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