I have Centos 5.7 64bit; I have installed vsftpd as standalone service and using it for two years now with no problem. Suddenly; only it works with active mode. The passive mode stops working and gives time out. Firewall is disabled and SELinux is set to permissive. I ran tcpdump and I noticed that only first three packets reached the FTP for passive mode and no more packets on other ports # lsmod | grep conntrack ip_conntrack_ftp 41361 1 ip_nat_ftp ip_conntrack_netbios_ns 36033 0 ip_conntrack 91621 5 ip_nat_ftp,ip_nat,ip_conntrack_ftp,ip_conntrack_netbios_ns,xt_state nfnetlink 40457 2 ip_nat,ip_conntrack Any suggestion? Eng. Fawzy Ibrahim Linux Systems Administrator