Bug#980119: libgnutls30: "An unexpected TLS packet was received" when connecting to FTPS (FTP/TLS) servers

[Boyd Stephen Smith Jr.]

Package: libgnutls30
Version: 3.7.0-5
Severity: normal

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Dear Maintainer,

Trying to upload some files to a game hosting provider that only allows FTPS
(not SFTP) access.  Provider is akliz.net.

Each customer gets a private virtual (vsftp?) instance.  I'm connecting to
bos-sr-2-36.akliz.net

In both FileZilla 3.51.0-1 and lftp 4.8.4-2+b1 I get an error _after_ a
successful login when trying to list the contents of the current directory.

In FileZilla, this shows as a number of red error messages ending with "GnuTLS
error -15 in gnutls_record_recv: An unexpected TLS packet was received."  In
lftp, this shows as a single filure line: "Fatal error: gnutls_record_recv: An
unexpected TLS packet was received."

Due to the failure in multiple front ends, I believe this is a library issue.

Prior to upgrading to bullseye/sid, I was able to use FileZilla to connect to
the same private virtual server from the same provider.  So, I believe this is
a regression from working behavior of GNUTLS in buster.

Please let me know the best way to collect any further documentation that might
be helpful, I can reproduce the issue at will.

- -- System Information:
Debian Release: bullseye/sid
  APT prefers testing-debug
  APT policy: (900, 'testing-debug'), (900, 'stable-updates'), (900, 'stable-debug'), (900, 'testing'), (900, 'stable'), (850, 'proposed-updates-debug'), (850, 'proposed-updates'), (500, 'unstable-debug'), (500, 'unstable'), (300, 'experimental-debug'), (300, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.9.0-5-amd64 (SMP w/16 CPU threads)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8), LANGUAGE=en_US
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages libgnutls30 depends on:
ii  libc6          2.31-9
ii  libgmp10       2:6.2.1+dfsg-1
ii  libhogweed6    3.6-2
ii  libidn2-0      2.3.0-4
ii  libnettle8     3.6-2
ii  libp11-kit0    0.23.22-1
ii  libtasn1-6     4.16.0-2
ii  libunistring2  0.9.10-4

libgnutls30 recommends no packages.

Versions of packages libgnutls30 suggests:
ii  gnutls-bin  3.7.0-5

- -- no debconf information

-----BEGIN PGP SIGNATURE-----

iHQEARECADQWIQTFhn3a8g2plxzZYyjnmmovsbVAWQUCYACD8RYcYnNzQGlndWFu
YXN1aWNpZGUubmV0AAoJEOeaai+xtUBZSCsAn2t2l5yMNo+8bVxy02EiBr5SxlUt
AJ49lFmU8Yi3kRby2+7bbv3O0kZoqQ==
=EL1C
-----END PGP SIGNATURE-----