Tool/software: Linux
Hi,
I have 2 devices (both AM3352) - one is for processing the data (let's call it MAIN), the other is for LCD, buttons and user interface (I'll refer to this one as HMI). Both are connected to each other with ppp (tun/tap) interface over RS422. On HMI is installed ftp server (vsftp to be specific), working in passive mode. I have to forward the connection coming to eth0 of MAIN thru ppp0 interface to ftp server on HMI.
Normally I would put this problem on some stack(Overflow/Exchange/Whatever), but I have reproduced my problem on VMs (I had working ftp on windows10 vm and new lubuntu for iptables) and my solution is working on desktops.
Here is my setup: (on VMs interfaces names and IPs are changed, rest is same)
## raw iptables -t raw -A PREROUTING -p tcp -m tcp --dport 21 -j CT --helper ftp ## filter iptables -A FORWARD -d 192.168.201.1/32 -p tcp -m tcp --dport 21 -j ACCEPT ## nat iptables -t nat -A PREROUTING -p tcp -m tcp --dport 21 -j DNAT --to-destination 192.168.201.1:21 iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE # cat /proc/sys/net/netfilter/nf_conntrack_helper 0 # cat /proc/sys/net/ipv4/ip_forward 1 # modprobe nf_nat_ftp # lsmod Module Size Used by nf_nat_ftp 1839 0 nf_conntrack_ftp 6534 2 nf_nat_ftp xt_CT 3205 1 iptable_raw 1510 1 xt_conntrack 2886 0 iptable_filter 1808 1 ipt_MASQUERADE 1102 1 nf_nat_masquerade_ipv4 2734 1 ipt_MASQUERADE xt_nat 1671 1 xt_tcpudp 2137 3 iptable_nat 1803 1 nf_conntrack_ipv4 6580 2 nf_defrag_ipv4 1435 1 nf_conntrack_ipv4 nf_nat_ipv4 5261 1 iptable_nat nf_nat 15612 4 xt_nat,nf_nat_ftp,nf_nat_masquerade_ipv4,nf_nat_ipv4 nf_conntrack 76225 8 nf_conntrack_ftp,nf_conntrack_ipv4,nf_nat_ftp,xt_CT,nf_nat_masquerade_ipv4,xt_conntrack,nf_nat_ipv4,nf_nat ip_tables 11523 3 iptable_filter,iptable_raw,iptable_nat x_tables 18629 8 xt_nat,ip_tables,iptable_filter,xt_tcpudp,iptable_raw,ipt_MASQUERADE,xt_CT,xt_conntrack
to connect I'm using filezilla - connection time outs after some time - to be sure I have same setup I have cloned setting and changed IP for both VM and am335x setups.
While connecting to HMI directly ftp is working fine.
I am using kernel: 4.9.50
from git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git
commit: 4ad5dcaca7428dd2bc1a6a40c948e3799c1e27ae
I have also tried using two am335x connected with eth interface - same here so it's probably not ppp problem.
I'l be realy glad if you can at least show me some direction to look for an answer.
Kind regards,
Marek
