メールサーバーのアクセスロフト確認していると、約30分おきに、特定のIPアドレスからSMTPポートへの意味不明の接続が発生していることがわかりました。
ここ数日分の該当するmailog は以下の通り。
Oct 5 21:22:55 tokyo sm-mta[11950]: u95CMtMV011950: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 5 21:54:09 tokyo sm-mta[12050]: u95Cs9Wb012050: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 5 22:25:20 tokyo sm-mta[12972]: u95DPJAp012972: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 5 22:56:43 tokyo sm-mta[13073]: u95Duf2g013073: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 5 23:28:09 tokyo sm-mta[13212]: u95ES8NV013212: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 5 23:59:23 tokyo sm-mta[13316]: u95ExN2f013316: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 00:30:41 tokyo sm-mta[14227]: u95FUdNs014227: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 01:02:13 tokyo sm-mta[14324]: u95G2CTE014324: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 01:33:41 tokyo sm-mta[14397]: u95GXdXr014397: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 02:05:24 tokyo sm-mta[14474]: u95H5NJR014474: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 02:37:01 tokyo sm-mta[14555]: u95Hb1WF014555: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 03:08:45 tokyo sm-mta[14797]: u95I8hDC014797: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 03:40:30 tokyo sm-mta[17062]: u95IeT4F017062: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 04:12:04 tokyo sm-mta[17245]: u95JC3Fc017245: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 04:43:35 tokyo sm-mta[17294]: u95JhY3L017294: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 05:14:57 tokyo sm-mta[17399]: u95KEv9g017399: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 05:46:23 tokyo sm-mta[17489]: u95KkMjm017489: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 06:18:18 tokyo sm-mta[17589]: u95LIHJe017589: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 06:49:27 tokyo sm-mta[17658]: u95LnRMO017658: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 07:21:13 tokyo sm-mta[17755]: u95MLCHm017755: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 07:52:30 tokyo sm-mta[17837]: u95MqU2M017837: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 08:23:51 tokyo sm-mta[18800]: u95NNotw018800: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 08:55:17 tokyo sm-mta[18879]: u95NtHvQ018879: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 09:26:38 tokyo sm-mta[18983]: u960QcHI018983: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 09:58:00 tokyo sm-mta[19115]: u960vxNW019115: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 10:29:20 tokyo sm-mta[20189]: u961TJP1020189: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 11:00:23 tokyo sm-mta[20328]: u9620Nvj020328: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 11:31:37 tokyo sm-mta[20429]: u962VbrF020429: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 12:02:12 tokyo sm-mta[21447]: u9632CeM021447: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 12:33:22 tokyo sm-mta[21586]: u963XMdZ021586: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 13:04:36 tokyo sm-mta[21795]: u9644aDM021795: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 13:35:30 tokyo sm-mta[21910]: u964ZUZW021910: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 14:06:42 tokyo sm-mta[22865]: u9656gdN022865: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 14:38:02 tokyo sm-mta[22974]: u965c240022974: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 15:09:21 tokyo sm-mta[23098]: u9669LWg023098: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 15:40:33 tokyo sm-mta[23298]: u966eWsh023298: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 16:11:41 tokyo sm-mta[24307]: u967Bfba024307: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 16:42:50 tokyo sm-mta[24416]: u967gnSB024416: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 17:14:04 tokyo sm-mta[24563]: u968E4Kl024563: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 17:45:06 tokyo sm-mta[24686]: u968j6Au024686: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 18:16:18 tokyo sm-mta[25686]: u969GHbr025686: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 18:47:36 tokyo sm-mta[25774]: u969lanj025774: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 19:18:50 tokyo sm-mta[25934]: u96AIob6025934: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 19:50:03 tokyo sm-mta[26022]: u96Ao2B9026022: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 20:21:13 tokyo sm-mta[26956]: u96BLC31026956: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 20:52:21 tokyo sm-mta[27095]: u96BqLGv027095: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 21:23:35 tokyo sm-mta[27213]: u96CNZjs027213: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 21:55:14 tokyo sm-mta[27323]: u96CtEiP027323: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 22:26:20 tokyo sm-mta[28253]: u96DQKjg028253: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 22:56:52 tokyo sm-mta[28378]: u96DupT9028378: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 23:27:59 tokyo sm-mta[28494]: u96ERx45028494: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 6 23:59:02 tokyo sm-mta[28605]: u96Ex1I8028605: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 00:30:04 tokyo sm-mta[29621]: u96FU3vO029621: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 01:01:27 tokyo sm-mta[29714]: u96G1QIA029714: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 01:32:37 tokyo sm-mta[29788]: u96GWaSp029788: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 02:03:51 tokyo sm-mta[29886]: u96H3ov5029886: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 02:35:05 tokyo sm-mta[29960]: u96HZ4YM029960: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 03:06:31 tokyo sm-mta[30264]: u96I6Vv6030264: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 03:37:43 tokyo sm-mta[30511]: u96IbgFV030511: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 04:09:01 tokyo sm-mta[32994]: u96J919j032994: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 04:40:21 tokyo sm-mta[33064]: u96JeLXh033064: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 05:11:39 tokyo sm-mta[33308]: u96KBdvc033308: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 05:42:49 tokyo sm-mta[33362]: u96KgmYF033362: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 06:14:06 tokyo sm-mta[33466]: u96LE60C033466: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 06:45:17 tokyo sm-mta[33543]: u96LjGbF033543: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 07:16:38 tokyo sm-mta[33623]: u96MGb84033623: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 07:47:50 tokyo sm-mta[33679]: u96MloOA033679: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 08:20:08 tokyo sm-mta[34615]: u96NK84C034615: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 08:51:41 tokyo sm-mta[34711]: u96Npf5Y034711: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 09:22:07 tokyo sm-mta[34842]: u970M72v034842: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 09:53:37 tokyo sm-mta[34961]: u970rauK034961: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 10:24:58 tokyo sm-mta[35989]: u971Ovii035989: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 10:56:12 tokyo sm-mta[36092]: u971uBTb036092: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 11:27:32 tokyo sm-mta[36229]: u972RWOZ036229: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 11:58:55 tokyo sm-mta[36318]: u972wtvX036318: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 12:30:19 tokyo sm-mta[37292]: u973UIF5037292: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 13:01:44 tokyo sm-mta[37458]: u9741it3037458: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 13:33:08 tokyo sm-mta[37539]: u974X8O6037539: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 14:04:19 tokyo sm-mta[38510]: u9754IU3038510: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 14:35:09 tokyo sm-mta[38593]: u975Z8nx038593: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 15:05:13 tokyo sm-mta[38696]: u9765D6N038696: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 15:36:32 tokyo sm-mta[38791]: u976aWbq038791: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 16:06:40 tokyo sm-mta[39820]: u9776e98039820: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 16:37:53 tokyo sm-mta[39911]: u977brqj039911: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 17:09:14 tokyo sm-mta[40163]: u9789ENC040163: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 17:40:32 tokyo sm-mta[40253]: u978eW2w040253: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 18:11:36 tokyo sm-mta[41363]: u979Bamv041363: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 18:42:48 tokyo sm-mta[41435]: u979glpw041435: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 19:13:53 tokyo sm-mta[41562]: u97ADqkU041562: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 19:45:14 tokyo sm-mta[41670]: u97AjDh3041670: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 20:16:32 tokyo sm-mta[46509]: u97BGVZA046509: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 20:47:47 tokyo sm-mta[47150]: u97BlkU9047150: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 21:19:01 tokyo sm-mta[47246]: u97CJ1x3047246: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 21:50:31 tokyo sm-mta[47357]: u97CoVLw047357: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 22:21:31 tokyo sm-mta[48282]: u97DLVFu048282: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 22:52:49 tokyo sm-mta[48389]: u97DqnJS048389: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 23:24:05 tokyo sm-mta[48545]: u97EO5Wx048545: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 7 23:55:28 tokyo sm-mta[48648]: u97EtRd7048648: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 00:26:37 tokyo sm-mta[49620]: u97FQYDQ049620: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 00:57:58 tokyo sm-mta[49753]: u97Fvvfb049753: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 01:29:16 tokyo sm-mta[50028]: u97GTFgL050028: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 02:00:18 tokyo sm-mta[53395]: u97H0I96053395: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 02:31:34 tokyo sm-mta[53461]: u97HVYfJ053461: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 03:02:45 tokyo sm-mta[53645]: u97I2jsf053645: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 03:33:54 tokyo sm-mta[54013]: u97IXr2b054013: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 04:05:09 tokyo sm-mta[55813]: u97J59Kp055813: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 04:36:16 tokyo sm-mta[56003]: u97JaG3B056003: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 05:07:23 tokyo sm-mta[56086]: u97K7MNR056086: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 05:38:20 tokyo sm-mta[56150]: u97KcKLU056150: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 06:09:42 tokyo sm-mta[56252]: u97L9gxg056252: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 06:40:31 tokyo sm-mta[56331]: u97LeV54056331: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 07:11:52 tokyo sm-mta[56441]: u97MBpw4056441: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 07:43:03 tokyo sm-mta[56491]: u97Mh2OE056491: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 08:14:12 tokyo sm-mta[57446]: u97NEBdM057446: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 08:45:17 tokyo sm-mta[57545]: u97NjHNM057545: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 09:16:27 tokyo sm-mta[57649]: u980GRan057649: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 09:47:36 tokyo sm-mta[57729]: u980lZst057729: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 10:18:33 tokyo sm-mta[58620]: u981IXVT058620: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 10:49:35 tokyo sm-mta[58709]: u981nYMs058709: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 11:20:52 tokyo sm-mta[58849]: u982KqqJ058849: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 11:51:57 tokyo sm-mta[58982]: u982pvqR058982: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 12:23:07 tokyo sm-mta[59976]: u983N6ML059976: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 12:54:23 tokyo sm-mta[60053]: u983sMAv060053: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 13:25:24 tokyo sm-mta[60199]: u984POoa060199: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 13:56:33 tokyo sm-mta[60278]: u984uW99060278: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 14:27:42 tokyo sm-mta[61199]: u985Rf9J061199: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 14:58:53 tokyo sm-mta[61324]: u985wrv6061324: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 15:30:06 tokyo sm-mta[63118]: u986U5kt063118: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 16:01:20 tokyo sm-mta[65900]: u9871KXE065900: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 16:32:23 tokyo sm-mta[65980]: u987WMKG065980: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 17:03:32 tokyo sm-mta[66154]: u9883Wbg066154: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 17:34:45 tokyo sm-mta[66280]: u988YjhI066280: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 18:05:55 tokyo sm-mta[67235]: u9895s6d067235: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 18:37:07 tokyo sm-mta[67325]: u989b7vn067325: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 19:08:25 tokyo sm-mta[67430]: u98A8PQX067430: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 19:39:33 tokyo sm-mta[67545]: u98AdWTH067545: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 20:10:45 tokyo sm-mta[68447]: u98BAjfU068447: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 20:42:09 tokyo sm-mta[68587]: u98Bg9Xb068587: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 21:13:30 tokyo sm-mta[68800]: u98CDTTM068800: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 21:44:44 tokyo sm-mta[68929]: u98Ciiow068929: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 22:15:59 tokyo sm-mta[69847]: u98DFx0G069847: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 22:47:10 tokyo sm-mta[69975]: u98Dl9vc069975: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 23:18:28 tokyo sm-mta[70135]: u98EISrg070135: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 8 23:49:41 tokyo sm-mta[70224]: u98Enft8070224: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 00:20:58 tokyo sm-mta[71201]: u98FKwcd071201: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 00:52:09 tokyo sm-mta[71332]: u98Fq82C071332: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 01:23:04 tokyo sm-mta[71463]: u98GN30M071463: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 01:54:25 tokyo sm-mta[74873]: u98GsO57074873: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 02:25:39 tokyo sm-mta[74968]: u98HPdjk074968: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 02:56:53 tokyo sm-mta[75046]: u98HurGX075046: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 03:27:33 tokyo sm-mta[75532]: u98IRUlt075532: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 03:58:29 tokyo sm-mta[77231]: u98IwREA077231: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 04:29:46 tokyo sm-mta[77299]: u98JTjrH077299: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 05:01:09 tokyo sm-mta[77400]: u98K18al077400: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 05:32:28 tokyo sm-mta[77463]: u98KWRkM077463: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 06:03:33 tokyo sm-mta[77569]: u98L3WP0077569: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 06:34:44 tokyo sm-mta[77633]: u98LYgYJ077633: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 07:05:39 tokyo sm-mta[77728]: u98M5bEB077728: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 07:36:48 tokyo sm-mta[77814]: u98MalEW077814: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 08:07:50 tokyo sm-mta[78745]: u98N7mOC078745: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 08:38:59 tokyo sm-mta[78836]: u98NcwDo078836: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 09:10:12 tokyo sm-mta[78975]: u990ABOx078975: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 09:41:07 tokyo sm-mta[79063]: u990f7Tl079063: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 10:12:18 tokyo sm-mta[79974]: u991CI2i079974: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 10:43:16 tokyo sm-mta[80059]: u991hGqQ080059: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 11:14:21 tokyo sm-mta[80177]: u992ELmm080177: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 11:45:23 tokyo sm-mta[80280]: u992jMrt080280: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 12:16:25 tokyo sm-mta[81177]: u993GOrv081177: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 12:47:45 tokyo sm-mta[81291]: u993li54081291: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 13:19:06 tokyo sm-mta[81392]: u994J6Yn081392: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 13:50:10 tokyo sm-mta[81498]: u994o9kb081498: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 14:20:54 tokyo sm-mta[82517]: u995Ksa1082517: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 14:52:09 tokyo sm-mta[82624]: u995q9Jq082624: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 15:23:21 tokyo sm-mta[82750]: u996NLuB082750: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 15:54:26 tokyo sm-mta[82839]: u996sQY2082839: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 16:25:32 tokyo sm-mta[83741]: u997PWYP083741: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 16:56:44 tokyo sm-mta[83836]: u997ugT9083836: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 17:27:55 tokyo sm-mta[83991]: u998Rt7M083991: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 17:58:55 tokyo sm-mta[84071]: u998wsKX084071: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 18:30:09 tokyo sm-mta[85001]: u999U9kt085001: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 19:01:24 tokyo sm-mta[85126]: u99A1OlC085126: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 19:32:35 tokyo sm-mta[85255]: u99AWZ6X085255: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 20:03:37 tokyo sm-mta[86165]: u99B3bww086165: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 20:34:52 tokyo sm-mta[86274]: u99BYpvt086274: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 21:05:53 tokyo sm-mta[86402]: u99C5qFX086402: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 21:37:15 tokyo sm-mta[86501]: u99CbEP9086501: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 22:08:24 tokyo sm-mta[87437]: u99D8NUC087437: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 22:39:31 tokyo sm-mta[87561]: u99DdV08087561: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 23:10:49 tokyo sm-mta[87706]: u99EAmfv087706: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4 Oct 9 23:41:48 tokyo sm-mta[87836]: u99Efmk6087836: [52.175.17.187] did not issue MAIL/EXPN/VRFY/ETRN during connection to IPv4
「52.175.17.187」のアドレスはどこの国のもの？と whois で調べてみると・・・・・Microsoft が持っているIPアドレスでした。
NetRange: 52.145.0.0 - 52.191.255.255 CIDR: 52.146.0.0/15, 52.160.0.0/11, 52.145.0.0/16, 52.148.0.0/14, 52.152.0.0/13 NetName: MSFT NetHandle: NET-52-145-0-0-1 Parent: NET52 (NET-52-0-0-0-0) NetType: Direct Assignment OriginAS: Organization: Microsoft Corporation (MSFT) RegDate: 2015-11-24 Updated: 2015-11-24 Ref: https://whois.arin.net/rest/net/NET-52-145-0-0-1 OrgName: Microsoft Corporation OrgId: MSFT Address: One Microsoft Way City: Redmond StateProv: WA PostalCode: 98052 Country: US
そういえば、先日も Microsoft から Webサーバーへ奇妙なアクセスがあったことを思い出しました。
こんな事して一体何が目的？踏み台にするメールサーバーの所在をスキャンでもしているのだろうか？