Como evitar probe de contas???

Pessoal,

como evitar isso no sendmail? Esses probes de contas de e-mail são um inferno. Existem alguma configuração ou pacote que monitora essas tentativas e bloqueia o IP da origem???

isso é só um pedaço do log. Imaginem que a palhaçada começou com
[email protected]


[]´s
Marcelo

Jul 15 09:19:13 voyager sendmail[1074]: h6F5aWY01074:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1125]: h6F5abY01125:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1108]: h6F5aZY01108:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1103]: h6F5aYY01103:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1198]: h6F5bJY01198:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1100]: h6F5aYY01100:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1102]: h6F5aYY01102:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1242]: h6F5buY01242:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1198]: h6F5bJY01198:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1242]: h6F5buY01242:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1074]: h6F5aWY01074:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1107]: h6F5aZY01107:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1104]: h6F5aYY01104:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1221]: h6F5bbY01221:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1107]: h6F5aZY01107:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1083]: h6F5aXY01083:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1082]: h6F5aXY01082:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1085]: h6F5aXY01085:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1053]: h6F5aVY01053:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1123]: h6F5abY01123:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1121]: h6F5aaY01121:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1157]: h6F5aoY01157:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1083]: h6F5aXY01083:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1170]: h6F5b2Y01170:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1236]: h6F5btY01236:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1123]: h6F5abY01123:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1157]: h6F5aoY01157:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1082]: h6F5aXY01082:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1123]: h6F5abY01123:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1236]: h6F5btY01236:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1170]: h6F5b2Y01170:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1121]: h6F5aaY01121:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1221]: h6F5bbY01221:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1074]: h6F5aWY01074:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1100]: h6F5aYY01100:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1103]: h6F5aYY01103:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1125]: h6F5abY01125:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1124]: h6F5aaY01124:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1126]: h6F5abY01126:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1080]: h6F5aXY01080:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1115]: h6F5aZY01115:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1158]: h6F5apY01158:
<[email protected]>... User unknown
Jul 15 09:19:13 voyager sendmail[1061]: h6F5aVY01061:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1058]: h6F5aVY01058:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1243]: h6F5buY01243:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1057]: h6F5aVY01057:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1101]: h6F5aYY01101:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1240]: h6F5btY01240:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1199]: h6F5bJY01199:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1200]: h6F5bJY01200:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1171]: h6F5b2Y01171:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1197]: h6F5bJY01197:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1055]: h6F5aVY01055:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1059]: h6F5aVY01059:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1171]: h6F5b2Y01171:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1199]: h6F5bJY01199:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1072]: h6F5aWY01072:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1127]: h6F5aaY01127:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1239]: h6F5btY01239:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1065]: h6F5aWY01065:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1116]: h6F5aZY01116:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1112]: h6F5aZY01112:
<[email protected]>... User unknown
Jul 15 09:19:14 voyager sendmail[1070]: h6F5aWY01070:
<[email protected]>... User unknown

[Pendosa]

Estou procurando alguma coisa sobre isso tb mas até agora nada.
Seria alguma ferramenta ou configuração no sendmail que, ao identificar muitos "user unknow" com mesma origem durante um intervalo de tempo automaticamente já o bloqueasse via IPTABLES/IPCHAINS ou /etc/mail/access

não há defesa contra isso????