close wait 的快速清理方法

注意：

本方法使用了tcpdump 和 sendip工具，具体的安装和下载自己寻找教程

还是列出来吧：

sendip安装

下载地址： http://www.earth.li/projectpurple/progs/sendip.html

tar zxvf sendip-2.5.tar.gz

cd sendip-2.5

make

make install 

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如果make出现错误：操作如下，没报错直接跳过

cc1: warnings being treated as errors

ipv4.c: In function 'do_opt':

ipv4.c:212: warning: pointer targets inpassing argument 1 of 'sprintf' differ in signedness

ipv4.c:213: warning: pointer targets inpassing argument 1 of 'compact_string' differ in signedness

ipv4.c:240: warning: pointer targets inpassing argument 5 of 'addoption' differ in signedness

ipv4.c:355: warning: pointer targets inpassing argument 5 of 'addoption' differ in signedness

ipv4.c:380: warning: pointer targets inpassing argument 5 of 'addoption' differ in signedness

ipv4.c:402: warning: pointer targets inpassing argument 5 of 'addoption' differ in signedness

make: *** [ipv4.so] Error 1

提示上述warning被作为错误

我们打开ipv4.c文件，找到各行，如212行：sprintf(data,"0x%s",arg);

发现参数data在前面（207行）声明为u_int8_t *类型，而sprintf的参数一般为（char *）而得到data的变量arg也是char *类型的，于是我们在212行将参数data显示转换为char *类型：sprintf((char *)data,"0x%s",arg);

再次make发现212行warning消失，于是其213几行和同样处理。

在240、355、380、402行方法'addoption'的data的参数是char *类型，但我们发现386行的addoption方法第5个参数为u_int8_t *类型，于是我们将上面几行的data显示转换为u_int8_t *类型，如240行：addoption(0,0,7,len+2,(u_int8_t *)data,pack);

再次make发现ipv4.c中的warning已经消失，但是出现tcp.c文件中的若干warning：

cc1: warnings being treated as errors

tcp.c: In function 'do_opt':

tcp.c:207: warning: pointer targets inpassing argument 1 of 'sprintf' differ in signedness

tcp.c:208: warning: pointer targets inpassing argument 1 of 'compact_string' differ in signedness

tcp.c:239: warning: pointer targets inassignment differ in signedness

tcp.c:241: warning: pointer targets inpassing argument 1 of 'strchr' differ in signedness

tcp.c:241: warning: pointer targets inassignment differ in signedness

tcp.c:249: warning: pointer targets inassignment differ in signedness

tcp.c:252: warning: pointer targets inassignment differ in signedness

tcp.c:262: warning: pointer targets inassignment differ in signedness

tcp.c:264: warning: pointer targets inassignment differ in signedness

tcp.c:266: warning: pointer targets in assignmentdiffer in signedness

tcp.c:270: warning: pointer targets inassignment differ in signedness

make: *** [tcp.so] Error 1

我们以类似的方法找到各行，进行格式修改：

207行：sprintf((char*)data,"0x%s",arg);

208行：len =compact_string((char *)data);

239行：next=(unsigned char*)arg;

241行：next=(unsigned char*)strchr((char *)next,',');

249行：next=(unsigned char*)arg;

252行：next=(unsigned char*)strchr(arg, ':');

262行：arg=(char *)next;

264行：next=(unsigned char*)strchr(arg, ',');

266行：next=(unsigned char*)arg-1; /* Finito - next points to */

270行：arg=(char *)next;

重新make通过

make install通过

安装完成

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tcpdump安装

yum install tcpdump -y

如果你那边不行,使用yum whatprovides tcpdump 查看哪个包支持tcpdump就安装哪个包

环境

close wait主要发送RST包，让close wait端释放

先说我这边的测试环境

close wait这端 是1.1.1.1  port 5000

client 端是 1.1.1.2 port 6000

在close wait这端执行 tcpdump -i eth0 port 5000 -vv   //eth0 是网卡选项，-vv 还是 -vvv 具体要看你那边的具体支持

如果也可以使用如下命令

tcpdump  -i eth4  host 1.1.1.1 and tcp port 5000   -vvv  监控本机上IP:Port 的包的收发  

下面分为2种情况：

1）tcpdump有输出结果

格式如下：

tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes

17:43:52.783330 IP (tos 0x0, ttl 64, id 49641, offset 0, flags [DF], proto TCP (6), length 52)

    1.1.1.1.commplex-main > 1.1.1.2.x11: Flags [.], cksum 0x9e3c (incorrect -> 0x32b3), seq 563052345, ack 2475188477, win 227, options [nop,nop,TS val 3719261472 ecr 3619406398], length 0

在client端执行

#sendip -v -p ipv4 -id 1.1.1.1 -is 1.1.1.2 -p tcp -td 5000 -ts 6000   -tfr 1 -tfs 0  -tn 2475188477     -tw 0  1.1.1.1

2) tcpdump 长时间没有输出结果

在client端执行

#sendip -v -p ipv4 -id 1.1.1.1 -is 1.1.1.2 -p tcp -td 5000 -ts 6000   -d 123  1.1.1.1