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My client has laptops that shared by staff.
#Passive ftp ports to open software#
Office license on a shared computer Software.Does anyone have any real world experience with the number of ports that I can allocate to this passive configuration, that will not be too small or too big? Thanks in advanced to all those that respond.
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I have googled for hours trying to find a best practices of the quantity of ftp passive ports to be used, but have not come back with anything conclusive. I do not want to limit them too much, as some of the sessions might need to be left open for 2 hours because of large uploads/downloads. When I look at my wireshark data I see that just in 60 seconds, that I have already used 2 - 4 passive ports. I have to take into consideration the total number of ftp instances allowed on the ftp server currently set to 30. To many, and it becomes a big hole in the firewall. Too few, and it will affect the quality of the ftp service. I am looking for some best practices as it pertains to the number of ftp passive ports to have left open on our firewall. This is a potential security issue and it isn't advisable to use the Passive mode of FTP.While I understand Active vs Passive FTP setups. This method of FTP is insecure, as a random unprivileged port is opened on the Server. The client then initiates the connection from port no. The result of this is that the server then opens a random unprivileged port, let us say P, and sends the PORT command back to the client. 21, but instead of then issuing a PORT command and allowing the server to connect back to its data port, the client will issue the PASV command. The first port contacts the server on port no. When opening an FTP connection, the client opens two random unprivileged ports, let us say N and N+1. In passive mode FTP, the FTP client initiates both connections to the server. Here in this mode of FTP, we do not need to open any additional non-secure ports on our servers firewall and hence is secure from the server-side.
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The server will then connect back to the client's specified data port from its local data port, which is port no. Then, the client starts listening to port N+1 and sends the FTP command PORT N+1 to the FTP server. Let us say N is the FTP server's command port, port no. In active mode FTP, the FTP client software connects from a random unprivileged (unprivileged port is a port which is higher than 1023) port. The confusion begins however, when we find that depending on the mode, the data port is not always on port 20. Traditionally these are port 21 for the Command (Control) port and port 20 for the Data port. FTP is an unusual service in that it utilizes two ports, a Data port and a Command port (also known as the Control port).
![passive ftp ports to open passive ftp ports to open](https://vk9-sec.com/wp-content/uploads/2020/04/ftp-active-vs-passive-mode-3.gif)
Using these two communication connections, two distinct modes of operation determine in which direction the connections are established - Active mode and Passive mode.įTP is a TCP based service exclusively.