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I have a ProFTPD FTP server (Version: 1.3.4d (maint)) that works fine for existing files but hangs until a "FTP no transfer timeout" occurs if a non-existing file is requested.

This is what I see in proftpd.log when requesting a non-existing file:

May 20 12:05:04 myhost proftpd[25990] 1.2.3.4 (5.6.7.8[5.6.7.8]): FTP session opened. 
May 20 12:05:04 myhost proftpd[25990] 1.2.3.4 (5.6.7.8[5.6.7.8]): USER system: Login successful. 
...hangs for 10 Minutes....             
May 20 12:15:04 myhost proftpd[25990] 1.2.3.4 (5.6.7.8[5.6.7.8]): Passive data transfer failed, possibly due to network issues 
May 20 12:15:04 myhost proftpd[25990] 1.2.3.4 (5.6.7.8[5.6.7.8]): Check your PassivePorts and MasqueradeAddress settings, 
May 20 12:15:04 myhost proftpd[25990] 1.2.3.4 (5.6.7.8[5.6.7.8]): and any router, NAT, and firewall rules in the network path. 
May 20 12:15:04 myhost proftpd[25990] 1.2.3.4 (5.6.7.8[5.6.7.8]): FTP no transfer timeout, disconnected 
May 20 12:15:04 myhost proftpd[25990] 1.2.3.4 (5.6.7.8[5.6.7.8]): ROOT PRIVS: unable to setegid(): Operation not permitted 
May 20 12:15:04 myhost proftpd[25990] 1.2.3.4 (5.6.7.8[5.6.7.8]): RELINQUISH PRIVS: unable to seteuid(session.uid): Operation not permitted 
May 20 12:15:04 myhost proftpd[25990] 1.2.3.4 (5.6.7.8[5.6.7.8]): FTP session closed.

These are the timeouts configured in proftpd.conf:

TimeoutNoTransfer 600
TimeoutStalled 600
TimeoutIdle 1200

However, requests for existing files to the same server work fine.

Can anybody help me on this?

Jörn
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  • What does the FTP client see, in terms of commands/responses? – Castaglia May 24 '16 at 16:16
  • I use "edtftpj", a Java client. The client successfully connects to the FTP server, sets off its request for the non-existent file and than gets an exception after 60 seconds due to its socket timeout. This is the stack trace I see: `Caused by: java.io.IOException: /somedir/non_existing: No such file or directory at com.enterprisedt.net.ftp.AbstractFTPInputStream.start(AbstractFTPInputStream.java:117) at com.enterprisedt.net.ftp.AbstractFTPInputStream.start(AbstractFTPInputStream.java:95) at com.enterprisedt.net.ftp.FTPBinaryInputStream.read(FTPBinaryInputStream.java:139)` – Jörn May 24 '16 at 16:35
  • I was asking about the FTP commands/responses, not the stacktrace. But given that stacktrace, perhaps your client code needs to handle some of these errors in a different fashion? – Castaglia May 24 '16 at 16:59

1 Answers1

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My problem is in the FTP client side, not the FTP server. I built a small FtpTester test tool and can reproduce the problem, which seems to be a bug in EnterpriseDT's edtFTPj FTP client. If you open an FTPInputStream on a non-existing file and close() it after receiving an IOException, the close() operating hangs until the socket timeout occurs.

I described this in detail on EnterpriseDT's web site, cf. http://enterprisedt.com/questions/index.php/11407/ftpinputstream-close-hangs-until-socket-timeout

I solved my problem with this workaround: Before opening an FTPInputStream I explicity check if the file exists.

Jörn
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