[Samba] Not another SAMBA through a firewall post

[Mike]

NAT relies on port forwarding.  To do pre/post routing, I believe you
must indicate FORWARDING rules for incoming and outgoing traffic on
that port:

$IPT -t filter -A FORWARD -i $INTIF -o $EXTIF -p tcp --dport 137 --syn
-m state --state NEW -j ACCEPT
$IPT -t filter -A FORWARD -o $INTIF -i $EXTIF -p tcp --dport 137 --syn
-m state --state NEW -j ACCEPT

$IPT -t filter -A FORWARD -i $INTIF -o $EXTIF -p tcp --dport 138 --syn
-m state --state NEW -j ACCEPT
$IPT -t filter -A FORWARD -o $INTIF -i $EXTIF -p tcp --dport 138 --syn
-m state --state NEW -j ACCEPT

$IPT -t filter -A FORWARD -i $INTIF -o $EXTIF -p tcp --dport 139 --syn
-m state --state NEW -j ACCEPT
$IPT -t filter -A FORWARD -o $INTIF -i $EXTIF -p tcp --dport 139 --syn
-m state --state NEW -j ACCEPT

$IPT -t filter -A FORWARD -i $INTIF -o $EXTIF -p tcp --dport 445 --syn
-m state --state NEW -j ACCEPT
$IPT -t filter -A FORWARD -o $INTIF -i $EXTIF -p tcp --dport 445 --syn
-m state --state NEW -j ACCEPT

Do you have similar forwarding rules?
HTH,
Mike