"530 No transfer-slave(s) available" is a msg given when the drftpd master is unable to negotiate (or find) a slave that is able to send the file. 
 
Examples of a fully working drftpd setup... (Site R is drftpd, Site L is Serv-U 6.1) 
-listing 
[18:33:01] [R] PRET LIST 
[18:33:02] [R] 200 OK, will use master for upcoming transfer 
[18:33:02] [R] PASV 
[18:33:02] [R] 227 Entering Passive Mode (*,*,*,*,*,*). 
[18:33:02] [R] Opening data connection IP: *.*.*.* PORT: * 
[18:33:02] [R] LIST 
[18:33:02] [R] 150 File status okay; about to open data connection. 
[18:33:03] [R] 226- *** quota and credits stuff 
[18:33:03] [R] 226 Closing data connection 
[18:33:03] [R] List Complete: 1,014 bytes in 1.75 second (0.6 KB/s) 
 
-download fxp 
[18:53:05] [R] PRET RETR *** 
[18:53:05] [R] 200 OK, will use *** for upcoming transfer 
[18:53:05] [R] PASV 
[18:53:06] [R] 227 Entering Passive Mode (*,*,*,*,*,*). 
[18:53:06] [L] PORT *,*,*,*,*,* 
[18:53:06] [L] 200 PORT Command successful. 
[18:53:06] [L] STOR *** 
[18:53:06] [L] 150 Opening BINARY mode data connection for ***. 
[18:53:06] [R] RETR *** 
[18:53:06] [R] 150 File status okay; about to open data connection from ***. 
[18:53:18] [R] 226- Checksum from transfer: 61ce3c26 
[18:53:18] [R] 226 Transfer complete, 5.1MB in 11.673 seconds (439.4KB/s) 
[18:53:19] Transferred: zwtvw509.zip 5,128,788 bytes in 12.28 seconds (407.8 KB/s) 
 
-upload fxp 
[18:56:36] [L] PASV 
[18:56:36] [L] 227 Entering Passive Mode (*,*,*,*,*,*) 
[18:56:36] [R] PORT *,*,*,*,*,* 
[18:56:36] [R] 200 FXP allowed. If you're not FXPing then set your IP to *.*.*.* (usually in firewall settings) 
[18:56:36] [R] STOR x.zip 
[18:56:37] [R] 150 File status okay; about to open data connection to ***. 
[18:56:37] [L] RETR x.zip 
[18:56:37] [L] 150 Opening BINARY mode data connection for x.zip (5000000 Bytes). 
[18:56:43] [L] 226 Transfer complete. 
[18:56:43] [R] 226 Transfer complete, 5.0MB in 5.86 seconds (853.2KB/s) 
[18:56:43] Transferred: x.zip 5,000,000 bytes in 5.84 seconds (835.7 KB/s)
		 
		
		
		
		
		
		
		
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