在線關閉 CLOSE_WAIT狀態TCP連接

1、查看某個端口的所有TCP連接：

[root@Centos projects]# netstat -anp | grep 8087
tcp6       0      0 :::8087                 :::*                    LISTEN      4931/java           
tcp6       1      0 192.168.229.140:8087    192.168.229.1:10664     CLOSE_WAIT  4931/java           
tcp6       1      0 192.168.229.140:8087    192.168.229.1:10665     CLOSE_WAIT  4931/java           
tcp6       1      0 192.168.229.140:8087    192.168.229.1:10671     CLOSE_WAIT  4931/java           
tcp6       1      0 192.168.229.140:8087    192.168.229.1:10668     CLOSE_WAIT  4931/java           
tcp6       1      0 192.168.229.140:8087    192.168.229.1:10670     CLOSE_WAIT  4931/java           
[root@Centos projects]# 

2、獲取 CLOSE_WAIT 狀態連接的文件描述符：

[root@Centos projects]# lsof -np 4931 | grep "CLOSE_WAIT"
java    4931 root   27u     IPv6              75515       0t0      TCP 192.168.229.140:simplifymedia->192.168.229.1:10764 (CLOSE_WAIT)
java    4931 root   28u     IPv6              75516       0t0      TCP 192.168.229.140:simplifymedia->192.168.229.1:10765 (CLOSE_WAIT)
java    4931 root   30u     IPv6              75517       0t0      TCP 192.168.229.140:simplifymedia->192.168.229.1:10768 (CLOSE_WAIT)
java    4931 root   31u     IPv6              75518       0t0      TCP 192.168.229.140:simplifymedia->192.168.229.1:10769 (CLOSE_WAIT)
java    4931 root   33u     IPv6              75183       0t0      TCP 192.168.229.140:simplifymedia->192.168.229.1:10763 (CLOSE_WAIT)
[root@Centos projects]# lsof -np 4931 | grep "CLOSE_WAIT" | awk '{print $4}'
27u
28u
30u
31u
33u
[root@Centos projects]# 

3、使用GDB關閉 CLOSE_WAIT狀態連接：

[root@Centos projects]# gdb -p 4931　　# 連接到 4931 進程
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-94.el7
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Attaching to process 4931
...（略去內容）...
(gdb) 　　　　　　　　　　# 這里為 gdb 命令提示符

然后根據文件描述符關閉指定的 socket 連接：

(gdb) call close(27u)　　# 27u即 close_wait 狀態連接的文件描述符
...(略去內容)...