[읏힝]님이 남기신 글:

>-----------------------------------------
>답변자가 기본적으로 참고할 내용입니다.
>- 배포판(옵션)    : 
>- 커널버전(옵션)
  : 
>- 데몬버전(예:apache
 1.3.27) : 
>- 데몬설치유형(RPM/컴파일/기타)
 : 
>-----------------------------------------
>/var/log/messages입니다.

> 1 15:54:15 ns opensshd[22303]: Illegal user operator from
218.38.14.121
>May  1 15:54:15 ns opensshd[22303]: Failed password for illegal user operator from
218.38.14.121 port 52147 ssh2
>May  1 15:54:15 ns opensshd[22305]: Illegal user adm from 218.38.14.121
>May  1 15:54:15 ns opensshd[22305]: Failed password for illegal user adm from
218.38.14.121 port 52153 ssh2
>May  1 15:54:16 ns opensshd[22307]: Illegal user apache from
218.38.14.121
>May  1 15:54:16 ns opensshd[22307]: Failed password for illegal user apache from
218.38.14.121 port 52166 ssh2
>May  1 15:54:16 ns opensshd[22309]: Illegal user irc from 218.38.14.121
>May  1 15:54:16 ns opensshd[22309]: Failed password for illegal user irc from
218.38.14.121 port 52172 ssh2
>May  1 15:54:16 ns opensshd[22311]: Illegal user irc from 218.38.14.121
>May  1 15:54:16 ns opensshd[22311]: Failed password for illegal user irc from
218.38.14.121 port 52180 ssh2
>May  1 15:54:16 ns opensshd[22313]: Illegal user adm from 218.38.14.121
>May  1 15:54:16 ns opensshd[22313]: Failed password for illegal user adm from
218.38.14.121 port 52190 ssh2
>May  1 15:54:16 ns opensshd[22315]: Failed password for root from 218.38.14.121
port 52197 ssh2
>May  1 15:54:16 ns opensshd[22317]: Failed password for root from 218.38.14.121
port 52204 ssh2
>May  1 15:54:16 ns opensshd[22319]: Failed password for root from 218.38.14.121
port 52212 ssh2
>May  1 15:54:17 ns opensshd[22321]: Illegal user jane from
218.38.14.121
>May  1 15:54:17 ns opensshd[22321]: Failed password for illegal user jane from
218.38.14.121 port 52220 ssh2
>May  1 15:54:17 ns opensshd[22323]: Illegal user pamela from
218.38.14.121
>May  1 15:54:17 ns opensshd[22323]: Failed password for illegal user pamela from
218.38.14.121 port 52226 ssh2
>May  1 15:54:17 ns opensshd[22325]: Failed password for root from 218.38.14.121
port 52232 ssh2
>May  1 15:54:17 ns opensshd[22327]: Failed password for root from 218.38.14.121
port 52238 ssh2
>May  1 15:54:17 ns opensshd[22329]: Failed password for root from 218.38.14.121
port 52243 ssh2
>
>보시면 포트를 바꿔가면서
>SSH2 에 접속하려고 시도하는 듯 싶습니다.
>
>이사용자 접근 못하게 할 수 있는 방법이 없을까요? 

========================================

218.38.14.121 IP 주소에 대해서
리눅스라면 /etc/hosts.deny 에 설정하세요.
FreeBSD 는 /etc/hosts.allow 에 deny 설정하면 되고요.