1、查看內(nèi)存占用最大的進(jìn)程的命令:
ps aux| grep -v "USER" | sort -n -r -k 4 | awk 'NR==1{ print $0}'
2、查看所有建立連接的詳細(xì)記錄
netstat -nat|grep ESTABLISHED|wc -l
netstat -an | grep ESTABLISHED | wc -l
3、查看系統(tǒng)tcp連接中各個(gè)狀態(tài)的連接數(shù)/查看web的并發(fā)請(qǐng)求數(shù)及其TCP連接狀態(tài)
netstat -an | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'
4、輸出每個(gè)ip的連接數(shù),以及總的各個(gè)狀態(tài)的連接數(shù)。
netstat -n | awk '/^tcp/ {n=split($(NF-1),array,":");if(n<=2)++S[array[(1)]];else++S[array[(4)]];++s[$NF];++N} END {for(a in S){printf("%-20s %sn", a, S[a]);++I}printf("%-20s %sn","TOTAL_IP",I);for(a in s) printf("%-20s %sn",a, s[a]);printf("%-20s %sn","TOTAL_LINK",N);}'
5、TCP連接狀態(tài)詳解
LISTEN: 偵聽(tīng)來(lái)自遠(yuǎn)方的TCP端口的連接請(qǐng)求
SYN-SENT: 再發(fā)送連接請(qǐng)求后等待匹配的連接請(qǐng)求
SYN-RECEIVED:再收到和發(fā)送一個(gè)連接請(qǐng)求后等待對(duì)方對(duì)連接請(qǐng)求的確認(rèn)
ESTABLISHED:代表一個(gè)打開(kāi)的連接
FIN-WAIT-1: 等待遠(yuǎn)程TCP連接中斷請(qǐng)求,或先前的連接中斷請(qǐng)求的確認(rèn)
FIN-WAIT-2: 從遠(yuǎn)程TCP等待連接中斷請(qǐng)求
CLOSE-WAIT:等待從本地用戶(hù)發(fā)來(lái)的連接中斷請(qǐng)求
CLOSING: 等待遠(yuǎn)程TCP對(duì)連接中斷的確認(rèn)
LAST-ACK: 等待原來(lái)的發(fā)向遠(yuǎn)程TCP的連接中斷請(qǐng)求的確認(rèn)
TIME-WAIT: 等待足夠的時(shí)間以確保遠(yuǎn)程TCP接收到連接中斷請(qǐng)求的確認(rèn)
CLOSED: 沒(méi)有任何連接狀態(tài)