I've been checking my /var/log/secure log recently and have seen the same bot trying to brute force onto my Centos server running webmin.

I created a chain + rule in Networking -> Linux Firewall:

Drop    If source is 113.106.88.146

But I'm still seeing the attempted logins in the log:

Jun  6 10:52:18 CentOS5 sshd[9711]: pam_unix(sshd:auth): check pass; user unknown
Jun  6 10:52:18 CentOS5 sshd[9711]: pam_succeed_if(sshd:auth): error retrieving information about user larry
Jun  6 10:52:19 CentOS5 sshd[9711]: Failed password for invalid user larry from 113.106.88.146 port 49328 ssh2

Here is the contents of /etc/sysconfig/iptables:

# Generated by webmin
*filter
:banned-ips - [0:0]
-A INPUT -p udp -m udp --dport ftp-data -j ACCEPT
-A INPUT -p udp -m udp --dport ftp -j ACCEPT
-A INPUT -p udp -m udp --dport domain -j ACCEPT
-A INPUT -p tcp -m tcp --dport 20000 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 10000 -j ACCEPT
-A INPUT -p tcp -m tcp --dport https -j ACCEPT
-A INPUT -p tcp -m tcp --dport http -j ACCEPT
-A INPUT -p tcp -m tcp --dport imaps -j ACCEPT
-A INPUT -p tcp -m tcp --dport imap -j ACCEPT
-A INPUT -p tcp -m tcp --dport pop3s -j ACCEPT
-A INPUT -p tcp -m tcp --dport pop3 -j ACCEPT
-A INPUT -p tcp -m tcp --dport ftp-data -j ACCEPT
-A INPUT -p tcp -m tcp --dport ftp -j ACCEPT
-A INPUT -p tcp -m tcp --dport domain -j ACCEPT
-A INPUT -p tcp -m tcp --dport smtp -j ACCEPT
-A INPUT -p tcp -m tcp --dport ssh -j ACCEPT
-A banned-ips -s 113.106.88.146 -j DROP
COMMIT
# Completed
# Generated by webmin
*mangle
:FORWARD ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
COMMIT
# Completed
# Generated by webmin
*nat
:OUTPUT ACCEPT [0:0]
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
COMMIT
# Completed