krb5-clients: ftp gives spurious permanent error

krb5-clients: ftp gives spurious permanent error

[Francesco Potorti`]

Package: krb5-clients
Version: 1.2.4-5
Severity: normal

Since installing the kerberos 5 clients on a Debian system, Emacs'
ange-ftp has gotten confused by this message:

root@pot# ftp ftp.it.debian.org
Connected to ftp.bofh.it.
220 ready, dude (vsFTPd 1.0.0: beat me, break me)
530 Please login with USER and PASS.
530 Please login with USER and PASS.
KERBEROS_V4 rejected as an authentication type
Name (ftp.it.debian.org:pot):

As you see, before the prompt, two 530 messages are given, which can be
safely ignored.  Unfortunately, ange-ftp takes them seriously and fails.

According to RFC 959, however, ange ftp is correct, because a 5xy error
is a permanent error.  Is that indeed the case?  Is the kerberised ftp
wrong?  I think so.

-- System Information
Debian Release: 3.0
Kernel Version: Linux pot.cnuce.cnr.it 2.4.18 #1 Fri May 17 13:44:40 CEST 2002 i686 unknown

Versions of the packages krb5-clients depends on:
ii  e2fsprogs      1.27-2         The EXT2 file system utilities and libraries
ii  krb5-config    1.4            Configuration files for Kerberos Version 5
ii  libc6          2.2.5-10       GNU C Library: Shared libraries and Timezone
ii  libkrb53       1.2.4-5        MIT Kerberos runtime libraries
ii  libncurses5    5.2.20020112a- Shared libraries for terminal handling
ii  e2fsprogs      1.27-2         The EXT2 file system utilities and libraries
	^^^ (Provides virtual package libcomerr2)

Re: Bug#154252: krb5-clients: ftp gives spurious permanent error

[Francesco Potorti`]

I just discovered that the problem is cured by using a "-u" option to
ftp, instead of the normal "-n" that ange-ftp uses.

"-u" means "do not auto-athenticate and do not auto-login"

It may be argued that the kerberised ftp should not try to authenticate
when given the "-n" option, for compatibility with traditional ftp, that
is, -n should do the same as -u.

The way the kerberised ftp currently behaves is incompatible with ftp,
and a program using it (ange-ftp) should first test it to see which
version it is.  

Or else ignore those specific 530 messages at startup.

Re: krb5-clients: ftp gives spurious permanent error

[Eric Marsden]

the following thread discussed the problem, and led to a patch that I
believe was applied to Emacs 20.7, but that does not seem to have been
taken to the Emacs 21 branch.

  <URL:http://groups.google.com/groups?threadm=wzipuqwdf3y.fsf%40mail.dotcom.fr>

-- 
Eric Marsden                          <URL:http://www.laas.fr/~emarsden/>

Re: krb5-clients: ftp gives spurious permanent error

[Francesco Potorti`]

     <URL:http://groups.google.com/groups?threadm=wzipuqwdf3y.fsf%40mail.dotcom.fr>

That one should do the trick, except that we have a 530 error message
rather than a 500.

Re: Bug#154252: krb5-clients: ftp gives spurious permanent error

[Richard Stallman]

    I just discovered that the problem is cured by using a "-u" option to
    ftp, instead of the normal "-n" that ange-ftp uses.

    "-u" means "do not auto-athenticate and do not auto-login"

You can set ange-ftp-ftp-program-args to specify -n.
Is that sufficient, or do you want some further feature?

    The way the kerberised ftp currently behaves is incompatible with ftp,
    and a program using it (ange-ftp) should first test it to see which
    version it is.  

I don't know whether this is a feasible thing to do, but if someone
implements it and it works smoothly, this would be good to install.

Re: krb5-clients: ftp gives spurious permanent error

[Richard Stallman]

    the following thread discussed the problem, and led to a patch that I
    believe was applied to Emacs 20.7, but that does not seem to have been
    taken to the Emacs 21 branch.

Can you recommend a specific patch?

Re: krb5-clients: ftp gives spurious permanent error

[Francesco Potorti`]

Accessing some ftp servers with ange-ftp when a kerberised ftp is
installed may lead to problems due to unanticipated responses from the
server.

The following patch cures the problem that I observed.
If it is okay, I can install it.


2002-08-27  Francesco Potorti`  <pot@gnu.org>

	* net/ange-ftp.el (ange-ftp-skip-msgs): Skip the 530 response
	given by vsFTPd when accessed with a kerberised FTP client.

Index: ange-ftp.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/net/ange-ftp.el,v
retrieving revision 1.43
diff -p -u -p -u -b -r1.43 ange-ftp.el
--- ange-ftp.el	14 Aug 2002 22:43:46 -0000	1.43
+++ ange-ftp.el	27 Aug 2002 14:18:05 -0000
@@ -728,6 +728,7 @@ parenthesized expressions in REGEXP for 
 	  "^Data connection \\|"
 	  "^local:\\|^Trying\\|^125 \\|^550-\\|^221 .*oodbye\\|"
          "^500 .*AUTH \\(KERBEROS\\|GSSAPI\\)\\|^KERBEROS\\|"
+	  "^530 Please login with USER and PASS\\|" ; non kerberised vsFTPd
 	  "^22[789] .*[Pp]assive\\|^200 EPRT\\|^500 .*EPRT")
   "*Regular expression matching ftp messages that can be ignored."
   :group 'ange-ftp

Re: krb5-clients: ftp gives spurious permanent error

[Richard Stallman]

Thanks.  I installed this fix.