commit 133004297a1a39dcbe6fa8f398cc8070627541de (refs/remotes/origin/v3.5)
Author: Rybakov Andrey <rybakovandrey85@gmail.com>
Date:   2018-02-02 18:26:34 +0300

    Fixed "Cannot assign requested address" for to-origin TPROXY FTP data (#142)

diff --git a/src/clients/FtpClient.cc b/src/clients/FtpClient.cc
index 6f5e4f8..70d88d6 100644
--- a/src/clients/FtpClient.cc
+++ b/src/clients/FtpClient.cc
@@ -761,6 +761,8 @@ Ftp::Client::connectDataChannel()
     conn->remote.port(data.port);
     conn->tos = ctrl.conn->tos;
     conn->nfmark = ctrl.conn->nfmark;
+    // Using non-local addresses in TPROXY mode requires appropriate socket option.
+    conn->flags |= ctrl.conn->flags & COMM_TRANSPARENT;
 
     debugs(9, 3, "connecting to " << conn->remote);