192.168.1.15是web伺服器，192.168.0.5是pc，從192.168.0.5通路192.168.1.15，通路192.168.1.15的80和22端口都比較慢，在192.168.1.15用指令tcpdump 'tcp[13] & 2 ==2' and \(dst or src 192.168.0.5\)抓取SYN 資料包，其結果如下：
通路80端口時：
server00:~# tcpdump 'tcp[13] & 2 ==2' and \(dst or src 192.168.0.5\)
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 96 bytes
16:39:36.243562 IP asian.14113 > 192.168.1.15.www: S 2091566485:2091566485(0) win 5840
16:39:39.242799 IP asian.14113 > 192.168.1.15.www: S 2091566485:2091566485(0) win 5840
16:39:43.437260 IP asian.13157 > 192.168.1.15.www: S 2504765917:2504765917(0) win 5840
16:39:43.438127 IP asian.12810 > 192.168.1.15.www: S 2506370553:2506370553(0) win 5840
16:39:45.240581 IP asian.14113 > 192.168.1.15.www: S 2091566485:2091566485(0) win 5840
16:39:46.434731 IP asian.13157 > 192.168.1.15.www: S 2504765917:2504765917(0) win 5840
16:39:46.435098 IP asian.12810 > 192.168.1.15.www: S 2506370553:2506370553(0) win 5840
16:39:57.237904 IP asian.14113 > 192.168.1.15.www: S 2091566485:2091566485(0) win 5840
16:40:18.637297 IP asian.13665 > 192.168.1.15.www: S 1399271655:1399271655(0) win 65535
16:40:18.637316 IP 192.168.1.15.www > asian.13665: S 3375036930:3375036930(0) ack 1399271656 win 5840
通路22端口時：
server00:~# tcpdump 'tcp[13] & 2 ==2' and \(dst or src 192.168.0.5\)
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 96 bytes
17:11:15.961614 IP asian.12813 > 192.168.1.15.22: S 4107113827:4107113827(0) win 5840
17:11:18.959110 IP asian.12813 > 192.168.1.15.22: S 4107113827:4107113827(0) win 5840
17:11:24.957810 IP asian.12813 > 192.168.1.15.22: S 4107113827:4107113827(0) win 5840
17:11:24.957836 IP 192.168.1.15.22 > asian.12813: S 1067633263:1067633263(0) ack 4107113828 win 5792
192.168.1.15在處理192.168.0.5的SYN請求時為什麼那麼慢？是以192.168.0.5經常出現連接配接逾時，但是一旦建立好了tcp連接配接，後面通路就很正常了，再過幾分鐘後又會連接配接逾時，是以是在建立tcp連接配接的時候存在問題，這不僅僅是處理http請求。連ssh的請求都慢，系統記憶體充足，負載還不到1，netstat -tn看到的才130個tcp連接配接，192.168.1.15是debian系統；這問題已經纏着我兩個星期了，請問各位遇到過類似問題嗎 ？