Logwatch 메세지가 왔는데 분석이 어렵네요

주요부분만 간추리면..아래와 같습니다.

--------------------- pam_unix Begin ------------------------

crond:
Unknown Entries:
session closed for user root: 50 Time(s)
session opened for user root by (uid=0): 50 Time(s)

dovecot:
Unknown Entries:
authentication failure; logname= uid=0 euid=0 tty= ruser= rhost= user=jsh: 9 Time(s)
authentication failure; logname= uid=0 euid=0 tty= ruser= rhost= user=jyd6190: 5 Time(s)
bad username []: 1 Time(s)

sshd:
Authentication Failures:
unknown (218.188.2.174): 231 Time(s)
unknown (203.232.0.156): 6 Time(s)
root (203.232.0.156): 3 Time(s)
root (218.234.73.136): 2 Time(s)
root (218.188.2.174): 1 Time(s)
root (218.98.194.140): 1 Time(s)
unknown (201-0-10-126.dsl.telesp.net.br): 1 Time(s)
unknown (61.154.12.95): 1 Time(s)
Sessions Opened:
root by root: 6 Time(s)
Unknown Entries:
2 more authentication failures; logname= uid=0 euid=0 tty=ssh ruser= rhost=218.234.73.136 user=root: 1 Time(s)

---------------------- pam_unix End -------------------------

--------------------- sendmail Begin ------------------------

Bytes Transferred: 203235187
Messages Sent: 1734
Total recipients: 2208

14 messages returned after 2 hours

9 User Unknown notifications

1 Remote Protocol Errors's

2 Return Receipt's

WARNING!!!!
Possible Attack:
Attempt from 144.122.broadband2.iol.cz [83.208.122.144] with:
command=HELO/EHLO, count=3 : 1 Time(s)
Attempt from 161.62.broadband2.iol.cz [83.208.62.161] with:
command=HELO/EHLO, count=3 : 1 Time(s)
Attempt from 207-224-46-204.hlrn.qwest.net [207.224.46.204] with:
command=HELO/EHLO, count=3 : 1 Time(s)
Attempt from 69-29-247-158.dyn.centurytel.net [69.29.247.158] with:
command=HELO/EHLO, count=3 : 1 Time(s)
Attempt from 80.178.195.220.adsl.012.net.il [80.178.195.220] with:
command=HELO/EHLO, count=3 : 1 Time(s)
.
.
.
.
.
.
Unknown local users:

Total: 353

Top relays (recipients/connections - min 10 rcpts, max 50 lines):
391/125: [218.234.73.136]
105/96: [211.53.157.51]
56/8: [125.190.244.211]
56/8: [125.190.244.200]
53/49: [218.234.73.133]
47/47: [220.89.56.207]
36/36: [210.108.183.145]
30/30: [211.221.146.19]
27/27: [59.29.36.229]
22/22: [211.221.59.244]
18/16: [220.64.48.61]
16/15: [59.29.250.123]
16/16: [211.221.132.179]
13/13: [59.29.22.171]
12/5: [218.234.73.158]
10/10: [222.99.40.15]

Relaying denied:
From [121.131.112.116] to kim530@chollia.net: 1 Time(s)
From [121.131.112.116] to kim5716@jung.min.kk: 1 Time(s)
From [124.129.122.188] to ambition@yangsan.ac.kr: 1 Time(s)
From [124.129.122.188] to assistant@yangsan.ac.kr: 1 Time(s)
.
.
.
.
.
Total: 28

Client quit before communicating:
121.51.65.249 : 1 Time(s)
124.10.2.47 : 1 Time(s)
125-24-194-28.adsl.totbb.net : 1 Time(s)
125.130.197.183 : 1 Time(s)
125.22.132.40 : 1 Time(s)
125.22.91.162 : 1 Time(s)
.
.
.
.
.
쭈욱...백줄넘게 나오고

Authentication warnings:
[218.234.73.133] didn't use HELO protocol: 49 Time(s)

**Unmatched Entries**
kBCGfSRF002573[2]: avaliablesing.com]\n\t* 2.0 URIBL_OB_SURBL Contains an URL listed in the OB SURBL blocklist\n\t* [URIs: avaliablesing.com]: 1 Time(s)
[61.83.193.107]: possible SMTP attack: command=HELO/EHLO, count=3: 1 Time(s)
kBD9WGLZ013809[2]: tag\n\t* 0.0 FORGED_OUTLOOK_TAGS Outlook can't send HTML in this format\n\t* 0.0 MIME_HTML_ONLY_MULTI Multipart message only has text/html MIME parts\n\t* 0.0 RCVD_DOUBLE_IP_LOOSE Received: by and from look like IP addresses\n
.
.
.
이것도..엄청 많이..쭈욱 나옵니다.
그러다 마지막줄에

Summary:
Total Mail Rejected: 381

---------------------- sendmail End -------------------------

--------------------- SSHD Begin ------------------------

Failed logins from these:
root/password from ::ffff:218.98.194.140: 1 Time(s)

**Unmatched Entries**
Invalid user rfmngr from ::ffff:61.154.12.95 Failed password for invalid user rfmngr from ::ffff:61.154.12.95 port 51624 ssh2

---------------------- SSHD End -------------------------

좀 복잡해서..죄송합니다만..
주의를 요하거나 위험한 사항이 있으면
조언 부탁드립니다.