请问这个日志是什么意思？

xmit***

Jan  1 10:03:06 sshd[28807]: Connection closed by 123.126.105.107 port 46342 [preauth]
Jan  1 10:03:08 sshd[28810]: Connection closed by 123.126.105.107 port 57094 [preauth]
Jan  1 10:03:13 sshd[28815]: Connection closed by 123.126.105.107 port 39640 [preauth]
Jan  1 10:03:17 sshd[28817]: Connection closed by 123.126.105.107 port 50412 [preauth]
Jan  1 10:03:21 sshd[28819]: Connection closed by 123.126.105.107 port 32946 [preauth]
Jan  1 10:03:24 sshd[28821]: Connection closed by 123.126.105.107 port 43714 [preauth]
Jan  1 10:03:28 sshd[28823]: Connection closed by 123.126.105.107 port 54486 [preauth]
Jan  1 10:03:37 sshd[28825]: Connection closed by 123.126.105.107 port 37058 [preauth]
Jan  1 10:03:40 sshd[28827]: Connection closed by 123.126.105.107 port 47816 [preauth]
Jan  1 10:03:45 sshd[28829]: Connection closed by 123.126.105.107 port 58592 [preauth]
Jan  1 10:03:48 sshd[28831]: Connection closed by 123.126.105.107 port 41128 [preauth]
Jan  1 10:03:52 sshd[28833]: Connection closed by 123.126.105.107 port 51900 [preauth]
Jan  1 10:03:56 sshd[28835]: Connection closed by 123.126.105.107 port 34444 [preauth]
Jan  1 10:04:00 sshd[28838]: Connection closed by 123.126.105.107 port 45206 [preauth]
Jan  1 10:04:04 sshd[28840]: Connection closed by 123.126.105.107 port 55976 [preauth]
Jan  1 10:04:08 sshd[28842]: Connection closed by 123.126.105.107 port 38512 [preauth]
Jan  1 10:04:18 sshd[28853]: Connection closed by 123.126.105.107 port 49326 [preauth]
Jan  1 10:04:19 sshd[28855]: Connection closed by 123.126.105.107 port 60072 [preauth]
Jan  1 10:04:24 sshd[28857]: Connection closed by 123.126.105.107 port 42618 [preauth]
Jan  1 10:04:28 sshd[28859]: Connection closed by 123.126.105.107 port 53392 [preauth]
Jan  1 10:04:31 sshd[28862]: Connection closed by 123.126.105.107 port 35926 [preauth]
Jan  1 10:04:36 sshd[28864]: Connection closed by 123.126.105.107 port 46698 [preauth]
Jan  1 10:04:39 sshd[28866]: Connection closed by 123.126.105.107 port 57458 [preauth]
Jan  1 10:04:43 sshd[28868]: Connection closed by 123.126.105.107 port 39996 [preauth]
Jan  1 10:04:47 sshd[28870]: Connection closed by 123.126.105.107 port 50772 [preauth]
Jan  1 10:04:56 sshd[28872]: Connection closed by 123.126.105.107 port 33344 [preauth]
Jan  1 10:04:57 sshd[28874]: Connection closed by 123.126.105.107 port 44092 [preauth]
Jan  1 10:05:02 sshd[28882]: Connection closed by 123.126.105.107 port 54870 [preauth]
Jan  1 10:05:06 sshd[28884]: Connection closed by 123.126.105.107 port 37410 [preauth]
Jan  1 10:05:11 sshd[28886]: Connection closed by 123.126.105.107 port 48186 [preauth]
Jan  1 10:05:14 sshd[28888]: Connection closed by 123.126.105.107 port 58942 [preauth]
Jan  1 10:05:18 sshd[28890]: Connection closed by 123.126.105.107 port 41480 [preauth]
Jan  1 10:05:22 sshd[28892]: Connection closed by 123.126.105.107 port 52258 [preauth]
Jan  1 10:05:26 sshd[28894]: Connection closed by 123.126.105.107 port 34794 [preauth]
Jan  1 10:05:34 sshd[28896]: Connection closed by 123.126.105.107 port 45436 [preauth]
Jan  1 10:05:38 sshd[28898]: Connection closed by 123.126.105.107 port 56354 [preauth]
Jan  1 10:05:41 sshd[28901]: Connection closed by 123.126.105.107 port 38884 [preauth]
Jan  1 10:05:45 sshd[28907]: Connection closed by 123.126.105.107 port 49654 [preauth]
Jan  1 10:05:49 sshd[28910]: Connection closed by 123.126.105.107 port 60418 [preauth]
Jan  1 10:05:53 sshd[28912]: Connection closed by 123.126.105.107 port 42956 [preauth]
Jan  1 10:05:57 sshd[28914]: Connection closed by 123.126.105.107 port 53722 [preauth]
Jan  1 10:06:01 sshd[28916]: Connection closed by 123.126.105.107 port 36266 [preauth]
Jan  1 10:06:05 sshd[28919]: Connection closed by 123.126.105.107 port 47036 [preauth]
Jan  1 10:06:14 sshd[28921]: Connection closed by 123.126.105.107 port 57910 [preauth]
Jan  1 10:06:18 sshd[28923]: Connection closed by 123.126.105.107 port 40372 [preauth]
Jan  1 10:06:21 sshd[28934]: Connection closed by 123.126.105.107 port 51138 [preauth]
Jan  1 10:06:25 sshd[28936]: Connection closed by 123.126.105.107 port 33674 [preauth]
Jan  1 10:06:29 sshd[28938]: Connection closed by 123.126.105.107 port 44442 [preauth]
Jan  1 10:06:33 sshd[28940]: Connection closed by 123.126.105.107 port 55206 [preauth]
Jan  1 10:06:37 sshd[28942]: Connection closed by 123.126.105.107 port 37750 [preauth]
Jan  1 10:06:41 sshd[28944]: Connection closed by 123.126.105.107 port 48516 [preauth]
Jan  1 10:06:45 sshd[28947]: Connection closed by 123.126.105.107 port 59282 [preauth]
Jan  1 10:06:53 sshd[28954]: Connection closed by 123.126.105.107 port 41852 [preauth]
Jan  1 10:06:57 sshd[28956]: Connection closed by 123.126.105.107 port 52628 [preauth]
Jan  1 10:07:00 sshd[28958]: Connection closed by 123.126.105.107 port 35154 [preauth]
Jan  1 10:07:04 sshd[28960]: Connection closed by 123.126.105.107 port 45928 [preauth]
Jan  1 10:07:08 sshd[28962]: Connection closed by 123.126.105.107 port 56690 [preauth]
Jan  1 10:07:12 sshd[28964]: Connection closed by 123.126.105.107 port 39234 [preauth]
Jan  1 10:07:16 sshd[28966]: Connection closed by 123.126.105.107 port 50000 [preauth]
Jan  1 10:07:20 sshd[28968]: Connection closed by 123.126.105.107 port 60774 [preauth]
Jan  1 10:07:24 sshd[28970]: Connection closed by 123.126.105.107 port 43312 [preauth]
Jan  1 10:07:31 sshd[28972]: Connection closed by 123.126.105.107 port 54108 [preauth]
Jan  1 10:07:36 sshd[28974]: Connection closed by 123.126.105.107 port 36650 [preauth]
Jan  1 10:07:39 sshd[28976]: Connection closed by 123.126.105.107 port 47412 [preauth]
Jan  1 10:07:43 sshd[28978]: Connection closed by 123.126.105.107 port 58184 [preauth]
Jan  1 10:07:47 sshd[28980]: Connection closed by 123.126.105.107 port 40720 [preauth]
Jan  1 10:07:51 sshd[28982]: Connection closed by 123.126.105.107 port 51504 [preauth]
Jan  1 10:07:55 sshd[28984]: Connection closed by 123.126.105.107 port 34036 [preauth]
Jan  1 10:07:59 sshd[28986]: Connection closed by 123.126.105.107 port 44806 [preauth]
Jan  1 10:08:06 sshd[28988]: Connection closed by 123.126.105.107 port 55598 [preauth]
Jan  1 10:08:10 sshd[28990]: Connection closed by 123.126.105.107 port 38142 [preauth]
Jan  1 10:08:15 sshd[28992]: Connection closed by 123.126.105.107 port 48916 [preauth]
Jan  1 10:08:18 sshd[28994]: Connection closed by 123.126.105.107 port 59668 [preauth]
Jan  1 10:08:22 sshd[28996]: Connection closed by 123.126.105.107 port 42212 [preauth]
Jan  1 10:08:26 sshd[28998]: Connection closed by 123.126.105.107 port 52986 [preauth]
Jan  1 10:08:30 sshd[29000]: Connection closed by 123.126.105.107 port 35528 [preauth]
Jan  1 10:08:34 sshd[29002]: Connection closed by 123.126.105.107 port 46288 [preauth]
Jan  1 10:08:38 sshd[29004]: Connection closed by 123.126.105.107 port 57060 [preauth]
Jan  1 10:08:47 sshd[29006]: Connection closed by 123.126.105.107 port 39634 [preauth]
Jan  1 10:08:49 sshd[29008]: Connection closed by 123.126.105.107 port 50376 [preauth]
Jan  1 10:08:54 sshd[29010]: Connection closed by 123.126.105.107 port 32932 [preauth]
Jan  1 10:08:58 sshd[29012]: Connection closed by 123.126.105.107 port 43702 [preauth]
Jan  1 10:09:02 sshd[29014]: Connection closed by 123.126.105.107 port 54470 [preauth]
Jan  1 10:09:06 sshd[29016]: Connection closed by 123.126.105.107 port 37016 [preauth]
Jan  1 10:09:10 sshd[29018]: Connection closed by 123.126.105.107 port 47792 [preauth]
Jan  1 10:09:14 sshd[29020]: Connection closed by 123.126.105.107 port 58552 [preauth]
Jan  1 10:09:18 sshd[29022]: Connection closed by 123.126.105.107 port 41098 [preauth]
Jan  1 10:09:27 sshd[29024]: Connection closed by 123.126.105.107 port 51908 [preauth]
Jan  1 10:09:28 sshd[29026]: Connection closed by 123.126.105.107 port 34414 [preauth]
Jan  1 10:09:33 sshd[29028]: Connection closed by 123.126.105.107 port 45188 [preauth]
Jan  1 10:09:38 sshd[29030]: Connection closed by 123.126.105.107 port 55962 [preauth]
Jan  1 10:09:41 sshd[29032]: Connection closed by 123.126.105.107 port 38496 [preauth]
Jan  1 10:09:45 sshd[29034]: Connection closed by 123.126.105.107 port 49274 [preauth]
Jan  1 10:09:49 sshd[29036]: Connection closed by 123.126.105.107 port 60046 [preauth]
Jan  1 10:09:53 sshd[29040]: Connection closed by 123.126.105.107 port 42580 [preauth]
Jan  1 10:09:57 sshd[29042]: Connection closed by 123.126.105.107 port 53356 [preauth]
Jan  1 10:10:06 sshd[29050]: Connection closed by 123.126.105.107 port 35940 [preauth]
Jan  1 10:10:06 sshd[29052]: Connection closed by 123.126.105.107 port 46664 [preauth]
Jan  1 10:10:12 sshd[29055]: Connection closed by 123.126.105.107 port 57454 [preauth]
Jan  1 10:10:16 sshd[29057]: Connection closed by 123.126.105.107 port 39994 [preauth]
Jan  1 10:10:21 sshd[29059]: Connection closed by 123.126.105.107 port 50762 [preauth]
Jan  1 10:10:24 sshd[29061]: Connection closed by 123.126.105.107 port 33294 [preauth]
Jan  1 10:10:28 sshd[29063]: Connection closed by 123.126.105.107 port 44060 [preauth]
Jan  1 10:10:32 sshd[29065]: Connection closed by 123.126.105.107 port 54842 [preauth]
Jan  1 10:10:36 sshd[29067]: Connection closed by 123.126.105.107 port 37384 [preauth]
Jan  1 10:10:44 sshd[29069]: Connection closed by 123.126.105.107 port 48178 [preauth]
Jan  1 10:10:46 sshd[29071]: Connection closed by 123.126.105.107 port 58930 [preauth]