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You may encounter an error code indicating that FTP error 500 is an invalid port. Well, there are a number of steps you can take to fix this issue and we will get back to that shortly. Actually 500 is a short FTP error code, not a port number or anything more descriptive. The default recovery is to enter “pass” (passive) instructions after logging in. With FTP active, servers try to connect from port 20 to a higher port on the patient side to send data.
First, the last two instructions, PORT and PASV, are not related. Two of these are usually independent connection attempts (one for the current FTP, one for passive FTP).
What does port 500 mean on an FTP server?
500 is a quick FTP error code, maybe not a port number or something else meaningful. The standard solution is to enter the “pass” (passive) command immediately after authorization. This should cause the FTP server to also use your control word channel to transfer returned data.
PORT route works (“FTP active” mode), the client sends its address to the Internet computer – the server reconnects to you for this data transfer.
According to his logs, your client computer is behind NAT and has a “private” IP address. This is the only help it knows, so understand what it sends with the PORT command.
Normally your entire router sees the FTP link and silently changes the PORT, replacing your private address with the router’s own public address. (Or, if you’re unlucky, you can replace what’s what with garbage.)
However, since your control web link is now encrypted with TLS, the whole router can’t do this fix (everything it sees is encrypted plus data), the server gets exactly what your favorite client sends: your private address .
Because the real server is online, another server might not be able to access the product with a private response (that’s the whole point of NAT). While this won’t even bother the user – for security reasons, mostThese jars will simply reject any address that doesn’t exactly match the address from which the connection was made.
tl;dr You switch the FTP client to passive mode. Yes, there is also a log that the passive mode (PASV) is compromised. But at least it’s fixable if your computer has a dedicated public IP address that’s active while the mode isn’t in use.
Normally, your server’s firewall will listen for a particular FTP connection, extract the forward port from the “Passive Policy Entry (x,y,z…)” response, and mark it as belonging to a “BINDING” connection. . Then your rule number 004 will allow you to do this.
Again, iptables cannot see over TLS (all it sees is secure data) and can no longer recognize actual FTP data connections as connected. So your connection only reaches theory #999 and breaks.
In order to use PASV, you need to configure ProFTPd to indirectly use a certain range of ports (no matter how many) and allow iptables to connect to those ports.
Pri 5 encoding = “ISO-8859-1”