>Number:         29531
>Category:       kern
>Synopsis:       Active FTP support with NAT causes panic
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Feb 26 05:15:00 +0000 2005
>Originator:     Ari Sovijärvi
>Release:        NetBSD 2.0
>Organization:
Private	
>Environment:
System: NetBSD server2 2.0 NetBSD 2.0 (TAME-III) #0: Sun Feb 13 08:31:27 EET 2005 root@server2:/usr/obj/sys/arch/i386/compile/TAME i386
Architecture: i386
Machine: i386
>Description:
        I'm using this machine as a NAT, and the related settings are: 

        map vr0 192.168.1.0/24 -> 0/32 proxy port ftp ftp/tcp
        map vr0 192.168.1.0/24 -> 0/32 portmap tcp/udp 40000:60000
        map vr0 192.168.1.0/24 -> 0/32
        
        I was transferring files with a Windows' WS_FTP, as the FTP connection
        froze. I reconnected and resumed the transfer, but after a minute or 
        so it froze again and the NAT box had paniced.
        
        Here's the output from trace: http://apz.fi/tmp/trace.jpg
>How-To-Repeat:
        Enable active FTP support, use FTP from any machine behind the NAT.
>Fix:
        Unknown. Workaround: disable active FTP support and use
        passive FTP.