commons-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "daniel damon (JIRA)" <>
Subject [jira] Created: (NET-363) Can't connect to a server behind firewall in passive mode
Date Fri, 04 Mar 2011 23:12:47 GMT
Can't connect to a server behind firewall in passive mode

                 Key: NET-363
             Project: Commons Net
          Issue Type: Bug
          Components: FTP
    Affects Versions: 2.2
         Environment: Windows Client with Zos mainframe server behind a firewall.  However
I think any client/server will demonstrate the issue as long as the server is behind a firewall.
            Reporter: daniel damon
            Priority: Blocker

When the FTP server is behind a firewall, FTPClient can connect, but it cannot transfer data.
This is because the FTP server provides it's own address instead of the firewall address to
make the connection. I have confirmed the problem by hacking a copy of FTPClient to set the
__passiveHost to the appropriate internet address. With this hack, I can transfer data.

Perhaps the FTP server could be configured differently to fix the issue. Unfortunately, I
do not have access to the server configuration. I do know that the commercial product IpswitchFtp
does deal with the issue as this extract from it's log shows:
227 Entering Passive Mode (192,168,13,11,195,129)
connecting data channel to,129(50049)
Substituting connection address for private address from PASV
data channel connected to,129(50049)
125 List started OK
transferred 4157 bytes in 0.078 seconds, 425.688 kbps ( 53.211 kBps), transfer succeeded.
250 List completed successfully.
I can take a shot at a fix if you want. I'll set some timeout, and  if that fails, I'll use
the original address

This message is automatically generated by JIRA.
For more information on JIRA, see:


View raw message