转至：https://my.oschina.net/7shell/blog/70508
常用命令
查看所有80端口的连接数
1. netstat -nat|grep -i "80"|wc -l
对连接的IP按连接数量进行排序
1. netstat -ntu | awk ‘{print $5}‘ | cut -d: -f1 | sort | uniq -c | sort -n
查看TCP连接状态
1. netstat -nat |awk ‘{print $6}‘|sort|uniq -c|sort -rn
2. netstat -n | awk ‘/^tcp/ {++S[$NF]};END {for(a in S) print a, S[a]}‘
3. netstat -n | awk ‘/^tcp/ {++state[$NF]}; END {for(key in state) print key,"\t",state[key]}‘
4. netstat -n | awk ‘/^tcp/ {++arr[$NF]};END {for(k in arr) print k,"\t",arr[k]}‘
5. netstat -n |awk ‘/^tcp/ {print $NF}‘|sort|uniq -c|sort -rn
6. netstat -ant | awk ‘{print $NF}‘ | grep -v ‘[a-z]‘ | sort | uniq -c
查看80端口连接数最多的20个IP
1. netstat -anlp|grep 80|grep tcp|awk ‘{print $5}‘|awk -F: ‘{print $1}‘|sort|uniq -c|sort -nr|head -n20
2. netstat -ant |awk ‘/:80/{split($5,ip,":");++A[ip[1]]}END{for(i in A) print A,i}‘ |sort -rn|head -n20
用tcpdump嗅探80端口的访问看看谁最高
1. tcpdump -i eth0 -tnn dst port 80 -c 1000 | awk -F"." ‘{print $1"."$2"."$3"."$4}‘ | sort | uniq -c | sort -nr |head -20
查找较多time_wait连接
1. netstat -n|grep TIME_WAIT|awk ‘{print $5}‘|sort|uniq -c|sort -rn|head -n20
查找较多的SYN连接
1. netstat -an | grep SYN | awk ‘{print $5}‘ | awk -F: ‘{print $1}‘ | sort | uniq -c | sort -nr | more