gw 10.1.1.1

$ ip -6 addr add 2002::100/64 dev eth1
$ ip -6 route add 2001::/64 via 2002::10

3. Enable IPv4 & IPv6 forwarding

$ echo 1 > /proc/sys/net/ipv4/ip_forward
$ echo 1 > /proc/sys/net/ipv6/conf/all/forwarding

4. IPv6 command

關閉IPv6: echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6
開啟forward功能: echo 0 > /proc/sys/net/ipv6/disable_forward

新增網卡IP: ip -6 addr add 2001::1234 dev eth0
新增網卡IP(2): ifconfig eth0 inet6 add 2001::1234/64
清除網卡IP: ip -6 addr flush dev eth0

新增路由: ip -6 route add 2345::/64 via fe80::1234 dev eth0
刪除路由: ip -6 route del 2345::/64 via fe80::1234 dev eth0
新增預設路由: ip -6 route add default via fe80::1234 dev eth0 
清除所有路由: ip -6 route flush dev eth0

iperf 測試IPv4網路環境

1. Network topology

          ---------------------------------------------
         |        eth0          |         eth1        |
       LAN PC                 Router                WAN PC
  ip: 192.168.1.100    eth0: 192.168.1.1       ip: 10.1.1.100
  gw: 192.168.1.1      eth1: 10.1.1.1          gw: 10.1.1.1
                       gw  : 10.1.1.100

2. Set IPv4 address and default route

LAN PC:

$ ifconfig eth0 192.168.1.100
$ route add -net 10.1.0.0 gw 192.168.1.1
$ route add default gw 192.168.1.1

DUT:

$ ifconfig eth0 192.168.1.1
$ ifconfig eth1 10.1.1.1
$ roue add default gw 10.1.1.100

WAN PC:

$ ifconfig eth0 10.1.1.100
$ route add -net 192.168.1.0 gw 10.1.1.1
$ route add default gw 10.1.1.1

3. Enable IPv4 forwarding

$ echo 1 > /proc/sys/net/ipv4/ip_forward

4. IPv4 command

啟動網卡: ifconfig eth0 up
啟動網卡(2): ifup eth0
關閉網卡: ifconfig eth0 down
關閉網卡(2): ifdown eth0

設定MTU: ifconfig eth0 1500
開啟forward功能: echo 1 > /proc/sys/net/ipv4/ip_forward

設定網卡IP: ifconfig eth0 192.168.0.1/24
增加網卡IP: ip -4 addr add 192.168.0.2/24 dev eth0
刪除網卡IP: ip -4 addr del 192.168.0.2/24 dev eth0
清除網卡IP: ip -4 addr flush dev eth0

透過DHCP取得IP: dhclient eth0
釋放DHCP IP: dhclient -r eth0

新增路由: route add -net 192.168.0.0/24 gw 192.168.0.1 dev eth0
刪除路由: route del -net 192.168.0.0/24 gw 192.168.0.1 dev eth0
新增預設路由: route add default gw 192.168.0.1 dev eth0

Raspberry Pi - 建立一個網路橋接器 Bridge

1. 網路架構圖

  Bridge
        br0             virtual adapter
         |
   --------------       bridge
   |            |
  eth0         eth1     physical adapters

2. 將網路介面啟動

$ ifconfig eth0 0.0.0.0 up
$ ifconfig eth1 0.0.0.0 up

3. 新增一個bridge介面，並把實體介面加入

$ brctl addbr br0
$ brctl addif br0 eth0
$ brctl addif br0 eth1

4. 設定bridge介面的IP address

$ ifconfig br0 192.168.1.1

線上程式編譯器 tutorialspoint

1. 進入tutorialspoint網站，點選C Compiler
http://www.tutorialspoint.com/codingground.htm

2. 點選Compiler編譯原始碼

3. 執行程式

2016年4月12日星期二

WPS PIN Code的規則

1. WPS PIN Code checksum運算
For 8-digit numeric PINs, the last digit in the PIN is used as a checksum of the other digits. 

Ex:
The 7-digit numeric PINs is "1234567".
The 8th digit should be "0".

 ( 1*3 + 2*1 + 3*3 + 4*1 + 5*3 + 6*1 + 7*3 ) = 60
 60 % 10 = 0
 10 - 0 = 10
 10 % 10 = 0
 Get the 8th digit is "0".
 So the 8-digit numberic PINs is "12345670".
 
If the 7-digit numberic PINs is "5967201", 
the 8th digit should be "2".
 ( 5*3 + 9*1 + 6*3 + 7*1 + 2*3 + 0*1 + 1*3) = 58
 58 % 10 = 8
 10 - 8 = 2
 2 % 10 = 2
 Get the 8th digit is "2".
 So the 8-digit numberic PINs is "59672012".

The corresponding algorithm to compute the checksum digit given the other seven random PIN digits is:

/**
 * wps_pin_checksum - Compute PIN checksum
 * @pin: Seven digit PIN (i.e., eight digit PIN without the checksum digit)
 * Returns: Checksum digit
 */
unsigned int wps_pin_checksum(unsigned int pin)
{
 unsigned int accum = 0;
 while (pin) {
  accum += 3 * (pin % 10);
  pin /= 10;
  accum += pin % 10;
  pin /= 10;
 }

 return (10 - accum % 10) % 10;
}

2. 驗證WPS PIN Code是否合法 The algorithm to validate the checksum is given in C code below.

/**
 * wps_pin_valid - Check whether a PIN has a valid checksum
 * @pin: Eight digit PIN (i.e., including the checksum digit)
 * Returns: 1 if checksum digit is valid, or 0 if not
 */
unsigned int wps_pin_valid(unsigned int pin)
{
 return wps_pin_checksum(pin / 10) == (pin % 10);
}

3. 參考來源
http://ftp.netbsd.org/pub/NetBSD/NetBSD-release-6/src/external/bsd/wpa/dist/src/wps/wps_common.c

無線網路 802.11n 20MHz 和 40MHz 的 Data Rate

2016年4月10日星期日

現在生活這麼難過，除了能省則省外，也要懂得想些方法賺現金，其中一個方法就是刷信用卡消費，利用紅利點數換取eTag回饋金，以下以國泰世華信用卡為範例。

1. 紅利點數說明
刷卡享2倍紅利或現金回饋
卡友每刷卡 20 元就可累積紅利點數 2 點或 0.5% 現金回饋 ( 二擇一 ) ，點數期限三年有效。

2. 紅利點數兑換項目
刷卡NT$20累積紅利1點，每1,000點紅利可兌換60元eTag回饋金。

3. 回饋利率說明
國泰世華網頁說明，1000點可以換取60元eTag回饋金
信用卡的紅利點數說明，20元可以累積紅利點數2點，1000點則需要消費10000元。利率計算 60元 / 10000元 = 0.006，相當於0.6%。

Google AdSense 申請成功

2016/04/02:

2016/04/03:

2016年4月8日星期五

Git GUI 工具整理

1. Linux base git tools
Git-cola
SmartGit
Git Gui

2. Linux base git viewer
Gitg
Giggle
qGit
Gitk

3. Windows base tools
TortoiseGit
Git Hub Desktop

Linux Git 圖形界面 - Qgit

1. 在putty，enable X11 fordwarding

2. 透過putty登入伺服器主機

3. 安裝qgit

$ sudo apt-get install qgit

4. 一個lmbench的範例，從github下載lmbench，在lmbench的git repository資料夾裡，啟動qgit

$ qgit

5. 參考來源
http://digilander.libero.it/mcostalba/
https://www.maketecheasier.com/6-useful-graphical-git-client-for-linux/

Linux Git 圖形界面 - Giggle

1. 在putty，enable X11 fordwarding

2. 透過putty登入伺服器主機

3. 安裝giggle

$ sudo apt-get install giggle

4. 一個lmbench的範例，從github下載lmbench，在lmbench的git repository資料夾裡，啟動giggle

$ giggle

5. 參考來源
https://wiki.gnome.org/Apps/giggle/
https://www.maketecheasier.com/6-useful-graphical-git-client-for-linux/

Linux Git 圖形界面 - Gitg

1. 在putty，enable X11 fordwarding

2. 透過putty登入伺服器主機

3. 安裝gitg

$ sudo apt-get install gitg

4. 一個lmbench的範例，從github下載lmbench，在lmbench的git repository資料夾裡，啟動gitg

$ gitg

5. 參考來源
https://wiki.gnome.org/Apps/Gitg/
https://www.maketecheasier.com/6-useful-graphical-git-client-for-linux/

2016年4月7日星期四

Linux Git 圖形界面 - Gitk

1. 在putty，enable X11 fordwarding

2. 透過putty登入伺服器主機

3. 一個lmbench的範例，從github下載lmbench，在lmbench的git repository資料夾裡，啟動gitk

$ gitk --all

4. 參考來源
https://git-scm.com/docs/gitk

Raspberry Pi - 建立一個網路路由器 Router

1. 網路架構圖

          ---------------------------------------------
         |        eth0          |         eth1        |
       LAN PC                 Router                WAN PC
  ip: 192.168.1.100    eth0: 192.168.1.1       ip: 10.1.1.100
  gw: 192.168.1.1      eth1: 10.1.1.1          gw: 10.1.1.1

2. 設定網路介面的IP address，eth0為LAN interface，eth1為WAN interface

$ ifconfig eth0 192.168.1.1
$ ifconfig eth1 up

3. 在WAN interface eth1啟動dhcp client去跟外面的dhcp server要IP

$ udhcpc -i eth1

4. 開啟IPv4 forwrding功能

$ sudo bash -c 'echo 1 > /proc/sys/net/ipv4/ip_forward'

5. 開啟iptables NAT功能

$ iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE

6. 設定default gateway

$ route add default gw 10.1.1.1

7. 在LAN interface eth0啟動dhcp server，設定dhcp server的configuration file
example 1:

echo "start     192.168.1.20" > /etc/udhcpd.conf
echo "end       192.168.1.254" >> /etc/udhcpd.conf
echo "interface br0" >> /etc/udhcpd.conf

echo "opt       dns     192.168.1.1 192.168.1.1" >> /etc/udhcpd.conf
echo "option    subnet  255.255.255.0" >> /etc/udhcpd.conf
echo "opt       router  192.168.1.1" >> /etc/udhcpd.conf
echo "opt       wins    192.168.1.1" >> /etc/udhcpd.conf
echo "option    dns     192.168.1.1" >> /etc/udhcpd.conf
echo "option    domain  local" >> /etc/udhcpd.conf
echo "option    lease   864000" >> /etc/udhcpd.conf

echo "static_lease 00:24:BE:7E:AE:C1 192.168.1.100" >> /etc/udhcpd.conf

example 2:

echo "start     192.168.1.20" > /etc/udhcpd.conf
echo "end       192.168.1.254" >> /etc/udhcpd.conf
echo "interface eth0" >> /etc/udhcpd.conf

echo "opt       dns     192.168.1.1 192.168.1.1" >> /etc/udhcpd.conf
echo "option    subnet  255.255.255.0" >> /etc/udhcpd.conf
echo "opt       router  192.168.1.1" >> /etc/udhcpd.conf
echo "opt       wins    192.168.1.1" >> /etc/udhcpd.conf
echo "option    dns     192.168.1.1" >> /etc/udhcpd.conf
echo "option    domain  local" >> /etc/udhcpd.conf
echo "option    lease   864000" >> /etc/udhcpd.conf

echo "static_lease 00:24:BE:7E:AE:C1 192.168.1.100" >> /etc/udhcpd.conf

8. 在LAN interface eth0啟動dhcp server，以供LAN side的主機取得IP

$ mkdir /var/lib/misc/
$ touch /var/lib/misc/udhcpd.leases
$ udhcpd

9. 啟動DNS MASQUERATE

$ dnsmasq

putty 避免SSH連線中斷 keepalives

Connection->Seconds between keepalives

Kernel trace

include/linux/etherdevice.h
include/linux/netdevice.h

// ethernet header
include/linux/if_ether.h
// pppoe header    
include/linux/if_pppox.h
include/linux/if_vlan.h
// IPv4 header
include/linux/ip.h
// IPv6 header
include/linux/ipv6.h
// TCP header
include/linux/tcp.h
// UDP header
include/linux/udp.h

// SK buffer
include/linux/skbuff.h

include/linux/netfilter_bridge/ebt_pppoe.h

include/net/sock.h



net/core/dev.c
net/ethernet/eth.c
net/core/skbuff.c

// bridge
net/bridge/br_forward.c

net/bridge/netfilter/ebt_pppoed.c
net/bridge/netfilter/ebt_pppoes.c

// VLAN packet
net/8021q/vlan_dev.c

// Arp packet
net/ipv4/arp.c

// ICMP packet
net/ipv4/icmp.c

SHELL Script加入文字樣式, 文字顏色, 背景顏色

以shell 的顯示為例，顯示的格式如下：

\33[ 文字樣式 ; 文字顏色 ; 背景顏色 m
文字內容………………
\33[0m

1. 文字樣式，有列下幾種色碼可以使用：
0 一般亮度
1 高度度
4 加底線
5 灰底

2. 文字顏色，則都是3開頭，有下列色碼：
30 黑色
31 紅色
32 綠色
33 黃色
34 藍色
35 紫色
36 青綠
37 白色

3. 背景顏色，色碼都是4開頭：
40 黑色
41 紅色
42 綠色
43 黃色
44 藍色
45 紫色
46 青綠
47 白色

4.範例
如果我要在畫面上顯示高亮度的綠色(32)及黑色背景，可以如下：

echo -e "\e[1;32;40m 我的文字 \e[0m"

也可以分開來寫比較清楚

echo -e "\e[1;32;40m "  
echo -e "我的文字"  
echo -e "\e[0m"

一個應用程式Makefile範例

cc = gcc
strip = strip
CFLAGS = -Wall -Wextra -static
APPLET = myapp

all: $(TARGET)

$(TARGET): main.o
        @echo "\033[32mBuilding $(TARGET) ...\033[0m"
        @$(CC) $(CFLAGS) -o $@ $^
        @(STRIP) $(TARGET)
        @./$(TARGET)

install:
        @echo "\033[32mInstalling $(TARGET) ...\033[0m"

clean:
        @echo "\033[32mCleaning $(TARGET) ...\033[0m"
        @rm -f $(TARGET) *.o

.PHONY: all install clean

Kernel module和Makefile範例

1. 準備hello.c和Makefile

$ vi hello.c

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Allen");
MODULE_DESCRIPTION("A Simple Hello World module");

static int __init hello_init(void)
{
    printk(KERN_INFO "Enter module. Hello world!\n");
    return 0;
}

static void __exit hello_exit(void)
{
    printk(KERN_INFO "Exit module.\n");
}

module_init(hello_init);
module_exit(hello_exit);

$ vi Makefile

obj-m += hello.o

all:
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

clean:
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

2. 編譯Hello world的kernel module

$ make
make -C /lib/modules/3.11.0-15-generic/build M=/home/allen/Work/module modules
make[1]: Entering directory `/usr/src/linux-headers-3.11.0-15-generic'
  CC [M]  /home/allen/Work/module/hello.o
  Building modules, stage 2.
  MODPOST 1 modules
  CC      /home/allen/Work/module/hello.mod.o
  LD [M]  /home/allen/Work/module/hello.ko
make[1]: Leaving directory `/usr/src/linux-headers-3.11.0-15-generic'


$ ls
hello.c   hello.mod.c  hello.o   modules.order
hello.ko  hello.mod.o  Makefile  Module.symvers

3. 掛載Hello world的kernel module

$ sudo insmod hello.ko

$ dmesg | tail -1
[18253.619885] Enter module. Hello world!

4. 卸載Hello world的kernel module

$ sudo rmmod hello

$ dmesg | tail -1
[18291.787154] Exit module.

5. 列出已掛載kernel module

$ lsmod | grep hello
hello                  12425  0

6. 顯示module的資訊

$ modinfo hello.ko
filename:       hello.ko
description:    A Simple Hello World module
author:         Allen
license:        GPL
srcversion:     4022E1AB22D5C59AACC7122
depends:
vermagic:       3.11.0-15-generic SMP mod_unload modversions

7. 參考來源
How to Write Your Own Linux Kernel Module with a Simple Example

2016年4月6日星期三

英文標點符號的使用

句點（Full Stop / Period， “.”） 

問號（Question Mark， “？”） 

感嘆號（Exclamation Mark， “!”） 

逗點（Comma， “,”） 

冒號（Colon， “:”） 

分號（Semicolon， “;”） 

連字元（Hyphen， “-”） 

連接號（En Dash， “–”） 

破折號（Em Dash， “—”） 

括弧（Parentheses， 小括弧“( )”； 中括弧“[]”； 大括弧“{}”） 

引號（Quotation Marks， 雙引號“"”； 單引號“‘”） 

縮寫及所有格符號（Apostrophe， “‘”）

參考來源
http://tw.blog.voicetube.com/2014/11/21/%E3%80%90%E5%AF%A6%E7%94%A8%E3%80%91%E4%BD%A0%E7%9F%A5%E9%81%93%E8%8B%B1%E6%96%87%E7%9A%84%E6%A8%99%E9%BB%9E%E7%AC%A6%E8%99%9F%E6%80%8E%E9%BA%BC%E4%BD%BF%E7%94%A8%E5%97%8E%EF%BC%9F%E6%96%87%E7%AB%A0

https://www.google.com.tw/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwiwiemKqPnLAhXKoZQKHaGXD1oQFgghMAE&url=http%3A%2F%2Flms.ctl.cyut.edu.tw%2Fblog%2Flib%2Fread_attach.php%3Fid%3D1859&usg=AFQjCNF9OVsPHsfW8urKmIYZnwNs8eY6Wg&sig2=EHhOl5bTtb7D4ODnWb6FbA

WebEx錄像軟體用法

1. 下載WebEx
http://www.webex.com.hk/support/play-webex-recording.html

2. 安裝WebEx

3. 開啟WebEx，開始錄像

4. 參考來源
http://www.webex.com.hk/support/play-webex-recording.html

2016年4月5日星期二

iptables port forwarding範例

1. 網路架構圖

# Port forward
        192.168.1.1    20.1.1.10
LAN PC ------------ DUT ------------- WAN PC
192.168.1.100:5555                   20.1.1.100

2. 各主機所下達的命令 LAN PC:

$ iperf -s -u -p 5555

WAN PC:

$ iperf -c 20.1.1.10 -t 600 -i 5 -u -l 1400 -p 4444

DUT:

$ iptables -t nat -A PREROUTING -d 20.1.1.10 -p udp -i ppp0 --dport 4444 -j DNAT --to-destination 192.168.1.100:5555

iperf使用範例

iperf是用來產生網路流量，可以用來測試網路設備，

# iperf -h
Usage: iperf [-s|-c host] [options]
       iperf [-h|--help] [-v|--version]

Client/Server:
  -f, --format    [kmKM]   format to report: Kbits, Mbits, KBytes, MBytes
  -i, --interval  #        seconds between periodic bandwidth reports
  -l, --len       #[KM]    length of buffer to read or write (default 8 KB)
  -m, --print_mss          print TCP maximum segment size (MTU - TCP/IP header)
  -o, --output     output the report or error message to this specified file
  -p, --port      #        server port to listen on/connect to
  -u, --udp                use UDP rather than TCP
  -w, --window    #[KM]    TCP window size (socket buffer size)
  -B, --bind         bind to , an interface or multicast address
  -C, --compatibility      for use with older versions does not sent extra msgs
  -M, --mss       #        set TCP maximum segment size (MTU - 40 bytes)
  -N, --nodelay            set TCP no delay, disabling Nagle's Algorithm
  -V, --IPv6Version        Set the domain to IPv6

Server specific:
  -s, --server             run in server mode
  -U, --single_udp         run in single threaded UDP mode
  -D, --daemon             run the server as a daemon

Client specific:
  -b, --bandwidth #[KM]    for UDP, bandwidth to send at in bits/sec
                           (default 1 Mbit/sec, implies -u)
  -c, --client       run in client mode, connecting to 
  -d, --dualtest           Do a bidirectional test simultaneously
  -n, --num       #[KM]    number of bytes to transmit (instead of -t)
  -r, --tradeoff           Do a bidirectional test individually
  -t, --time      #        time in seconds to transmit for (default 10 secs)
  -F, --fileinput    input the data to be transmitted from a file
  -I, --stdin              input the data to be transmitted from stdin
  -L, --listenport #       port to receive bidirectional tests back on
  -P, --parallel  #        number of parallel client threads to run
  -T, --ttl       #        time-to-live, for multicast (default 1)
  -Z, --linux-congestion   set TCP congestion control algorithm (Linux only)

Miscellaneous:
  -x, --reportexclude [CDMSV]   exclude C(connection) D(data) M(multicast) S(settings) V(server) reports
  -y, --reportstyle C      report as a Comma-Separated Values
  -h, --help               print this message and quit
  -v, --version            print version information and quit

產生IPv6的封包: -V, --IPv6Version Set the domain to IPv6

Server:
$ iperf -V -s -i 5

Client
$ iperf -V -c 2001:2222::2 -t 172800 -i 5 -u

產生TCP的封包: 預設為TCP封包

Server
$ iperf -s -i 5

Client
$ iperf -c 192.168.1.100 -t 172800 -i 5

產生UDP的封包: -u, --udp use UDP rather than TCP

Server
$ iperf -s -i 5 -u

Client
$ iperf -c 192.168.1.100 -t 172800 -i 5 -u

產生指定Port number的封包: -p, --port # server port to listen on/connect to

Server
$ iperf -s -i 5 -p 100 -u

Client
$ iperf -c 192.168.1.100 -t 172800 -i 5 -p 100 -u

產生指定Bandwidth的流量: -b, --bandwidth #[KM] for UDP, bandwidth to send at in bits/sec

Server
$ iperf -s -i 5 -u

Client
$ iperf -c 192.168.1.100 -t 172800 -i 5 -b 10M -u

產生DSCP的封包: 7 (28/ 4)的封包

Server
$ iperf -s -i 5 -u

Client
$ iperf -c 192.168.1.100 -t 172800 -i 5 -S 28 -u

產生指定Payload size的封包: 1200 bytes的封包

Server
$ iperf -s -i 5 -u

Client
$ iperf -c 20.1.1.100 -t 20 -i 5 -u -l 1200

參考來源
https://iperf.fr/
https://iperf.fr/iperf-doc.php

Git 命令整理

git add 新增檔案

git add . 新增目錄下所有檔案

git commit 提交檔案

git commit -m 'message' 直接提交，不進入編輯器
git commit 提交檔案，進入編輯器
git commit --amend 編輯已提交的註釋

git reset 回復檔案

git reset 放棄add，保留修改
git reset --hard 放棄所有修改，回到上個提交的狀態
git reset --hard HEAD 回到最新提交的版本
git reset --hard HEAD^ 回到前一個提交的版本

git branch 分支

git branch 列出所有branch
git branch -a 列出所有本地和遠端的branch
git branch <new-branch> 依目前branch，建立新的branch

git checkout 切換

git checkout <branch> 切換branch
git checkout master 切換到master
git checkout <new-branch> master 從master建立新的branch，並切換到新的branch
git checkout -b <new-branch> 依目前branch建立新的branch，並切換到新的branch
git checkout <file> 重新checkout此檔案

git log

git log 列出所有log

git pull

git pull 將遠端的檔案更新到本地

git push

git push 將本地檔案更新到遠端

參考來源
https://www.atlassian.com/git/tutorials/setting-up-a-repository
https://git-scm.com/doc
https://backlogtool.com/git-guide/tw/

GCC使用方法

1. Compiler a source file

$ gcc -o hello hello.c

2. Compiler many source files

$ gcc -o hello hello.c func.c

3. Compiler source file with debug flag

$ gcc -g -o hello hello.c

4. 編譯動態連結

$ arm-linux-gcc -Wall -c -o hrt_timer.o hrt_timer.c
$ arm-linux-gcc -Wall -o hrt_timer hrt_timer.o -lrt

5. 編譯靜態連結

$ arm-linux-gcc -Wall -c -o hrt_timer.o hrt_timer.c
$ arm-linux-gcc -Wall -static -o hrt_timer hrt_timer.o -lrt

6. preprofessor

$ gcc -E

Linux find 命令

1. find，配合萬用元字找尋檔案

$ find -name *.c -o -name *.h

2.1. find，配合萬用元字找尋檔案
2.2. xargs，將上一個程式輸出的結果轉成下一個程式的參數輸入
2.3. grep，找尋包含DEBUG的字串

$ find . -name "*.h" | xargs grep -r DEBUG

3.1. find，配合萬用元字找尋檔案
3.2. -exec，是表示找到檔案後要執行的指令
3.3. rm -rf，強制刪除檔案
3.4. {}，代表指令接檔案名稱的地方，find會將找到檔案的檔名與路徑帶入到{}
3.5. \;，代表指令結束，不可以省略

$ find . -name .svn -exec rm -rf {} \;

4.1. find，配合萬用元字找尋檔案
4.2. xargs，將上一個程式輸出的結果轉成下一個程式的參數輸入
4.3. rm -rf，強制刪除檔案

$ find . -name .svn | xargs rm -rf

Linux diff 和 patch 命令

1. Create a patch

$ diff -urN a/trunk b/trunk > c.patch

-a --text Treat all files as text.
-u -U NUM --unified[=NUM] Output NUM (default 3) lines of unified context.
-r --recursive Recursively compare any subdirectories found.
-N --new-file Treat absent files as empty.

2. Apply patch

$ patch -p1 < c.patch

-p0，Do not get rid of any level
-p1，Get rid of first level
-p2，Get rid of secondary level
-p NUM --strip=NUM Strip NUM leading components from file names.
-R --reverse Assume patches were created with old and new files swapped.

3. Restore the patch file

$ patch -R -p1 < c.patch

ethtool使用方法

1. Printf the offload setting

$ ethtool -k eth0

Offload parameters for eth0: 
rx-checksumming: on 
tx-checksumming: on 
scatter-gather: on 
tcp-segmentation-offload: on 
udp-fragmentation-offload: off 
generic-segmentation-offload: on 
generic-receive-offload: on 
large-receive-offload: off

這些offload特性都是為了提升網路收/發效能。TSO、UFO和GSO是對應網路發送，在接收方向上對應的是LRO、GRO。

2. TSO (TCP Segmentation Offload)

$ ethtool -K eth0 tso on
$ ethtool -K eth0 tso off

TSO是一種利用網卡對TCP封包分裝，減輕CPU負荷的一種技術，有時也被叫做LSO (Large Segment Offload)，TSO是針對TCP的，UFO是針對UDP的。如果硬體支援TSO功能，同時也需要硬體支援的TCP checksum計算和分散/聚集(Scatter Gather)功能。

3. UFO (UDP Fragmentation Offload)

$ ethtool -K eth0 ufo on
$ ethtool -K eth0 ufo off

4. GSO (Generic Segmentation Offload)

$ ethtool -K eth0 gso on
$ ethtool -K eth0 gso off

GSO比TSO更通用，基本思想就是盡可能的將大封包分裝直至發送到網卡驅動之前，此時會檢查網卡是否支援分裝功能(如TSO、UFO)，如果支援直接發送到網卡，如果不支援就進行分片後再發往網卡。這樣大封包只需走一次protocol stack，而不是被分割成幾個小封包分別走，這就提高了效率。

5. LRO (Large Receive Offload)

$ ethtool -K eth0 lro on
$ ethtool -K eth0 lro off

LRO通過將接收到的多個TCP封包組合成一個大的封包，然後傳遞給protocol stack處理，以減少上層protocol stack的處理，提高系統接收TCP封包的能力。

6. GRO (Generic Receive Offload)

$ ethtool -K eth0 gro on
$ ethtool -K eth0 gro off

GRO基本思想跟LRO類似，克服了LRO的一些缺點，更通用。後續的驅動都使用GRO的接口，而不是LRO。

7. RSS (Receive Side Scaling)
RSS是一項網卡的新特性，俗稱多隊列。具備多個RSS隊列的網卡，可以將不同的網絡流分成不同的隊列，再分別將這些隊列分配到多個CPU核心上進行處理，從而將負荷分散，充分利用多核處理器的能力。

網路封包長度整理

- Ethernet Packet
Ethernet Header = ( 6 SRCMAC + 6 DSTMAC + 2 TYPE ) = 14 B
Ethernet Packet MinSize = ( 6 SRCMAC + 6 DSTMAC + 2 TYPE + 4 CRC + 46 PAYLOAD ) = 64 B
Ethernet Packet MaxSize = ( 6 SRCMAC + 6 DSTMAC + 2 TYPE + 4 CRC + 1500 PAYLOAD ) = 1518 B

- TCP Packet
Ethernet Header = 14 B
IP Header = 20 B
TCP Header MinSize = 20
TCP Header MaxSize = (20 TCP_HEADER + 40 OPTION) = 60 B

TCP Packet MinSize = ( 14 ETHERNET_HEADER + 20 IP_HEADER + 20 TCP_HEADER ) = 54 B
TCP Packet MaxSize = ( 14 ETHERNET_HEADER + 20 IP_HEADER + 60 TCP_HEADERP ) = 94 B

- UDP Packet
Ethernet Header = 14 B
IP Header = 20 B
UDP Header = 8 B

UDP Packet = ( 14 ETHERNET_HEADER + 20 IP_HEADER + 8 UDP_HEADER ) = 42 B



- PPPoE packet
PPP Header = 2 B
PPPoE Session = 6 B

TCP over PPPoE MinSize = ( 14 ETHERNET_HEADER + 6 PPPoE_SESSION + 2 PPP_HEADER + 20 IP_HEADER + 20 TCP_HEADER ) = 62 B 
TCP over PPPoE MaxSize = ( 14 ETHERNET_HEADER + 6 PPPoE_SESSION + 2 PPP_HEADER + 20 IP_HEADER + 60 TCP_HEADER ) = 102 B
UDP over PPPoE = ( 14 ETHERNET_HEADER + 6 PPPoE_SESSION + 2 PPP_HEADER + 20 IP_HEADER + 8 UDP_HEADER ) = 50 B
Ethernet IP MTU = 1518 - 18 ( 6 SRCMAC+ 6 DSTMAC+ 2 TYPE+ 4 CRC) = 1500 B
Ethernet IP TCP MSS = 1500 - 40 ( 20 IP_HEADER + 20 TCP_HEADER) = 1460 B
Ethernet IP UDP MTU/MRU = 1500 - 28 ( 20 IP_HEADER + 8 UDP_HEADER ) = 1472 B

PPPoE MTU/MRU = 1500 - 8 ( 6 PPPoE_SESSION + 2 PPP_HEADER ) = 1492 B
TCP over PPPoE MSS = 1492 ( PPPoE MTU/MRU ) - 40 ( 20 IP_HEADER + 20 TCP_HEADER) = 1452
UDP over PPPoE MTU/MRU = 1492 ( PPPoE MTU/MRU ) - 28 ( 20 IP_HEADER + 8 UDP_HEADER ) = 1464

PPTP MTU/MRU = 1500 - 56 ( 20 IP_HEADER + 20 TCP_HEADER + 12 GRE_HEADER + 4 PPP_HEADER ) = 1444 B
TCP over PPTP MSS = 1444 ( PPTP MTU/MRU ) - 40 ( 20 IP_HEADER + 20 TCP_HEADER) = 1404

L2TP MTU/MRU = 1500 - 40 ( 20 IP_HEADER +8 UDP_HEADER + 8 L2TP_HEADER + 4 PPP_HEADER ) = 1460 B
TCP over L2TP MSS = 1460 ( L2TP MTU/MRU ) - 40 ( 20 IP_HEADER + 20 TCP_HEADER) = 1420 B

PPTP over PPPoE MTU/MRU = 1492 ( PPPoE MTU/MRU ) - 56 ( 20 IP_HEADER + 20 TCP_HEADER + 12 GRE_HEADER + 4 PPP_HEADER ) = 1436 B

PPTP over PPTP MTU/MRU = 1444 ( PPTP MTU/MRU ) - 56 ( 20 IP_HEADER + 20 TCP_HEADER + 12 GRE_HEADER + 4 PPP_HEADER ) = 1388 B

PPTP over L2TP MTU/MRU = 1460 ( L2TP MTU/MRU ) - 56 ( 20 IP_HEADER + 20 TCP_HEADER + 12 GRE_HEADER + 4 PPP_HEADER ) = 1404 B

L2TP over PPPoE MTU/MRU = 1492 ( PPPoE MTU/MRU ) - 40 ( 20 IP_HEADER +8 UDP_HEADER + 8 L2TP_HEADER + 4 PPP_HEADER ) = 1452 B

L2TP over PPTP MTU/MRU = 1444 ( PPTP MTU/MRU ) - 40 ( 20 IP_HEADER +8 UDP_HEADER + 8 L2TP_HEADER + 4 PPP_HEADER ) = 1404 B

L2TP over L2TP MTU/MRU = 1460 ( L2TP MTU/MRU ) - 40 ( 20 IP_HEADER +8 UDP_HEADER + 8 L2TP_HEADER + 4 PPP_HEADER ) = 1420 B