• Config.ConnectTimeout - Time to wait (in milliseconds) for a connection attempt to succeed, before giving up. Default: 15000 (15 seconds).

• Config.ReadTimeout - Time to wait (in milliseconds) for data to be read from the FTP control stream, before giving up. Honored by all asynchronous methods as well. Default: 15000 (15 seconds).

• Config.DataConnectionConnectTimeout - Time to wait (in milliseconds) for an Active FTP data connection to be established, before giving up. Default: 15000 (15 seconds).

• Config.DataConnectionReadTimeout - Time to wait (in milliseconds) for the server to send data on the Active FTP data channel, before giving up. Does not affect data sent on the control channel or Passive FTP connections. Default: 15000 (15 seconds).

Just set Config.ReadTimeout before executing your FTP command and then set it back to whatever you want.

client.Config.ReadTimeout = 100;     // 100 ms timeout
client.Execute(..);                  // execute whatever command here, you can also use high level API
client.Config.ReadTimeout = 10000;   // 10 seconds timeout

Reason: stream.ReadLine is only called in 3 places for Execute, and all of them honor Config.ReadTimeout.

For a client on windows, please also read the following:

Special considerations for windows timeout setting