Attaque wu-ftpd ?

Bonjour,
J’ai le log suivant dans le fichier /var/log/messages.

Vous pensez que s’est une tentative de piratage?

Il y a un moyen de contrer efficacement?

Merci d’avance

Nov 11 17:25:23 thor wu-ftpd[27636]: failed login from 61.152.239.49 [61.152.239.49]                                                                                   
Nov 11 17:25:41 thor last message repeated 4 times                                                                                                                     
Nov 11 17:25:41 thor wu-ftpd[27636]: repeated login failures from 61.152.239.49 [61.152.239.49]                                                                        
Nov 11 17:26:05 thor wu-ftpd[27639]: failed login from 61.152.239.49 [61.152.239.49]                                                                                   
Nov 11 17:26:23 thor last message repeated 4 times                                                                                                                     
Nov 11 17:26:23 thor wu-ftpd[27639]: repeated login failures from 61.152.239.49 [61.152.239.49]                                                                        
Nov 11 17:26:47 thor wu-ftpd[27640]: failed login from 61.152.239.49 [61.152.239.49]                                                                                   
Nov 11 17:27:06 thor last message repeated 4 times                                                                                                                     
Nov 11 17:27:06 thor wu-ftpd[27640]: repeated login failures from 61.152.239.49 [61.152.239.49]                                                                        
Nov 11 17:27:30 thor wu-ftpd[27641]: failed login from 61.152.239.49 [61.152.239.49]                                                                                   
Nov 11 17:27:48 thor last message repeated 4 times                                                                                                                     
Nov 11 17:27:48 thor wu-ftpd[27641]: repeated login failures from 61.152.239.49 [61.152.239.49]                                                                        
Nov 11 17:28:12 thor wu-ftpd[27642]: failed login from 61.152.239.49 [61.152.239.49]                                                                                   
Nov 11 17:28:31 thor last message repeated 4 times                                                                                                                     
Nov 11 17:28:31 thor wu-ftpd[27642]: repeated login failures from 61.152.239.49 [61.152.239.49]                                                                        
Nov 11 17:28:53 thor wu-ftpd[27643]: failed login from 61.152.239.49 [61.152.239.49]                                                                                   
Nov 11 17:29:11 thor last message repeated 4 times                                                                                                                     
Nov 11 17:29:11 thor wu-ftpd[27643]: repeated login failures from 61.152.239.49 [61.152.239.49]                                                                        
Nov 11 17:29:34 thor wu-ftpd[27644]: failed login from 61.152.239.49 [61.152.239.49]                                                                                   
Nov 11 17:29:52 thor last message repeated 4 times 

x@eol:~$ whois 61.152.239.49
% [whois.apnic.net node-1]
% Whois data copyright terms apnic.net/db/dbcopyright.html

inetnum: 61.152.0.0 - 61.152.255.255
netname: CHINANET-SH
descr: CHINANET Shanghai province network
descr: Data Communication Division
descr: China Telecom
country: CN
admin-c: CH93-AP
tech-c: XI5-AP
mnt-by: APNIC-HM
mnt-lower: MAINT-CHINANET-SH
mnt-routes: MAINT-CHINANET-SH
status: ALLOCATED PORTABLE
changed: hm-changed@apnic.net 20060427
source: APNIC

person: Chinanet Hostmaster
nic-hdl: CH93-AP
e-mail: anti-spam@ns.chinanet.cn.net
address: No.31 ,jingrong street,beijing
address: 100032
phone: +86-10-58501724
fax-no: +86-10-58501724
country: CN
changed: dingsy@cndata.com 20070416
mnt-by: MAINT-CHINANET
source: APNIC

person: Wu Xiao Li
address: Room 805,61 North Si Chuan Road,Shanghai,200085,PRC
country: CN
phone: +86-21-63630562
fax-no: +86-21-63630566
e-mail: ip-admin@mail.online.sh.cn
nic-hdl: XI5-AP
mnt-by: MAINT-CHINANET-SH
changed: ip-admin@mail.online.sh.cn 20010510
source: APNIC