外出から戻ってみると、サーバーのログ画面がいつもと何か違う。
高負荷状態が何十分か続いていた形跡が残っていました。サーバーが高負荷になるのは HTTPD が酷使された場合なので Apache のログを見てみると、次のようなアクセスログが大量に残っていました。
network176-254.wctc.net - - [03/Apr/2018:18:35:53 +0900] "GET /notes/2013/06/14/freebsd-7-3-upgraded-to-8-3-from-network/ HTTP/1.1" 200 82317 "https://statecarinsurance.us" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)" bb4221ed.virtua.com.br - - [03/Apr/2018:18:36:09 +0900] "GET /notes/2013/06/14/freebsd-7-3-upgraded-to-8-3-from-network/ HTTP/1.1" 200 19253 "https://statecarinsurance.us" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)" network176-254.wctc.net - - [03/Apr/2018:18:35:53 +0900] "GET /notes/2013/06/14/freebsd-7-3-upgraded-to-8-3-from-network/ HTTP/1.1" 200 79983 "https://statecarinsurance.us" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)" 75-165-110-75.crls.qwest.net - - [03/Apr/2018:18:37:17 +0900] "GET /notes/2013/06/14/freebsd-7-3-upgraded-to-8-3-from-network/ HTTP/1.1" 200 19253 "https://statecarinsurance.us" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)" egress422.cws.sco.cisco.com - - [03/Apr/2018:18:36:37 +0900] "GET /notes/2013/06/14/freebsd-7-3-upgraded-to-8-3-from-network/ HTTP/1.1" 200 82317 "https://statecarinsurance.us" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT5.1; SV1)"
このあとサーバーが高負荷になり、/var/log/messages に次の行が残っていました。
Apr 3 18:38:30 server kernel: sonewconn: pcb 0xcda8abd0: Listen queue overflow: 193 already in queue awaiting acceptance (1 occurrences) Apr 3 18:39:32 server kernel: sonewconn: pcb 0xcda8abd0: Listen queue overflow: 193 already in queue awaiting acceptance (251 occurrences) Apr 3 18:40:32 server kernel: sonewconn: pcb 0xcda8abd0: Listen queue overflow: 193 already in queue awaiting acceptance (195 occurrences) Apr 3 18:41:33 server kernel: sonewconn: pcb 0xcda8abd0: Listen queue overflow: 193 already in queue awaiting acceptance (210 occurrences) Apr 3 18:42:40 server kernel: sonewconn: pcb 0xcda8abd0: Listen queue overflow: 193 already in queue awaiting acceptance (166 occurrences) Apr 3 18:45:13 server kernel: sonewconn: pcb 0xcda8abd0: Listen queue overflow: 193 already in queue awaiting acceptance (17 occurrences) Apr 3 18:46:14 server kernel: sonewconn: pcb 0xcda8abd0: Listen queue overflow: 195 already in queue awaiting acceptance (101 occurrences) Apr 3 18:50:10 server kernel: sonewconn: pcb 0xcda8abd0: Listen queue overflow: 193 already in queue awaiting acceptance (84 occurrences)
Apache のログじゃなくてカーネルのログとして残っているのが気持ち悪いところ。
何が目的？