Bonjour,
Depuis quelques jours, il y a des attaques (?) de dovecot de ce type :
--------------------- pam_unix Begin ------------------------
dovecot:
Authentication Failures:
admin-help: 428 Time(s)
postmaster-relay: 399 Time(s)
som: 336 Time(s)
anonymous: 326 Time(s)
casa: 323 Time(s)
0: 318 Time(s)
sacha: 305 Time(s)
root: 36 Time(s)
abuse: 35 Time(s)
admin: 32 Time(s)
postmaster: 29 Time(s)
mailer-daemon: 28 Time(s)
alice: 3 Time(s)
broad: 3 Time(s)
comet2: 3 Time(s)
infoserv: 3 Time(s)
jb: 3 Time(s)
maxpayne: 3 Time(s)
mon2: 3 Time(s)
silent: 3 Time(s)
u2: 3 Time(s)
whatever43: 3 Time(s)
youth: 3 Time(s)
263: 2 Time(s)
3201: 2 Time(s)
AD: 2 Time(s)
Acrostichum: 2 Time(s)
Assets: 2 Time(s)
LoginForm: 2 Time(s)
Reflector: 2 Time(s)
abramov: 2 Time(s)
accepted: 2 Time(s)
ail: 2 Time(s)
antares: 2 Time(s)
anton1: 2 Time(s)
apriline: 2 Time(s)
area: 2 Time(s)
arny: 2 Time(s)
asd: 2 Time(s)
asdfg123: 2 Time(s)
baan: 2 Time(s)
bans: 2 Time(s)
basildonian: 2 Time(s)
basin: 2 Time(s)
behrmann: 2 Time(s)
benjamin: 2 Time(s)
bianca: 2 Time(s)
bilder: 2 Time(s)
bit: 2 Time(s)
blackbird-amsterdam: 2 Time(s)
bradfield: 2 Time(s)
brighton: 2 Time(s)
broken: 2 Time(s)
cai: 2 Time(s)
cecelia: 2 Time(s)
chaoping: 2 Time(s)
chris1: 2 Time(s)
chu-tin: 2 Time(s)
collab: 2 Time(s)
collect: 2 Time(s)
compaq: 2 Time(s)
console: 2 Time(s)
constanza: 2 Time(s)
corvair: 2 Time(s)
cpanel.demo: 2 Time(s)
ctf: 2 Time(s)
ctm: 2 Time(s)
current: 2 Time(s)
darklord: 2 Time(s)
dc2: 2 Time(s)
diah: 2 Time(s)
doit: 2 Time(s)
dori: 2 Time(s)
drweb: 2 Time(s)
dse: 2 Time(s)
dude: 2 Time(s)
duo: 2 Time(s)
econ: 2 Time(s)
elefante: 2 Time(s)
elektro: 2 Time(s)
elvis: 2 Time(s)
encounter: 2 Time(s)
eva: 2 Time(s)
fabian: 2 Time(s)
feng: 2 Time(s)
form: 2 Time(s)
forthcome: 2 Time(s)
gib: 2 Time(s)
gimli: 2 Time(s)
gloriam: 2 Time(s)
granite: 2 Time(s)
grt: 2 Time(s)
gus: 2 Time(s)
harada: 2 Time(s)
harish: 2 Time(s)
hc: 2 Time(s)
helga: 2 Time(s)
hoo: 2 Time(s)
iam: 2 Time(s)
informix: 2 Time(s)
install: 2 Time(s)
ipcam: 2 Time(s)
jimu: 2 Time(s)
jjh: 2 Time(s)
jsanchez: 2 Time(s)
kayako: 2 Time(s)
kibana: 2 Time(s)
kisskiss: 2 Time(s)
kolokol: 2 Time(s)
kops: 2 Time(s)
lavinia: 2 Time(s)
letters: 2 Time(s)
levi: 2 Time(s)
linksrv: 2 Time(s)
literacy: 2 Time(s)
luiza: 2 Time(s)
luping: 2 Time(s)
lyn: 2 Time(s)
lyncdiscover: 2 Time(s)
malcolm: 2 Time(s)
mariam: 2 Time(s)
marylou: 2 Time(s)
massage: 2 Time(s)
mc1: 2 Time(s)
mccarthy: 2 Time(s)
medved: 2 Time(s)
mirko: 2 Time(s)
monali: 2 Time(s)
mtm: 2 Time(s)
mtz: 2 Time(s)
mx25: 2 Time(s)
nadya: 2 Time(s)
nataly: 2 Time(s)
nec: 2 Time(s)
news2: 2 Time(s)
nine: 2 Time(s)
oaadmin: 2 Time(s)
offerte: 2 Time(s)
ogawa: 2 Time(s)
oh: 2 Time(s)
oj: 2 Time(s)
oki: 2 Time(s)
opennms: 2 Time(s)
p3: 2 Time(s)
pasta: 2 Time(s)
pav: 2 Time(s)
pearl1: 2 Time(s)
pegas: 2 Time(s)
pit: 2 Time(s)
pluton: 2 Time(s)
postmasters: 2 Time(s)
privacy: 2 Time(s)
ps3: 2 Time(s)
pz: 2 Time(s)
qazwsx123: 2 Time(s)
queen: 2 Time(s)
rdavila: 2 Time(s)
registro: 2 Time(s)
reinaldo: 2 Time(s)
remarks: 2 Time(s)
renamefile: 2 Time(s)
requestcompression: 2 Time(s)
richter: 2 Time(s)
s3cret: 2 Time(s)
sheri: 2 Time(s)
siteadmin: 2 Time(s)
skinny: 2 Time(s)
smtpmax: 2 Time(s)
sobranie: 2 Time(s)
society: 2 Time(s)
sp1: 2 Time(s)
srodriguez: 2 Time(s)
srvc22: 2 Time(s)
sweety2: 2 Time(s)
swf: 2 Time(s)
sztz: 2 Time(s)
teams: 2 Time(s)
test19: 2 Time(s)
test9: 2 Time(s)
tiffany: 2 Time(s)
timothy: 2 Time(s)
tome: 2 Time(s)
trigger: 2 Time(s)
tuyensinh: 2 Time(s)
ua2: 2 Time(s)
valentin: 2 Time(s)
vandal: 2 Time(s)
vianney: 2 Time(s)
volta: 2 Time(s)
webteam: 2 Time(s)
weidong: 2 Time(s)
wong: 2 Time(s)
wuge: 2 Time(s)
yusuf: 2 Time(s)
zbigniew: 2 Time(s)
zip: 2 Time(s)
000: 1 Time(s)
0000: 1 Time(s)
008: 1 Time(s)
1: 1 Time(s)
100: 1 Time(s)
1007238: 1 Time(s)
109: 1 Time(s)
111111111: 1 Time(s)
112061: 1 Time(s)
12121946: 1 Time(s)
123123: 1 Time(s)
123555: 1 Time(s)
123qwe: 1 Time(s)
14: 1 Time(s)
158: 1 Time(s)
186: 1 Time(s)
19721972: 1 Time(s)
1ab: 1 Time(s)
1qa2ws: 1 Time(s)
200: 1 Time(s)
2112: 1 Time(s)
219: 1 Time(s)
2232: 1 Time(s)
2252: 1 Time(s)
33: 1 Time(s)
350: 1 Time(s)
44444: 1 Time(s)
5065: 1 Time(s)
ALEX: 1 Time(s)
ATLAS: 1 Time(s)
Aaterfinns: 1 Time(s)
Adela: 1 Time(s)
Admin: 1 Time(s)
Administrators: 1 Time(s)
Ahepatokla: 1 Time(s)
Aileen: 1 Time(s)
Amelie: 1 Time(s)
Amphinesian: 1 Time(s)
Ana: 1 Time(s)
Apocynum: 1 Time(s)
Apoio: 1 Time(s)
AttachmentName: 1 Time(s)
AuthChildForm: 1 Time(s)
BACKUP: 1 Time(s)
BD: 1 Time(s)
Boff: 1 Time(s)
Bykkonen: 1 Time(s)
CHIEF: 1 Time(s)
Charles: 1 Time(s)
Collation: 1 Time(s)
Computer: 1 Time(s)
Dragon: 1 Time(s)
ER: 1 Time(s)
EXPORTTABLE: 1 Time(s)
Email: 1 Time(s)
Engineer1: 1 Time(s)
FaysaL: 1 Time(s)
Filename: 1 Time(s)
Georgebuck: 1 Time(s)
Graphics: 1 Time(s)
HOST: 1 Time(s)
Hallucinations: 1 Time(s)
INDEXCOLUMNLIST: 1 Time(s)
Jackson: 1 Time(s)
Jincheng: 1 Time(s)
KOY: 1 Time(s)
Katowice: 1 Time(s)
LLL: 1 Time(s)
Labor: 1 Time(s)
Lixin: 1 Time(s)
MCCAA: 1 Time(s)
MESLER: 1 Time(s)
Monitor: 1 Time(s)
ODS: 1 Time(s)
Olaussen: 1 Time(s)
Oncology: 1 Time(s)
Other: 1 Time(s)
P: 1 Time(s)
PDP: 1 Time(s)
Patches: 1 Time(s)
Peters: 1 Time(s)
Portal: 1 Time(s)
Postgres: 1 Time(s)
ROLLE: 1 Time(s)
RegisterForm: 1 Time(s)
Relay: 1 Time(s)
Richard: 1 Time(s)
Rimslut: 1 Time(s)
Rita: 1 Time(s)
SAMLResponse: 1 Time(s)
SANDBOX_README: 1 Time(s)
SERGEI: 1 Time(s)
SQLServer: 1 Time(s)
Save: 1 Time(s)
School: 1 Time(s)
Sender: 1 Time(s)
Senna: 1 Time(s)
Shooter: 1 Time(s)
SpamCheck: 1 Time(s)
Status: 1 Time(s)
Stephen: 1 Time(s)
Strickland: 1 Time(s)
SunShine: 1 Time(s)
Sunshine: 1 Time(s)
TEST5: 1 Time(s)
TTTT: 1 Time(s)
Thorstein: 1 Time(s)
VIVI: 1 Time(s)
VMAIL: 1 Time(s)
WEBADMIN: 1 Time(s)
Widget: 1 Time(s)
Yezi: 1 Time(s)
_savedok_x: 1 Time(s)
_savedokview_x: 1 Time(s)
aaaa: 1 Time(s)
aabbcc: 1 Time(s)
aarancibia: 1 Time(s)
aarp: 1 Time(s)
aavila: 1 Time(s)
abababab: 1 Time(s)
abas: 1 Time(s)
abc1234: 1 Time(s)
abc12345: 1 Time(s)
abcde: 1 Time(s)
abdulnasir: 1 Time(s)
aben: 1 Time(s)
abena1: 1 Time(s)
abhay: 1 Time(s)
abhishek: 1 Time(s)
abp: 1 Time(s)
abrt: 1 Time(s)
aca: 1 Time(s)
academics: 1 Time(s)
accelerator: 1 Time(s)
account_newsletters: 1 Time(s)
accountid: 1 Time(s)
accreditation: 1 Time(s)
acessoainformacao: 1 Time(s)
acp: 1 Time(s)
act: 1 Time(s)
activity: 1 Time(s)
ad3: 1 Time(s)
adad: 1 Time(s)
adams: 1 Time(s)
aday: 1 Time(s)
added: 1 Time(s)
addmeta: 1 Time(s)
address1: 1 Time(s)
ade: 1 Time(s)
adela: 1 Time(s)
adit: 1 Time(s)
aditya: 1 Time(s)
adm2: 1 Time(s)
admin_test: 1 Time(s)
admina: 1 Time(s)
admissions: 1 Time(s)
adriana: 1 Time(s)
adriel: 1 Time(s)
adrienne: 1 Time(s)
adscriptitius: 1 Time(s)
adwords: 1 Time(s)
adx: 1 Time(s)
affiliates: 1 Time(s)
afiliado: 1 Time(s)
afiliados: 1 Time(s)
aftermarket-robotech: 1 Time(s)
agatin: 1 Time(s)
agencia: 1 Time(s)
agglutinative: 1 Time(s)
agile: 1 Time(s)
agreement: 1 Time(s)
agri: 1 Time(s)
agronomia: 1 Time(s)
agung: 1 Time(s)
ahctv: 1 Time(s)
ahudson: 1 Time(s)
aide: 1 Time(s)
aileen: 1 Time(s)
aimee: 1 Time(s)
aimi: 1 Time(s)
aims: 1 Time(s)
ainsleigh: 1 Time(s)
aion: 1 Time(s)
ais: 1 Time(s)
aistest: 1 Time(s)
aito: 1 Time(s)
aitor: 1 Time(s)
ajohnson: 1 Time(s)
ajones: 1 Time(s)
ajxaction: 1 Time(s)
akane: 1 Time(s)
akashi: 1 Time(s)
ala: 1 Time(s)
alain2: 1 Time(s)
albany: 1 Time(s)
albertine: 1 Time(s)
aleksandr: 1 Time(s)
aleksey: 1 Time(s)
alexhot: 1 Time(s)
alexina: 1 Time(s)
alfa: 1 Time(s)
algarve: 1 Time(s)
algy: 1 Time(s)
alimentacion: 1 Time(s)
alive: 1 Time(s)
alk: 1 Time(s)
allan: 1 Time(s)
allianora: 1 Time(s)
allo: 1 Time(s)
allusers: 1 Time(s)
almoxarifado: 1 Time(s)
alnan: 1 Time(s)
aloha: 1 Time(s)
alumno: 1 Time(s)
amado: 1 Time(s)
amalia: 1 Time(s)
aman: 1 Time(s)
amano: 1 Time(s)
amar: 1 Time(s)
amms: 1 Time(s)
amp: 1 Time(s)
amp-scanner: 1 Time(s)
anamaria: 1 Time(s)
anand: 1 Time(s)
andante: 1 Time(s)
andie: 1 Time(s)
andina: 1 Time(s)
andre123: 1 Time(s)
andrew: 1 Time(s)
anet: 1 Time(s)
angela: 1 Time(s)
angelica: 1 Time(s)
anime: 1 Time(s)
ankang: 1 Time(s)
anna123: 1 Time(s)
annacc: 1 Time(s)
annaruth: 1 Time(s)
annualreport: 1 Time(s)
ant: 1 Time(s)
antaiva: 1 Time(s)
antanas: 1 Time(s)
anthony: 1 Time(s)
antony: 1 Time(s)
anu: 1 Time(s)
anucha: 1 Time(s)
anzen: 1 Time(s)
ap2: 1 Time(s)
ap3: 1 Time(s)
apa: 1 Time(s)
apc1: 1 Time(s)
apiv3-dev: 1 Time(s)
apm: 1 Time(s)
apofis: 1 Time(s)
apparel-de: 1 Time(s)
apple12: 1 Time(s)
appleid: 1 Time(s)
application: 1 Time(s)
appmail: 1 Time(s)
approved: 1 Time(s)
apptest: 1 Time(s)
april: 1 Time(s)
ara: 1 Time(s)
aragon: 1 Time(s)
arbeit: 1 Time(s)
arch: 1 Time(s)
archi: 1 Time(s)
archiv: 1 Time(s)
archiver: 1 Time(s)
arduino: 1 Time(s)
areaclienti: 1 Time(s)
argos: 1 Time(s)
arihant: 1 Time(s)
ark: 1 Time(s)
arkansas: 1 Time(s)
arnold: 1 Time(s)
arsenal: 1 Time(s)
art2: 1 Time(s)
articles: 1 Time(s)
artist: 1 Time(s)
artists: 1 Time(s)
asa: 1 Time(s)
asdf1234: 1 Time(s)
asgard: 1 Time(s)
asha: 1 Time(s)
ashley: 1 Time(s)
ashwin: 1 Time(s)
asia: 1 Time(s)
asp: 1 Time(s)
aspire: 1 Time(s)
asset: 1 Time(s)
assis: 1 Time(s)
association: 1 Time(s)
ast: 1 Time(s)
astrakhan: 1 Time(s)
astrix: 1 Time(s)
ata: 1 Time(s)
att: 1 Time(s)
attendance: 1 Time(s)
atusi: 1 Time(s)
auftrag: 1 Time(s)
august: 1 Time(s)
austin: 1 Time(s)
authkey: 1 Time(s)
authors: 1 Time(s)
authtype: 1 Time(s)
autodiscover.demo: 1 Time(s)
automail: 1 Time(s)
automation: 1 Time(s)
autossh: 1 Time(s)
autumn: 1 Time(s)
auxiliary: 1 Time(s)
ava: 1 Time(s)
avahi-autoipd: 1 Time(s)
avid: 1 Time(s)
avin: 1 Time(s)
avira: 1 Time(s)
avis: 1 Time(s)
awadhi: 1 Time(s)
awesome: 1 Time(s)
awhite: 1 Time(s)
aws-cache: 1 Time(s)
axelle: 1 Time(s)
azhar: 1 Time(s)
azurecom: 1 Time(s)
b10: 1 Time(s)
bac: 1 Time(s)
bacchus: 1 Time(s)
backends: 1 Time(s)
bahir: 1 Time(s)
baijialeyingqianfa: 1 Time(s)
balay: 1 Time(s)
balazs: 1 Time(s)
bamboo: 1 Time(s)
banger: 1 Time(s)
banners: 1 Time(s)
bannerweb: 1 Time(s)
bansubmit: 1 Time(s)
barcal: 1 Time(s)
barney: 1 Time(s)
barracuda: 1 Time(s)
barry: 1 Time(s)
bars: 1 Time(s)
bart: 1 Time(s)
...
zhaopin: 1 Time(s)
zhidao: 1 Time(s)
zhongshansijiazhentan: 1 Time(s)
zhoujing: 1 Time(s)
ziad: 1 Time(s)
zizzo: 1 Time(s)
zliu: 1 Time(s)
zmail: 1 Time(s)
zon1: 1 Time(s)
zuli: 1 Time(s)
zxcvb: 1 Time(s)
Invalid Users:
Unknown Account: 4723 Time(s)
Est-ce qu'il faut s'en soucier ?
Si oui, que faut-il mettre en oeuvre ?
D'avance merci.