syn flood?

[Marek Hevier]

Zdravim znovu celu konferu....
mam tu problem, s ktorym neviem zatial pohnut...
Na server jednoducho neprichadza posta, a odchodziu server posle, iba z 
jednej domeny ju vracia.
Mam RH71 a pouzivam sendmail.
vypis logov pre onu spominanu domenu:

Nov  5 20:27:25 uhra sendmail[22497]: hA4MiIa15795: to=<vjanco na post.sk>, 
ctladdr=<vladus na uhra.mtf.stuba.sk> (518/45), delay=20:43:07, 
xdelay=00:00:01, mailer=esmtp, pri=103531122, relay=smtp.post.sk. 
[217.67.20.134], dsn=4.0.0, stat=Deferred: Connection refused by 
smtp.post.sk.

Mam podozrenie ze to moze suvisiet nejak s DOS utokom, pretoze po 
netstatnuti dostanem nasledovny vysledok:

tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:25              0.0.0.0:*               LISTEN
tcp        0      0 147.175.139.10:25       12.129.205.51:11557     SYN_RECV
tcp        0      0 147.175.139.10:25       62.168.28.239:4859      SYN_RECV
tcp        0      0 147.175.139.10:25       12.129.205.60:19703     SYN_RECV
tcp        0      0 147.175.139.10:25       62.168.28.239:4860      SYN_RECV
tcp        0      0 147.175.139.10:25       64.156.187.151:51089    SYN_RECV
tcp        0      0 147.175.139.10:25       12.129.205.67:25883     SYN_RECV
tcp        0      0 147.175.139.10:25       12.129.205.45:38839     SYN_RECV
tcp        0      0 147.175.139.10:25       12.129.205.69:49654     SYN_RECV
tcp        0      0 147.175.139.10:25       12.129.205.58:8259      SYN_RECV
tcp        0      0 147.175.139.10:25       212.5.216.21:46416      SYN_RECV

zapis v /etc/hosts.allow

sendmail: all EXCEPT PARANOID

vie mi niekto pomoct? vopred dakujem
Marek