comet模型的主机维持长连接，单台连接接数可以达到百万（现网目前用的最高单台可达到60万左右），在统计网络连接状态时会netstat会长期不响应，而SS命令统计相对较快，不过输出不够美观 。本篇主要总结下comet模型下的连接数常见统计方法。tcp连接主机是通过读取/proc/net/tcp文件进行的统计。具体每项值的意思见下图（点击可查看大图）
一、C++ 代码实现连接数统计
[root@361way netstat]# cat ss++.cc
// code from www.361way.com
#include<iostream>
#include<fstream>
#include<cstdlib>
#include<sstream>
using namespace std;
//struct: Property of a tcp connection
struct ConnectionProperty
{
string local_addr;
string remote_addr;
string state;
};
//Change hexadecimal number to decimal number
int HexToInt(char h)
{
if(h >= '0' && h <= '9')
{
return h - '0';
}
else if(h >= 'A' && h <= 'F')
{
return h - 'A' + 10;
}
else
{
cerr << "Error: Illegal Hex Number!" << endl;
return -1;
}
}
//Get Ip address and port number from string XXXXXXXX:XXXX
string GetIpAddress(char* str)
{
int a, b, c, d, e;
a = HexToInt(str[0]) * 16 + HexToInt(str[1]);
b = HexToInt(str[2]) * 16 + HexToInt(str[3]);
c = HexToInt(str[4]) * 16 + HexToInt(str[5]);
d = HexToInt(str[6]) * 16 + HexToInt(str[7]);
e = HexToInt(str[9]) * 16 * 16 * 16 +
HexToInt(str[10]) * 16 * 16 +
HexToInt(str[11]) * 16 +
HexToInt(str[12]);
//change int to string
string sa, sb, sc, sd, se;
ostringstream oss;
oss << a;
sa = oss.str();
oss.str(""); //clear the content in oss
oss << b;
sb = oss.str();
oss.str("");
oss << c;
sc = oss.str();
oss.str("");
oss << d;
sd = oss.str();
oss.str("");
oss << e;
se = oss.str();
oss.str("");
//return by order: d.c.b.a:e
return sd + '.' + sc + '.' + sb + '.' + sa + ':' + se;
}
//Get tcp connection state
string GetConnectionState(char* str)
{
if(str[0] == '0' && str[1] == '0') return "ERROR_STATUS";
if(str[0] == '0' && str[1] == '1') return "TCP_ESTABLISHED";
if(str[0] == '0' && str[1] == '2') return "TCP_SYN_SENT";
if(str[0] == '0' && str[1] == '3') return "TCP_SYN_RECV";
if(str[0] == '0' && str[1] == '4') return "TCP_FIN_WAIT1";
if(str[0] == '0' && str[1] == '5') return "TCP_FIN_WAIT2";
if(str[0] == '0' && str[1] == '6') return "TCP_TIME_WAIT";
if(str[0] == '0' && str[1] == '7') return "TCP_CLOSE";
if(str[0] == '0' && str[1] == '8') return "TCP_CLOSE_WAIT";
if(str[0] == '0' && str[1] == '9') return "TCP_LAST_ACK";
if(str[0] == '0' && str[1] == 'A') return "TCP_LISTEN";
if(str[0] == '0' && str[1] == 'B') return "TCP_CLOSING";
return "UNKNOWN_STATE";
}
int main()
{
//read from file /proc/net/tcp
ifstream infile("/proc/net/tcp", ios :: in);
if(!infile)
{
cerr << "open error!" << endl;
exit(1);
}
string s;
char s_local_addr[20], s_remote_addr[20], s_state[20];
getline(infile, s); //title: every column's name
while(getline(infile, s))
{
sscanf(s.c_str(), "%*s%s%s%s", s_local_addr, s_remote_addr, s_state);
//printf("%s\t%s\t%s\n", s_local_addr, s_remote_addr, s_state);
string ip_local = GetIpAddress(s_local_addr);
string ip_remote = GetIpAddress(s_remote_addr);
string conn_state = GetConnectionState(s_state);
cout << ip_local << "\t" << ip_remote << "\t" << conn_state << endl;
}
return 0;
}
通过如下代码编译生成可执行文件： g++ -o netinfo ss++.cc，执行输出如下：
[root@comethost ~]# ./netinfo
115.28.174.118:5224 121.31.251.8:13351 TCP_ESTABLISHED
115.28.174.118:5229 223.104.23.84:62815 TCP_ESTABLISHED
115.28.174.118:5225 117.136.79.70:45116 TCP_ESTABLISHED
115.28.174.118:5224 112.17.243.208:33236 TCP_ESTABLISHED
115.28.174.118:5224 27.204.14.135:44976 TCP_ESTABLISHED
115.28.174.118:5228 58.18.233.29:60135 TCP_ESTABLISHED
115.28.174.118:5226 112.17.246.84:26055 TCP_ESTABLISHED
二、python实现tcp连接统计
#!/usr/bin/env python
# code from www.361way.com
# coding=utf-8
import pwd
import os
import re
import glob
PROC_TCP = "/proc/net/tcp"
STATE = {
'01':'ESTABLISHED',
'02':'SYN_SENT',
'03':'SYN_RECV',
'04':'FIN_WAIT1',
'05':'FIN_WAIT2',
'06':'TIME_WAIT',
'07':'CLOSE',
'08':'CLOSE_WAIT',
'09':'LAST_ACK',
'0A':'LISTEN',
'0B':'CLOSING'
}
def _load():
''' Read the table of tcp connections & remove header '''
with open(PROC_TCP,'r') as f:
content = f.readlines()
content.pop(0)
return content
def _hex2dec(s):
return str(int(s,16))
def _ip(s):
ip = [(_hex2dec(s[6:8])),(_hex2dec(s[4:6])),(_hex2dec(s[2:4])),(_hex2dec(s[0:2]))]
return '.'.join(ip)
def _remove_empty(array):
return [x for x in array if x !='']
def _convert_ip_port(array):
host,port = array.split(':')
return _ip(host),_hex2dec(port)
def netstat():
'''
Function to return a list with status of tcp connections at linux systems
To get pid of all network process running on system, you must run this script
as superuser
'''
content=_load()
result = []
for line in content:
line_array = _remove_empty(line.split(' ')) # Split lines and remove empty spaces.
l_host,l_port = _convert_ip_port(line_array[1]) # Convert ipaddress and port from hex to decimal.
r_host,r_port = _convert_ip_port(line_array[2])
state = STATE[line_array[3]]
nline = [ l_host+':'+l_port, r_host+':'+r_port, state ]
result.append(nline)
return result
if __name__ == '__main__':
for conn in netstat():
print conn
三、ss统计
默认安装完iproute2包后，里面包含有ss工具，不过想要查看ss的源码可以到https://github.com/shemminger/iproute2/blob/master/misc/ss.c 查看 。
四、统计速率统计
这里只找了一台连接数在20多万的comet服务器进行的测试，从执行效果来看：
- ss -nt执行速度最快
-
c++版的netinfo与ss接近（稍慢于c语言版的ss）
-
python版的比ss与netinfo慢五到六倍
-
netstat没做测试，根据之前的了解，估计与python版的接近或者差于python版的
所以后续现网有简单的连接数统计需求，会优先选择c++版的ss（输出美观），而且可以在此基础上简单定制 。
参考页面：
python版的ss参考 voorloopnul
相关代码已上传至我的github ：https://github.com/361way/python/tree/master/netstat