Description of problem: With --disable-epsv, curl should not attempt to use EPSV mode no matter what. When the host name in URL is 'localhost' or 'localhost.localdomain', EPSV is not disabled. On the other hand, when 127.0.0.1 is used instead, --disable-epsv is respected. Version-Release number of selected component (if applicable): curl-7.19.7-51.el6.x86_64 Steps to reproduce: # yum -y install vsftpd # echo OK > /var/ftp/pub/test # service vsftpd start # curl -v --disable-epsv ftp://localhost/pub/test Actual results: > EPSV * Connect data stream passively < 229 Entering Extended Passive Mode (|||20246|). * Trying 127.0.0.1... connected Expected results: > PASV * Connect data stream passively < 227 Entering Passive Mode (127,0,0,1,251,224). * Trying 127.0.0.1... connected
Hi, according to several resources curl option --disable-epsv has no effect for IPv6 hosts. For curl-7.19.7-51.el6 it works OK for localhost4 and also for localhost together with curl --ipv4 option. See e.g. https://curl.haxx.se/libcurl/c/CURLOPT_FTP_USE_EPSV.html ... If the server is an IPv6 host, this option will have no effect as of 7.12.3 ...
Thanks for the explanation. Still, I think this peculiarity should be documented right in curl man page shipped in RHEL at the very least.
Eva, thank you for replying on this! I believe the behavior is already documented in the RHEL-6 man page. $ rpm -q libcurl-devel libcurl-devel-7.19.7-46.el6.i686 $ man curl_easy_setopt | grep -A8 CURLOPT_FTP_USE_EPSV CURLOPT_FTP_USE_EPSV Pass a long. If the value is 1, it tells curl to use the EPSV command when doing passive FTP downloads (which it always does by default). Using EPSV means that it will first attempt to use EPSV before using PASV, but if you pass zero to this option, it will not try using EPSV, only plain PASV. If the server is an IPv6 host, this option will have no effect as of 7.12.3. See also: https://github.com/curl/curl/commit/0966ddaf
I would still argue that a man page provided by a devel subpackage is not the most fortunate place to provide this information. Not for a user who does not give a tinker's cuss about the internal affairs of curl and only cares about the command-line interface and the man page shipped with it. Obviously, this is a not a high priority bug which ought to be fixed on a short notice. Nonetheless, I believe adding that one sentence to curl man page still does make sense.
upstream commit: https://github.com/curl/curl/commit/curl-7_47_1-30-g4ef6b2d
RHEL-6 is in Production Phase 2, which means that only critical and security bugs are fixed. The current documentation is technically correct. Additional documentation improvements on this topic will be included in RHEL-7.