我在Linux上有一个FTP服务器（ProFTPD 1.3.4b），在Windows上有一个FTPS客户端（MOVEit Freely 4.5.1.2 – Secure FTP Client）。
我这样连接
220 ProFTPD 1.3.4b Server (FTP with TLS) [1.2.3.4] 234 AUTH TLS successful Connected to my.ftp.server 232 User myaccount logged in 200 PBSZ 0 successful 200 Protection set to Private 215 UNIX Type: L8 然后像这样启动下载
ftp> get my.file 200 PORT command successful 150 Opening ASCII mode data connection for my.file (12345 bytes) 450 Transfer aborted. Link to file server lost Error: Failed to open data source. ftp: 0 bytes received in 0.02Seconds 0.00Kbytes/sec.
它失败。
如果不是get ...如上所示，我做的mget ...
ftp> prompt Interactive mode Off . ftp> mget my.file 200 PORT command successful 150 Opening ASCII mode data connection for file list ftp: 50 bytes received in 0.01Seconds 3.26Kbytes/sec. 226 Transfer complete 200 PORT command successful 150 Opening ASCII mode data connection for my.file (12345 bytes) 226 Transfer complete
它成功了。
远程文件的模式是：
-rw-r--r-- 1 someusr somegrp 12345 Sep 24 21:10 my.file
客户端可以在本地写入。
为什么get失败，并且mget不？
更新
针对等效会话的服务器日志（ tail -f xferlog access.log auth.log proftpd.debug.log proftpd_tls.log ）：
==> proftpd.debug.log <== Sep 25 19:17:37 my.ftp.server proftpd[30719] 1.2.3.4 (5.6.7.8[5.6.7.8]): FTP session opened. ==> proftpd_tls.log <== Sep 25 19:17:37 mod_tls/2.4.3[30719]: TLS/TLS-C requested, starting TLS handshake Sep 25 19:17:37 mod_tls/2.4.3[30719]: Client: DC = mydc1, DC = mydc2, OU = myou, CN = mycn Sep 25 19:17:37 mod_tls/2.4.3[30719]: TLSv1/SSLv3 connection accepted, using cipher some_cypher (x bits) Sep 25 19:17:37 mod_tls/2.4.3[30719]: Received user : myaccount my_cert_infos.... Sep 25 19:17:37 mod_tls/2.4.3[30719]: TLS/X509 cert mapping successful for user 'myaccount' ==> proftpd.debug.log <== Sep 25 19:17:37 my.ftp.server proftpd[30719] 1.2.3.4 (5.6.7.8[5.6.7.8]): USER myaccount: TLS/X509 cert mapping successful Sep 25 19:17:37 my.ftp.server proftpd[30719] 1.2.3.4 (5.6.7.8[5.6.7.8]): USER myaccount: Authenticated without password ==> auth.log <== [25/Sep/2015:19:17:39 +0200] FTP with TLS [30719] 5.6.7.8 "PASS (hidden)" 232 [25/Sep/2015:19:17:39 +0200] FTP with TLS [30719] 5.6.7.8 "USER myaccount" - ==> proftpd.debug.log <== Sep 25 19:17:39 my.ftp.server proftpd[30719] 1.2.3.4 (5.6.7.8[5.6.7.8]): USER myaccount: Login successful. ==> auth.log <== ==> proftpd_tls.log <== Sep 25 19:17:39 mod_tls/2.4.3[30719]: Protection set to Private Sep 25 19:17:59 mod_tls/2.4.3[30719]: starting TLS negotiation on data connection Sep 25 19:17:59 mod_tls/2.4.3[30719]: TLSv1/SSLv3 renegotiation accepted, using cipher some_cypher (x bits) Sep 25 19:17:59 mod_tls/2.4.3[30719]: TLSv1/SSLv3 data connection accepted, using cipher some_cypher (x bits) ==> xferlog <== Fri Sep 25 19:17:59 2015 0 5.6.7.8 0 my.file a _ or myaccount othergrp 0 * i ==> proftpd.debug.log <== Sep 25 19:17:59 my.ftp.server proftpd[30719] 1.2.3.4 (5.6.7.8[5.6.7.8]): notice: user myaccount: aborting transfer: Link to file server lost ==> access.log <== [25/Sep/2015:19:17:59 +0200] 5.6.7.8 myaccount "RETR my.file" 450 0 my.file ==> proftpd_tls.log <== Sep 25 19:18:07 mod_tls/2.4.3[30719]: starting TLS negotiation on data connection Sep 25 19:18:07 mod_tls/2.4.3[30719]: TLSv1/SSLv3 renegotiation accepted, using cipher some_cypher (x bits) Sep 25 19:18:07 mod_tls/2.4.3[30719]: starting TLS negotiation on data connection Sep 25 19:18:07 mod_tls/2.4.3[30719]: TLSv1/SSLv3 renegotiation accepted, using cipher some_cypher (x bits) ==> access.log <== [25/Sep/2015:19:18:07 +0200] 5.6.7.8 myaccount "RETR my.file" 226 12345 my.file ==> xferlog <== Fri Sep 25 19:18:07 2015 0 5.6.7.8 12345 my.file a _ or myaccount othergrp 0 * c