Learn something interesting ~
Beat generation 垮掉的一代
Tea-ceremony 茶道
Badger game 美人计
Scene stealer 抢镜头的人
Hooligan 阿飞，足球流氓
Repeated offender 惯犯
Double agent 双重间谍
Mr. Big 黑社会老大
Love child 私生子
Hand-to-hand fighting 肉搏
Box news 花边新闻
Screen agers 整天看电视玩电脑的孩子
June-December wedding 双方年龄悬殊的婚姻
King’s English 标准英语
Leap day/year 闰日2.29/年366
Maid of Orleans 圣女贞德
Narrow squeak（口）九死一生的脱险
Ninja turtle 忍者神龟
Poet laureate 桂冠诗人
Ponytail 马尾辫
Protestant 新教徒
Pulitzer Prize 普利策奖
Rat race 激烈的竞争
Red-light district 红灯区
Reader’s Digest 读者文摘
Russian roulette 俄罗斯轮盘赌
Sexual harassment 性骚扰
Short fuse 易怒的脾气
Soft-soap 奉承讨好
Silent contribution 隐名捐款
Silly money 来路不明的钱
Silver screen 银幕，电影界
Summer complaint 夏季病，拉肚子
Tenth-rate 最低等的，劣等的
Vertical/lateral thinking 纵向，横向思维
Wide-body 大部头的作品
Wheel of life （佛教）轮回
Xenomania 媚外
Yearbook 年鉴年刊
Zen 禅
Paparazzi 狗仔队
Show people 娱乐界人士
Exotic dance 脱衣舞
Bearish 行情下跌的
Bullish 行情上涨的
State prisoner 政治犯
Stowaway 偷渡者，逃票的乘客
Plainclothesman 便衣警察
Police dog 警犬
Police post 派出所
Negligent homicide 过失杀人
Impostor 江湖骗子
ICJ International Court of Justice 国际法院
Espionage 间谍 间谍活动
Lifer 职业军人
Mine 地雷 水雷
Panzer 装甲车 坦克
Off limits 军事禁区
Q-boat 伪装成商船或渔船的武装船只
Riot corps 防暴部队
Standing army 常规军
Sniper 狙击手
Bermuda Triangle 百慕大三角洲
Brain drain 脑力人才外流
Brawn drain 劳力外流
Break- dancing 霹雳舞
French windows 落地窗
Funeral home 殡仪馆
Taillight 车尾灯
Visiting team 客队
Runner-up 亚军
Black referee 黑哨
Foul play 犯规动作
Standing broad jump 立定跳远
Underachiever 差等生
Hothouse 对儿童进行学前教育
Whiz kid 神童 优等生
Newsbreak 重要新闻
Needle trade 成衣业
Massage parlour 挂按摩牌子的妓院
Moonlight 作动词，干第二职业
Mixed marriage 异族通婚
Moon roof 汽车的顶窗
Egghead 对知识分子的蔑称
Dog days 七八月份的酷暑期，伏天
Connoisseur 鉴赏家
Box office 票房
Bridesmaid 女傧相
Bee （美）为互助友好而举行的聚会
Bigtime 红极一时的，赫赫有名的
Bank of issue 发行银行
Cater ∏ 美国总统克林顿 （卡特二世。。。）
Big stick大棒政策
Oxbridge 牛津和剑桥大学
Multiversity 综合大学
CDV compact video disc 激光光碟
Beeper BP机
Exclusive 独家新闻
Divorcee 离了婚的人
disposable worker 临时工
Eden 伊甸园
Bandwagon 见风使舵
Sapphire 蓝宝石
Scrappage 报废物
Shangri-la 香格里拉
Obituary 补告
Hangover 宿醉
Full scholarship 全额奖学金
Stone-cold fox 冰山美人
Brain trust 政府的智囊团
A-list 名流群，精英
all-expense tour 自费游
Bard-of-Avon 埃文河诗人，莎士比亚的别称
Beau monde 上流社会
Beautiful people 上流社会的时髦阶层
Bagstuffer 街头广告传单
Antichoice 反堕胎
Backwater 死水，死气沉沉的地方
Intercom 对讲机，闭路通讯装置
In vitro fertilization 体外受精，试管受精
Cottonmouth snake 百步蛇
Laser surgery 激光外科手术
Intercept 截球
Unscrupulous bombing 狂轰滥炸
Tommy gun (美)冲锋枪
Strafe 扫射，猛烈炮击
Superbomb 氢弹
Unconditional surrender 无条件投降
Losing battle 必败之战
Military operation 作战
Missile equipped destroyer 导弹驱逐舰
Mess 军用食堂
Rock-bottom 最低的
Seed money 本钱
Principal 本金，可生息
Securities 证券，有价证券
Sag 萧条，下跌
Profiteer 投机商，奸商
Prime 银行贷款的最低利率
Red ink 赤字，亏损
Ready money 现钞
Bell-bottom trousers 喇叭裤
Julibee 五十周年大庆
Jim Crow 对黑人的蔑称
Iron lady 指铁娘子撒切尔夫人
Itinerant 巡回的
Intelligentsia知识分子的总称，知识界，知识阶层
Jack 千斤顶
Blue moon 千载难逢的时机
Benefit 义卖，义演，义赛
Brainwave 灵感，突然想到的主意
Honor man （美）优等生
Full professor 正教授
Doctorate博士学位
Alma Mater 母校
Academician 院士
Pony report 每日要闻报道
Peter Funk （美俚）拍卖中冒充卖家抬高价格的冒牌出价人
Pep rally 动员大会
Pipe dream 白日梦，空想
Pay TV 收费电视
Plastic operation 整形手术
Made man 成功的人
Manicure 修指甲
Mad money （美俚）私房钱
Lotusland 逍遥乡
Jolly Roger 海盗旗
Invalid 病号，伤残者
Informed sources 消息灵通的人士
Hot air 吹牛，空话
Idiot box （口）电视机
Ins and outs 迂回曲折，底细
In-flight meal 航空餐
Network Troubleshooting using Command-line
To troubleshoot a TCP/IP networking problem, utilize the following command step be step.
- Reference: Network Command-line utilities, http://www.grape-info.com/doc/win2000srv/network/netcommand.html
1. ipconfig
ipconfig /all : view TCP/IP configuration of the computer.
ipconfig /renew : force network adapter to contact a DHCP server and renew the existing configuration or obtain a new configuration.
Also, ipconfig command can be used to deal with DNS. (might be useful) /displaydns : displays the contents of the DNS Resolver Cache; /flushdns : purges the DNS cache; /registerdns : refreshes all DHCP leases and re-registers DNS names.
2. ping
The ping command helps to verify IP-level connectivity by sending an ICMP echo request to a target host name or IP address.
Perform the following steps when using ping:
1). Ping the loopback address to verify that TCP/IP is installed and configured correctly on the local computer.
ping 127.0.0.1
2). Ping the IP address of the local computer to verify that it was added to the network correctly.
ping IP_address_of_local_host
3). Ping the IP address of the default gateway to verify that default gateway is functioning and you can communicate with a local host on the local network.
ping IP_address_of_default_gateway
4). Ping the IP address of a remote host to verify that you can communicate through a router.
ping IP_address_of_remote_host
The ping command uses Windows Sockets - style name resolution to resolve a computer name to an IP address, so if pinging by address succeeds, but pinging by name failes, then the problem lies in address or name resolution, not network connectivity.
3. arp
The arp command is used to view and modify the ARP table entires on the local computer so as to resolve address resolution problems.
4. nbtstat
The nbtstat command is used for troubleshooting NetBIOS name resolution problems (basically for netBIOS services in local area networks).
NetBIOS (Network Basic Input/Output System) provides services related to the session layer of the OSI model allowing applications on seperate computers to commnicate over a local area network. NetBIOS over TCP/IP is a network protocol that allows legacy computer applications relying on NetBIOS API to be used on modern TCP/IP networks. NetBIOS provides three distinct services: name service, session service and datagram distribution service.
5. netstat
The netstat command can be used to display protocol stastics and current TCP/IP connections.
netstat -a : displays all connections.
netstat -r : displays the route table plus active connections.
netstat -e : displays Ethernet statistics.
netstat -s : displays per-protocol statistics.
netstat -n : addresses and port numbers are not converted to names.
6. tracert
Trace Route is a route-tracing utility that is used to determine the path that an IP datagram takes to reach a destination. The tracert command uses the IP time-to-live field and ICMP error messages to determine the route.
tracert [-d](specifies that IP address are not resolved to host name) [-h maximum_hops] [-j host-list] [-w timeout] target_name
7. pathping
The pathping command is a route tracing tool that combines features of the ping and tracert commands with additional information that neither of those tools provides.
The pathping command sends packets to each router on the way to a final destination over a period of time, and then computes results based on the packets returned from each hop. Since the command shows the degree of packet loss at any given router or link, it is easy to determine which routers or links might be causing network problems.
802.11 Trace File Analysis in NS2
1. 802.11 trace file format
NS2中802.11的trace功能利用cmu-trace对象来实现，并建议了一种新的trace格式，这种新格式目前是适用于无线网模拟，并且向前与老版本的trace格式兼容。下边分别看下新老两种trace格式：
1.1 New trace format
In order to use new trace format, the following command:
$ns use-newtrace
must be called before the universal trace command $ns trace-all
An example of the new trace format is as following:
The new trace format can be divided into following fields:
1). Event type. the first field describes the type of event taking place at the nodeand can be one of the four types:
s - send
r - receive
d - drop
f - forward
2). General tag. The second field starting with "-t" may stand for time or global setting.
-t time
-t * (global setting)
3). Next hop info. This field provides next hop info and the tag starts with a leading "-H".
-Hs: id for this node
-Hd: id for next hop towards the destination.
4). Node property tags. This field denotes the node properties like node-id, the level at which tracing is being done like agent, router or MAC. The tags start with a leading "-N" and are listed as below:
-Ni: node id
-Nx: node’s x-coordinate
-Ny: node’s y-coordinate
-Nz: node’s z-coordinate
-Ne: node energy level
-Nl: trace level, such as AGT, RTR, MAC
-Nw: reason for the event. The different reasons for dropping a packet are given below:
"END" DROP_END_OF_SIMULATION
"COL" DROP_MAC_COLLISION
"DUP" DROP_MAC_DUPLICATE
"ERR" DROP_MAC_PACKET_ERROR
"RET" DROP_MAC_RETRY_COUNT_EXCEEDED
"STA" DROP_MAC_INVALID_STATE
"BSY" DROP_MAC_BUSY
"NRTE" DROP_RTR_NO_ROUTE i.e no route is available.
"LOOP" DROP_RTR_ROUTE_LOOP i.e there is a routing loop
"TTL" DROP_RTR_TTL i.e TTL has reached zero.
"TOUT" DROP_RTR_QTIMEOUT i.e packet has expired.
"CBK" DROP_RTR_MAC_CALLBACK
"IFQ" DROP_IFQ_QFULL i.e no buffer space in IFQ.
"ARP" DROP_IFQ_ARP_FULL i.e dropped by ARP
"OUT" DROP_OUTSIDE_SUBNET i.e dropped by base stations on receiving routing updates from nodes outside its domain.
5). Packet info at MAC level. This field gives MAC layer information and starts with a leading "-M" as shown below:
-Ma: duration
-Md: dst’s ethernet address
-Ms: src’s ethernet address
-Mt: ethernet type
6). Packet information at IP level. The tags for this field start with a leading "-I" and are listed along with their explanations asfollowing:
-Is: source address.source port number
-Id: dest address.dest port number
-It: packet type
-Il: packet size
-If: flow id
-Ii: unique id
-Iv: ttl value
7). Packet info at "Application level". The packet information at application level consists of the type of application like ARP,TCP, the type of adhoc routing protocol like DSDV, DSR, AODV etc being traced. This field consists of a leading "-P" and list of tags for different application is listed as below:
-P arp Address Resolution Protocol. Details for ARP is given by the following tags:
-Po: ARP Request/Reply
-Pm: src mac address
-Ps: src address
-Pa: dst mac address
-Pd: dst address
-P dsr This denotes the adhoc routing protocol called Dynamic source routing. Information on DSR is represented bythe following tags:
-Pn: how many nodes traversed
-Pq: routing request flag
-Pi: route request sequence number
-Pp: routing reply flag
-Pl: reply length
-Pe: src of srcrouting->dst of the source routing
-Pw: error report flag ?
-Pm: number of errors
-Pc: report to whom
-Pb: link error from linka->linkb
-P cbr Constant bit rate. Information about the CBR application is represented by the following tags:
-Pi: sequence number
-Pf: how many times this pkt was forwarded
-Po: optimal number of forwards
-P tcp Information about TCP flow is given by the following subtags:
-Ps: seq number
-Pa: ack number
-Pf: how many times this pkt was forwarded
-Po: optimal number of forwards
This field is still under development and new tags shall be added for other applications as they get included along theway.
1.2 Old trace format
NS2中802.11的trace功能利用cmu-trace对象来实现，并建议了一种新的trace格式，这种新格式目前是适用于无线网模拟，并且向前与老版本的trace格式兼容。下边分别看下新老两种trace格式：
1.1 New trace format
In order to use new trace format, the following command:
$ns use-newtrace
must be called before the universal trace command $ns trace-all
An example of the new trace format is as following:
The new trace format can be divided into following fields:
1). Event type. the first field describes the type of event taking place at the nodeand can be one of the four types:
s - send
r - receive
d - drop
f - forward
2). General tag. The second field starting with "-t" may stand for time or global setting.
-t time
-t * (global setting)
3). Next hop info. This field provides next hop info and the tag starts with a leading "-H".
-Hs: id for this node
-Hd: id for next hop towards the destination.
4). Node property tags. This field denotes the node properties like node-id, the level at which tracing is being done like agent, router or MAC. The tags start with a leading "-N" and are listed as below:
-Ni: node id
-Nx: node’s x-coordinate
-Ny: node’s y-coordinate
-Nz: node’s z-coordinate
-Ne: node energy level
-Nl: trace level, such as AGT, RTR, MAC
-Nw: reason for the event. The different reasons for dropping a packet are given below:
"END" DROP_END_OF_SIMULATION
"COL" DROP_MAC_COLLISION
"DUP" DROP_MAC_DUPLICATE
"ERR" DROP_MAC_PACKET_ERROR
"RET" DROP_MAC_RETRY_COUNT_EXCEEDED
"STA" DROP_MAC_INVALID_STATE
"BSY" DROP_MAC_BUSY
"NRTE" DROP_RTR_NO_ROUTE i.e no route is available.
"LOOP" DROP_RTR_ROUTE_LOOP i.e there is a routing loop
"TTL" DROP_RTR_TTL i.e TTL has reached zero.
"TOUT" DROP_RTR_QTIMEOUT i.e packet has expired.
"CBK" DROP_RTR_MAC_CALLBACK
"IFQ" DROP_IFQ_QFULL i.e no buffer space in IFQ.
"ARP" DROP_IFQ_ARP_FULL i.e dropped by ARP
"OUT" DROP_OUTSIDE_SUBNET i.e dropped by base stations on receiving routing updates from nodes outside its domain.
5). Packet info at MAC level. This field gives MAC layer information and starts with a leading "-M" as shown below:
-Ma: duration
-Md: dst’s ethernet address
-Ms: src’s ethernet address
-Mt: ethernet type
6). Packet information at IP level. The tags for this field start with a leading "-I" and are listed along with their explanations asfollowing:
-Is: source address.source port number
-Id: dest address.dest port number
-It: packet type
-Il: packet size
-If: flow id
-Ii: unique id
-Iv: ttl value
7). Packet info at "Application level". The packet information at application level consists of the type of application like ARP,TCP, the type of adhoc routing protocol like DSDV, DSR, AODV etc being traced. This field consists of a leading "-P" and list of tags for different application is listed as below:
-P arp Address Resolution Protocol. Details for ARP is given by the following tags:
-Po: ARP Request/Reply
-Pm: src mac address
-Ps: src address
-Pa: dst mac address
-Pd: dst address
-P dsr This denotes the adhoc routing protocol called Dynamic source routing. Information on DSR is represented bythe following tags:
-Pn: how many nodes traversed
-Pq: routing request flag
-Pi: route request sequence number
-Pp: routing reply flag
-Pl: reply length
-Pe: src of srcrouting->dst of the source routing
-Pw: error report flag ?
-Pm: number of errors
-Pc: report to whom
-Pb: link error from linka->linkb
-P cbr Constant bit rate. Information about the CBR application is represented by the following tags:
-Pi: sequence number
-Pf: how many times this pkt was forwarded
-Po: optimal number of forwards
-P tcp Information about TCP flow is given by the following subtags:
-Ps: seq number
-Pa: ack number
-Pf: how many times this pkt was forwarded
-Po: optimal number of forwards
This field is still under development and new tags shall be added for other applications as they get included along theway.
1.2 Old trace format
By default, NS2 uses old trace format in 802.11 simulation.
An example of the old trace format is as following:
The old trace format can be divided into following fields:
1). ACTION [s r D] s - sent, r - received, D - dropped
2). WHEN: the time when the action happened
3). WHERE: the node where the action happened
4). LAYER: AGT -- application,
RTR -- routing,
LL -- link layer (ARP is done here) ,
IFQ -- outgoing packet queue (between link and mac layer),
MAC -- mac,
PHY -- physical
5). SEQNO: the sequence number of the packet
6). TYPE: the packet type
cbr -- CBR data stream packet
DSR -- DSR routing packet (control packet generated by routing)
RTS -- RTS packet generated by MAC 802.11
ARP -- link layer ARP packet
7). SIZE: the size of packet at current layer, when packet goes down, size increases, goes up size decreases
[a b c d]: a -- the packet duration in mac layer header
b -- the mac address of destination
c -- the mac address of source
d -- the mac type of the packet body
8). flags:
[......]: [
source node ip : port_number
destination node ip (-1 means broadcast) : port_number
ip header ttl
ip of next hop (0 means node 0 or broadcast)
]
2. Analyzing by using perl
3. Tools for trace analysis
cygwin+ns2.33安装过程遇到的问题及解决方法
1. cygwin安装组件的选择
为了简单，我直接选择的是完全安装，但实际上在之后ns2的安装上还是会存在找不到某些必须组件的问题。问题在于选择package的时候，点选了"Hide obsolete packages"的选项，而这些obsolete packages中的一些默认选项是not install，所以即使使用完全安装，也要show obsolete packages，从而确保"完全安装"。当然，也可以按照网上的方法只安装ns2必要的组件，但其中的一些也是位于obsolete packages中的。
2. bash.bashrc文件
按照网络上的说法，安装ns2之后需要把环境变量写入bash文件，而且据说在第一次运行cygwin后会自动在/home/usrname文件夹中生成针对此用户的bash文件。但是在我尝试了两次，并没有在/home/usrname中找到bash，原因未知。
解决方法1：copy系统默认的global bash文件到/home/usrname, 并命名为.bashrc, global bash在/etc/defaults/etc/bash.bashrc。这是网络上提供的方法，我没尝试过。
解决方法2：由于cygwin实际上是单用户的unix模拟环境，所以可以直接修改系统默认的global bash, 即位于/etc文件夹中的bash.bashrc，添加ns2相关路径到此bash文件即可。Attention：为了是修改后的bash文件有效，需要执行source bash.bashrc命令。
3. bash & bash script
Executing commands
为了简单，我直接选择的是完全安装，但实际上在之后ns2的安装上还是会存在找不到某些必须组件的问题。问题在于选择package的时候，点选了"Hide obsolete packages"的选项，而这些obsolete packages中的一些默认选项是not install，所以即使使用完全安装，也要show obsolete packages，从而确保"完全安装"。当然，也可以按照网上的方法只安装ns2必要的组件，但其中的一些也是位于obsolete packages中的。
2. bash.bashrc文件
按照网络上的说法，安装ns2之后需要把环境变量写入bash文件，而且据说在第一次运行cygwin后会自动在/home/usrname文件夹中生成针对此用户的bash文件。但是在我尝试了两次，并没有在/home/usrname中找到bash，原因未知。
解决方法1：copy系统默认的global bash文件到/home/usrname, 并命名为.bashrc, global bash在/etc/defaults/etc/bash.bashrc。这是网络上提供的方法，我没尝试过。
解决方法2：由于cygwin实际上是单用户的unix模拟环境，所以可以直接修改系统默认的global bash, 即位于/etc文件夹中的bash.bashrc，添加ns2相关路径到此bash文件即可。Attention：为了是修改后的bash文件有效，需要执行source bash.bashrc命令。
3. bash & bash script
- Ref: Bash Guide for Beginners: http://tldp.org/LDP/Bash-Beginners-Guide/html/Bash-Beginners-Guide.html#chap_01
Bourne Again shell
The UNIX shell program interprets user commands, which are either directly entered by the user, or which can be read from a file called the shell script or shell program. Shell scripts are interpreted, not compiled.
Apart from passing commands to the kernel, the main task of a shell is providing a user environment, which can be configured individually using shell resource configuration files.
bash or Bourne Again shell: the standard GNU shell, intuitive and flexible. On Linux, bash is the standard shell for common users. Bash offers functions including command line editing, unlimited size command history, job control, shell functions and aliases, indexed arrays of unlimited size, and integer arithmetic in any base from two to sixty-four.Executing commands
Bash determines the type of program that is to be executed. Normal programs are system commands that exist in compiled form on your system. When such a program is executed, a new process is created because Bash makes an exact copy of itself. This child process has the same environment as its parent, only the process ID number is different. This procedure is called forking.
After the forking process, the address space of the child process is overwritten with the new process data. This is done through an exec call to the system.
The fork-and-exec mechanism thus switches an old command with a new, while the environment in which the new program is executed remains the same, including configuration of input and output devices, environment variables and priority. This mechanism is used to create all UNIX processes, so it also applies to the Linux operating system. Even the first process, init, with process ID 1, is forked during the boot procedure in the so-called bootstrapping procedure.
Shell script
Shell scripts consist of three kinds of commands - the shell functions, shell built-ins and existing commands in a directory on your system, which are arranged as shell syntax dictates. Scripts are read and executed line per line and should have a logical structure.
4. 针对ns2.33中nam的问题
安装ns2完成后，运行simple.tcl，nam执行时候会报错：
[code omitted because of length]
: no event type or button # or keysym
while executing
"bind Listbox {
%W yview scroll [expr {- (%D / 120) * 4}] units
}"
invoked from within
"if {[tk windowingsystem] eq "classic" [tk windowingsystem] eq "aqua"} {
bind Listbox {
%W yview scroll [expr {- (%D)}] units
}
bind Li..."
这个是ns2.33特有的一个问题，原因据说是tcl/tk和x11-proto/xproto-7.0.13不兼容,网络上给出两种解决方法：
1. 给tk-8.4.18-tkBind打上补丁，具体来说，到http://bugs.gentoo.org/show_bug.cgi?id=225999 下载 tk-8.4.18-tkBind.patch，放在ns-allinone-2.33目录下，之后运行命令
patch -p0 < tk-8.4.18-tkBind.patch
然后重新编译安装ns2.
2. 直接修改 ns-allinone-2.33/tk8.4.18/generic/tkBind.c 文件如下：
...
static int flagArray [TK_LASTEVENT] = {
...
/*MappingNotify*/ 0,
+#ifdef GenericEvent
+/*GenericEvent*/ 0,
+#endif
/*VirtualEvent*/ VIRTUAL,
...
之后重新编译安装ns2.
我使用了第二种方法,可以解决执行nam时报错的问题。
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