[SOLVED] Proxy FTP behind linux firewall using iptables
Linux - NetworkingThis forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
If you have any problems with the registration process or your account login, please contact us. If you need to reset your password, click here.
Having a problem logging in? Please visit this page to clear all LQ-related cookies.
SDN 101: An Introduction to Software Defined Networking
Discover the advantages of SDN.
SDN has quickly become one of the hottest trends in IT. But not all SDN solutions offer real software-defined functionality. As more enterprises consider SDN, they want to know, “What is SDN? And what are the real benefits?” If you're ready to explore the advantages of SDN, and want to know how it should be implemented within your enterprise, start by reading our introductory white paper.
Click Here to receive this Complete Guide absolutely free.
FTP Server (CentOS 5.4)
eth0: 10.0.0.10/24 (Private-facing if)
PassivePorts 60000 65535
I can get Active FTP working using HAProxy, but Passive FTP is a no go. Here's what I've tried so far on the firewall server:
iptables -t nat -A POSTROUTING -s 10.0.0.10/32 -o bond1 -j SNAT --to-source 22.214.171.124
iptables -t nat -A PREROUTING -d 126.96.36.199/32 -i bond1 -p tcp -m tcp --dport 60000:65535 -j DNAT --to-destination 10.0.0.10
When I connect to 188.8.131.52 with ftp, I can log in, but I can't get data to transfer. Example output:
220 FTP Server ready.
331 Password required for crinis
230 User crinis logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
229 Entering Extended Passive Mode (|||63627|)
ftp: Can't connect to `184.108.40.206': Connection refused
500 Illegal PORT command
421 Service not available, remote server has closed connection.
I have seen some discussion on loading ip_nat_ftp and ip_conntrack_ip, but enabling those on either or both hosts has no effect.
If it's relevant, the following iptable rules are already in place for HAProxy
iptables -A FORWARD -i bond0 -j ACCEPT
iptables -A FORWARD -o bond0 -j ACCEPT
iptables -t nat -A POSTROUTING -o bond1 -j MASQUERADE
Also, Active FTP with iptables instead of HAProxy would be a plus. Thanks!
Well I have never attempted but I think your problem here is the way a passive data connection is established with passive ftp.
When working at a Web Hosting company we ran into a similar issue with a new network config and implemented the ip_conntrack and ip_conntrack_ftp modules. A nifty little article was written up about it here:
Ha ha! I solved it. I was googling the wrong problem. "FTP NAT IPTABLES" were the criteria I should have been using. For further information, here's the solution, all executed on the firewwall side. This solution also eliminates the need to use HAProxy for FTP Active.