Yum, FTP, NFS & Internal Firewall

Bryan Sant bryan.sant at gmail.com
Fri Jun 17 10:53:26 MDT 2005

On 6/16/05, Charles Curley <charlescurley at charlescurley.com> wrote:
> If I use system-config-securitylevel to set up a minimum firewall,
> allowing only SSH, FTP and DNS, DNS works fine. ncftp simply falls
> back to port instead of passive mode, and continues to work. Yum fails
> as follows:

Charles, I have your solution.

> -A RH-Firewall-1-INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
Good, you're filtering on the RELATED state.

Just modprobe ip_conntrack_ftp as root and you should be in ship shape.

That kernel module will notice when an FTP PORT request is received
and realize that the new data port is *related* to your FTP connection
-- thus ACCEPT.

This will only work for FTP sessions initiated from this server.  If
you're NATing other hosts behind this, then you'll need to look into
the ip_nat_ftp.ko module.


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