Why am I getting a "Listing remote folder failed" error when I try to connect with SFTP?

Question

I set up SFTP, but I have a problem regarding iptables. Here are my rules:

A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 21 -j ACCEPT
A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 20 -j ACCEPT
A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 21 -j ACCEPT

By the way, I'm using the vsftpd service for FTP. So, it's not connecting to FTP, before stopping iptables service. When I attempt to connect to FTP, that's gives me "Listing remote folder failed" error.

What should I do?

Answer 1

SFTP and FTP are not the same thing.

If you really mean SFTP, that's an SSH-based transmission that takes place only over port 22 (unless you configure your SSH daemon to listen on another port).

FTP is an ancient file-transfer protocol that operates on ports and 21 (and possibly others). Firewalls need to do connection state-tracking to properly support it. Make sure you have the netfilter ftp connection tracking module (nf_conntrack_ftp) loaded.

You can configure the min/max ports for "passive mode" FTP in vsftp via the pasv_min_port and pasv_max_port options in vsftpd.conf: Could you narrow the range down to a small number of ports (perhaps one port) and open them in the firewall?

Are you sure the firewall is at fault? If you disable it temporarily, do things work?