Microsoft Network Load Balancing–Not Working Juniper Switching EX-4200
I recently ran into a problem where MS NLB would converge the 2 node web cluster but would not respond to packets. the two nodes were VM’s on a 2008 R2 Hyper-V Cluster. If you moved the nodes to the same Parent Partition they would respond to traffic if the traffic was generated on the same virtual switch.
Went through the normal troubleshooting to make sure that MAC spoofing was enabled on the vNICs etc.
New to the environment was a Juniper EX-4200 Virtual Chassis the switch has IGMP-snooping enabled by default.
the NLB was setup to use a single vNIC with Multicast and IGMP, however the juniper switch was required to disable IGMP-snooping in order to allow unicast traffic to the multicast address.
The NLB IP address on the servers is assigned a Multicast address however the MAC is used for unicast traffic, the juniper switch was blocking the MAC address from entering the Layer2 forwarding table as it assumed it was a multicast packet form the MAC address.
Once we disabled IGMP-snooping on the transit switch the NLB IP was allowed to pass through the Juniper switch, however the confusing part is the MAC address never showed up in any of the forwarding tables of either the Cisco or Juniper Switches, how ever it did pass the traffic.
to disable IGMP-snooping on the EX switches use this command
set protocols igmp-snooping vlan <vLAN Name> disable
commit sync and-quit
the protocol config should look like this
protocols {
igmp-snooping {
vlan vlan-name {
disable;
}
}
}
PowerConnect 8024F 部分設定指令
interface ethernet 1/xg1
storm-control broadcast
storm-control multicast
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 10
exit
!
interface ethernet 1/xg2
storm-control broadcast
storm-control multicast
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 10
exit
!
interface ethernet 1/xg3
storm-control broadcast
storm-control multicast
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 10
exit
!
interface ethernet 1/xg4
storm-control broadcast
storm-control multicast
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 10
exit
!
interface ethernet 1/xg5
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 10
exit
!
interface ethernet 1/xg6
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg7
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg8
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg9
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg10
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg11
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg12
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg13
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg14
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg15
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg16
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg17
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg18
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg19
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg20
spanning-tree cost 2000
spanning-tree portfast
spanning-tree mst 0 external-cost 2000
mtu 9216
switchport access vlan 99
exit
!
interface ethernet 1/xg21
channel-group 12 mode auto
spanning-tree portfast
mtu 9216
switchport mode trunk
exit
!
interface ethernet 1/xg22
channel-group 12 mode auto
spanning-tree portfast
mtu 9216
switchport mode trunk
exit
!
interface ethernet 1/xg23
channel-group 12 mode auto
spanning-tree portfast
mtu 9216
switchport mode trunk
exit
!
interface ethernet 1/xg24
channel-group 12 mode auto
spanning-tree portfast
mtu 9216
switchport mode trunk
exit
!
interface port-channel 1
spanning-tree portfast
switchport mode trunk
mtu 9216
exit
!
interface port-channel 2
spanning-tree portfast
mtu 9216
exit
!
interface port-channel 3
spanning-tree portfast
exit
!
interface port-channel 4
spanning-tree portfast
exit
!
interface port-channel 5
spanning-tree portfast
exit
!
interface port-channel 6
spanning-tree portfast
exit
!
interface port-channel 7
spanning-tree portfast
exit
!
interface port-channel 8
spanning-tree portfast
exit
!
interface port-channel 9
spanning-tree portfast
exit
!
interface port-channel 10
spanning-tree portfast
exit
!
interface port-channel 11
spanning-tree portfast
exit
!
interface port-channel 12
spanning-tree cost 500
spanning-tree portfast
spanning-tree mst 0 external-cost 500
switchport access vlan 10
mtu 9216
exit
interface out-of-band
ip address 192.168.2.239 255.255.255.0 0.0.0.0
exit
dell switch 配置
Applies To:
Switch(es) – PowerConnect 62xx/8024/8024F
Storage Platform(s) – Dell EqualLogic PS Series, Dell PowerVault MD32xxi/MD36xxi
Author:
Naveen Iyengar
Problem:
How to configure the recommended switch settings for IP-SAN?
Solution:
This article provides guidance on how to configure the recommended settings on the Dell PowerConnect switches for IP-SAN environments consisting of Dell EqualLogic or Dell PowerVault MD32xxi/MD36xxi iSCSI Storage arrays.
NOTE:
Dell strongly recommends using dedicated switches for iSCSI traffic.
PowerConnect 62xx/8024/8024F Switch Configuration
The switch must be placed in “privileged” mode to perform the recommended configuration steps. Use the following command to enter “privileged” mode:
console> enable
console#
NOTE:
One may be prompted for a password after submitting the enabled command.
The switch must be placed into configuration mode before any configuration steps can be performed. To enter configuration mode, the following command must be entered:
console# configure
console(config)#
The instructions in this article provide the Command Line Interface (CLI) commands for configuring a PowerConnect switch. Refer to Dell’s support website for the latest documentation if the web-interface is preferred.
The instructions in this article provide the Command Line Interface (CLI) commands for configuring a PowerConnect switch. Refer to Dell’s support website for the latest documentation if the web-interface is preferred.
Interface Naming Convention
The conventions for naming interfaces on Dell PowerConnect 62xx/8024/8024F family of switches are as follows:
Unit#/Interface ID — each interface is identified by the Unit# followed by a / symbol and then the Interface ID (see below). For example, 2/g10 identifies gigabit port 10 within the second unit of a stack.
Unit# — the unit number is used only in a stacking solution where a number of switches are stacked to form a virtual device. In this case, the unit number identifies the physical device identifier within the stack.
Interface ID — is formed by the interface type followed by the interface number. There is currently a predefined list of interface types (see below). If additional interface types are to be defined, they must be registered with Dell. For example, 2/g10 identifies the gigabit port 10 on the second unit.
Interface Types — the following interface types are defined in the 62xx/8024/8024F series switches:
g — gigabit Ethernet port (for example, 1/g2 is the gigabit Ethernet port 2).
g — 10 Gigabit Ethernet port (for example, 1/xg2 is the 10 gigabit Ethernet port 2).
Enabling the PortFast Option to Configure Spanning-Tree Protocol (STP) Edge Ports
It is recommended that you disable spanning-tree protocol (STP) on the switch ports that connect end nodes (iSCSI initiators and storage array network interfaces). If you still decide to enable STP on those switch ports, then you should turn on the STP FastPort feature on the ports in order to allow immediate transition of the ports into a forwarding state. PortFast immediately transitions the port into STP forwarding mode upon linkup. The port still participates in STP. However, if the port is to be a part of the loop, the port eventually transitions into STP blocking mode.
NOTE:
PowerConnect Switches default to RSTP (Rapid Spanning Tree Protocol) an evolution in STP that provides for faster Spanning tree convergence and is preferable to STP
To enable the Rapid Spanning Tree Protocol (RSTP):
console> enable
console# configure
console(config)# spanning-tree mode rstp
To enable PortFast, the spanning-tree PortFast command must be used. The following steps are an example of using this command to enable PortFast:
The following steps are an example of using this command to enable PortFast on a single port – Port 10 of PC8024 Switch #1 in a stack:
console> enable
console# configure
console(config)# interface ethernet 1/xg10
console(config-if-1/xg10)# spanning-tree portfast
console(config-if-1/xg10)# end
console# copy running-config startup-config
console# exit
The following steps are an example of how to enable PortFast on all ports in a PowerConnect 62xx/8024/8024F switch stack:
console> enable
console# configure
console(config)# interface range ethernet all
console(config-if)# spanning-tree portfast
console(config-if)# end
console# copy running-config startup-config
console# exit
Configuring Flow Control
Flow control on the PowerConnect 62xx Family of switches is off by default. To enable flow control on all ports in the switch, use the flowcontrol command.
NOTE:
Flow Control on the PowerConnect 8024/8024F switches are enabled by default
To enable flow control on all ports of a PowerConnect 6248, enter the following commands:
console> enable
console# configure
console(config)# flowcontrol
console(config)# exit
console# copy running-config startup-config
console# exit
NOTE:
Dell PowerVault MD32xxi/MD36xxi and Dell EqualLogic storage arrays will autoconfigure to the switch when Flow Control is turned on.
Configuring Storm Control
A traffic “storm” occurs when a large outpouring of packets creates excessive network traffic that degrades network performance. Many switches have traffic storm control features that prevent ports from being disrupted by broadcast, multicast, or unicast traffic storms on physical interfaces. These features typically work by discarding network packets when the traffic on an interface reaches a percentage of the overall load (usually 80 percent, by default).
Since iSCSI traffic is unicast traffic and can typically utilize the entire link, it is recommended that you disable unicast storm control on switches that handle iSCSI traffic in order to prevent any loss of packets. However, the use of broadcast and multicast storm control is encouraged.
The following steps are an example of using the commands to disable unicast and enable multicast/broadcast storm control on a single port – Port 10 of PC6248 Switch #3 in a stack:
console> enable
console# configure
console(config)# interface ethernet 3/g10
console(config-if-3/g10)# no storm-control unicast
console(config-if-3/g10)# storm-control multicast
console(config-if-3/g10)# storm-control broadcast
console(config-if-3/g10)# end
console# copy running-config startup-config
console# exit
The following steps are an example of how to configure the storm control on all ports in a PowerConnect 62xx/8024/8024F switch:
console> enable
console# configure
console(config)# interface range ethernet all
console(config-if)# no storm-control unicast
console(config-if)# storm-control multicast
console(config-if)# storm-control broadcast
console(config-if)# end
console# copy running-config startup-config
console# exit
Configuring Jumbo Frames
Dell recommends that you enable jumbo frames on the switch ports that handle iSCSI traffic. Jumbo frames are not enabled by default. To enable jumbo frames on the Powerconnect 62xx/8024/8024F switch, use the MTU interface configuration command with a parameter of 9216.
The following steps are an example of using the commands to enable the jumbo frame on one specific port – Port 10 of PC8024 Switch #1 in a stack:
console> enable
console# configure
console(config)# interface ethernet 1/xg1
console(config-if-1/xg1)# mtu 9216
console(config-if-1/xg1)# end
console# copy running-config startup-config
console# exit
The following steps are an example of how to configure the jumbo frame on all ports in a PowerConnect 62xx/8024/8024F switch:
console> enable
console# configure
console(config)# interface range ethernet all
console(config-if)# mtu 9216
console(config-if)# end
console# copy running-config startup-config
console# exit
NOTE:
Jumbo frames must be enabled throughout the entire iSCSI SAN from the NICs, Switches, and storage array ports, otherwise, behavior may be inconsistent.
NOTE:
If jumbo frames are correctly enabled throughout the iSCSI SAN fabric then Dell PowerVault MD32xxi/MD36xxi and Dell EqualLogic storage arrays will autoconfigure to handle jumbo frames. As a result, no jumbo frame configuration is required to be done on these storage arrays.
Configuring Link Aggregated Group (LAG)
When you have two or more Ethernet switches for iSCSI traffic it is recommended to a create Link Aggregated Group (LAG) by having Interswitch Links (ISLs) for redundancy, performance and better scalability.
The number of connections or Ethernet ports in the LAG per switch should ideally be equal to the number of active Ethernet interfaces on all iSCSI storage arrays connected to the switch. For example, if you have two switches connected to two arrays, and each switch has two active array network connections, the LAG should ideally be an aggregate of at least four Ethernet ports.
NOTE:
A stacking bus is strongly recommeneded if a large number of available ports will be used for the LAG or the available ports are at a premium.
The following steps are an example of how to configure the LAG that consists of four ports – ports 21-24 that are linked between two PowerConnect 8024 switches. It is required to enable the jumbo frames on the LAG.
Switch 1:
console> enable
console# configure
console(config)# interface range ethernet 1/xg21-1/xg24
console(config-if)# channel-group 1 mode on
console(config-if)# mtu 9216
console(config-if)# exit
console(config)# interface port-channel 1
console(config-if-ch1)# mtu 9216
console(config-if-ch1)# end
console# copy running-config startup-config
console# exit
Switch 2:
console> enable
console# configure
console(config)# interface range ethernet 1/xg21-1/xg24
console(config-if)# channel-group 1 mode on
console(config-if)# mtu 9216
console(config-if)# exit
console(config)# interface port-channel 1
console(config-if-ch1)# mtu 9216
console(config-if-ch1)# end
console# copy running-config startup-config
console# exit
vmware esx 操作命令
1：看你的esx版本。
vmware -v
2：列出esx里知道的服务
esxcfg-firewall -s
3：查看具体服务的情况
esxcfg-firewall -q sshclinet
4：重新启动vmware服务
service mgmt-vmware restart
5: 修改root的密码
passwd root
6：列出你当前的虚拟交换机
esxcfg-vswitch -l
7：查看控制台的设置
esxcfg-vswif -l
8：列出系统的网卡
esxcfg-nics -l
9：添加一个虚拟交换机，名字叫（internal）连接到两块物理网卡，（重新启动服务，vi就能看见了）
esxcfg-vswitch -a vSwitch1
esxcfg-vswitch -A internal vSwitch1
esxcfg-vswitch -L vmnic1 vSwitch1
esxcfg-vswitch -L vmnic2 vSwitch1
10：删除交换机,(注意，别把控制台的交换机也删了）
esxcfg-vswitch -D vSwitch1
11：删除交换机上的网卡
esxcfg-vswitch -u vmnic1 vswitch2
12：删除portgroup
esxcfg-vswitch -D internel vswitch1
13：创建 vmkernel switch ，如果你希望使用vmotion，iscsi的这些功能，你必须创建( 通常是不需要添加网关的）
esxcfg-vswitch -l
esxcfg-vswitch -a vswitch2
esxcfg-vswitch -A “vm kernel” vswitch2
esxcfg-vswitch -L vmnic3 vswitch2
esxcfg-vmknic -a “vm kernel” -i 172.16.1.141 -n 255.255.252.0
esxcfg-route 172.16.0.254
14：打开防火墙ssh端口
esxcfg-firewall -e sshclient
esxcfg-firewall -d sshclient
15: 创建控制台
esxcfg-vswitch -a vSwitch0
esxcfg-vswitch -A “service console” vSwitch0
esxcfg-vswitch -L vmnic0 vSwitch0
esxcfg-vswif -a vswif0 -p “service console” -i 172.16.1.140 -n 255.255.252.0
16: 添加nas设备(a 添加标签，-o，是nas服务器的名字或ip，-s 是nas输入的共享名字）
esxcfg-nas -a isos -o nas.vmwar.cn -s isos
17：列出nas连接
esxcfg-nas -l
18: 强迫esx去连接nas服务器(用esxcfg-nas -l 来看看结果）
esxcfg-nas -r
esxcfg-nas -l
19：连接iscsi 设备(e:enable q:查询 d：disable s:强迫搜索）
esxcfg-swiscsi -e
20：设置targetip
vmkiscsi-tool -D -a 172.16.1.133 vmhba40
21：列出和target的连接
vmkiscsi-tool -l -T vmhba40
22：列出当前的磁盘
ls -l /vmfs/devices/disks
How to change the IP address:
1) From the VI Client 2) From the Physcial Console Connection
See the following sections for details on each method.
From the VI Client
Using the Virtual Infrastructure Client, the DNS information (Configuration tab > DNS and Routing) can be changed on the fly. Similarly, the gateway address (routing subtab of the DNS and Routing window) and the hostname (DNS Configuration subtab of DNS and Routing) can be changed through the user interface. Hostname and domain changes through the VI Client do not take place until the ESX host is rebooted.
From the Physical Console Connection
Changing the IP for the service console must be done from a physical console connection, either at the host, through a KVM or other remote console connection. If you make changes through a network connection such as SSH, network connectivity to the service console will disconnect because the service console’s network interface will change.
For this example, it is assumed that vswif0 is the service console adapter that is the interface to which to apply the IP address change. Running the command
esxcfg-vswif -i x.x.x.x vswif0
will set the IP address to the value substituted for x.x.x.x in the command. You will need to edit the /etc/hosts file and change it so that it reflects the new IP address in use for the service console.
The gateway address and hostname are in /etc/sysconfig/network.
After you edit these files, you must reboot the host or restart the network service using the following command:
service network restart
Note: This command breaks any current network connections to the service console.
You can also dynamically change the host name using the command:
hostname newname
Note: This command creates a temporary host name change. This change is lost when the system is rebooted.
To change the DNS server settings, edit the /etc/resolv.conf file and update the nameserver IPs and search domain if applicable.
2012 春晚节目单
随着央视春晚第一次联排的进行，昨日，春晚节目单被部分媒体曝光。费翔、韦唯、蔡国庆等久未露面的歌手将登上春晚的舞台，此外，语言类节目仅剩8个，其中包括2个相声和6个小品。据了解，这只是一份暂定节目单，不排除在直播当天有节目被撤换的可能。
上半场节目单
(最终节目内容及顺序以除夕当晚为准)
1.开场曲
2.童谣 表演者：邓鸣贺
主持人《东西南北大拜年》之《欢乐中国年》
3.歌曲《新春拜年歌》
4.创意钢琴《金蛇狂舞》 《龙的传人》 表演者：王力宏、李云迪等
5.小品《小合唱》 表演者：周炜、吕继宏等
6.绛州鼓乐 《鼓韵龙腾》
7.创意儿童节目 《除夕的传说》 表演者： 韩庚
8.歌曲《万物生》表演者： 萨顶顶
9.相声《奋斗》表演者：曹云金、刘云天
10.舞蹈《龙凤呈祥》
11.小品《天网恢恢》 表演者：蔡明等四人
12.短片《回家过年》
13.歌曲《好久没回家》表演者： 陈坤
14.歌曲《叫一声爸妈》表演者： 宋祖英
15.杂技《空山竹影》
16.小品《荆轲刺秦》表演者：黄宏、邵峰、沙溢等
17.互动魔术 表演者： 董卿、刘谦
18.民族歌舞《追爱》表演者： 雷佳等
19.小品《我们的幸福》
20.爱情歌曲联唱之《今天你要嫁给我》 、《婚誓》、《牵手》 表演者：夏雨、袁泉等
21.歌曲《因为爱情》表演者：王菲、陈奕迅
22.小品《爱的代码》表演者： 冯巩等
23.歌曲《把幸福给你》表演者： 孙楠
24.戏曲节目《戏迷一家亲》 表演者：刘佩琦等
25.小品《面试》 表演者： 郭冬临、魏积安
26.机器人舞蹈《玩具总动员》
27.舞蹈《天鹅湖》
28.短片《春晚记忆》
下半场 节目单
29.歌曲《致敬三十年》
《冬天里的一把火》
表演者：金美儿
《故乡的云》 表演者：费翔
《爱的奉献》 表演者：韦唯、吴秀波
《常回家看看》 表演者：蔡国庆、王珞丹
《前门情思大碗茶》 表演者：李谷一
《新贵妃醉酒》表演者：李玉刚
《我的中国心》表演者：张明敏
30.舞蹈《雀之恋》表演者：杨丽萍等
31.歌曲《大爱》表演者：刘欢
32.赵本山小品
33.歌曲《好人就在身边》 表演者：谭晶
34.舞蹈《冰凌神舞》
35.歌曲《思乡曲》 表演者：蒋大为、朱之文
36.歌曲《远方的家》 表演者：张也
37.主持人串场及零点拜年仪式
表演者：主持人、冯绍峰、阿Sa
38.歌曲《中国美》表演者：玖月奇迹
39.杂技音乐剧《年夜饭》 表演者：洪剑涛等
40.水晶球表演 表演者：胡启志
41.结束曲《天下一家》
sd卡内存真假识别
对sd卡做真假识别之前，要先了解你的sd卡，先要知道你买的卡是那个类别
将sd卡在电脑上格式化，然后copy一个超过1G的文件到sd上，就可以看到sd卡速度，
我的是class4 sony sd，速度5M/s
2012深圳迎春花市
2012 罗湖迎春花市
深圳市迎春花市时间：2012年1月18日-2012年1月22日
深圳市迎春花市地点：罗湖区爱国路段
深圳市迎春花市交通：由于花市举办地点全线封闭，市民可乘车到文锦中路或东门北路步行
深圳市迎春花市停车位：将在东门北路、怡景路、爱国路等路段设置
深圳市迎春花市分布：本届迎春花市铺位类别分为A、B、C、D、E、F、G、H八个区。其中A、B、C、D区为花木区(共512个铺位，其中A区144个、B区130个、C区130个、D区108个)，摆放盆花、鲜花、盆景、根雕等园林园艺产品;E区为花艺工艺品区(共115个铺位);F、G区为珠宝、玩具、精品饰物区(共270个铺位，其中F区135个、G区135个);H区为春联、美术品、书画艺术品、文具区(共129个铺位)。
2012南山迎春花市
南山迎春花市时间：2012年1月16日-2012年1月22日
南山迎春花市地点：F1摩托艇赛场停车场
南山迎春花市分会场：
1.荷兰花卉风情小镇(举办精品兰花展销，主要销售热带兰花品种，包括蝴蝶兰、卡特兰、石斛兰等)
2.沙河西路同发路口以西的“十里花卉长廊”
2012宝安迎春花市
宝安迎春花市时间：2012年1月18日-2012年1月22日
宝安迎春花市地点：宝安中心区金科路(海秀路至罗田路段)
宝安迎春花市销售品种：有大花惠兰、蝴蝶兰、君子兰等高档兰花，有火炬、红星、牡丹、海棠、水仙、百合和各种年桔等喜庆年花，还有金钱树、发财树、富贵树、铁树等室内常绿植物，品种有上百种之多。
个性qrcode生成，QRhacker
QR码已被越来越多的智能手机和科技公司所采用，逐渐成为企业和产品品牌的主流应用。然而一般的QR码看起来都不是很美观，很多时候甚至会让人看了厌烦。QRhacker则提供了一种更为便捷和个性化的QR码生成方式，而且它不需要你有任何Photoshop技术。
QRhacker的使用方法很简单：
和一般的QR码服务一样，QRhacker可以帮助你为文本、URL、电话号码和联系人信息生成QR码，你首先需要选择生成服务类型。
接 着你就可以对QR码进行个性化的设置。你可以将QR码边缘设置成弧形，任意选择背景颜色和前景颜色，甚至可以在背景中插入图片。如果你想利用QR码进行品 牌宣传，你还可以将公司的Logo嵌入其中。此外，你还可以利用Pixel像素模式功能对QR码的颜色进行逐块编辑，过程就像在帆布上绘画一样有趣。
此外，QRhacker还设有设置进展提示，提醒你不要将QR码设计得太复杂，导致无法识别。
完成QR码设计后，你可以将其保存为PDF或PNG格式。
vnc，teamviewer，logmein的比较
1.vnc
vnc有ultravnc,realvnc等多种，vnc主要是通过点对点通信，主要用于内网或者vpn网络，或者能nat转发的外网
vnc的优点的访问简单，只要知道对方的vnc密码，就可以访问
2.teamviewer
teamviewer是一个可以远程控制内网的软件，只要你下载teamviewer客户端，运行之后会从服务器自动得到ID号，
互链网上其他电脑，可以通过id号，穿越局域网访问你的电脑，主要用于远程维护类
3.logmein
在http://www.logmein.com注册帐号后，然后在本地机上安装客户端，你就可以随时随地登录logmein的网站，来管理你的
计算机。