How to disable SSLv2 and SSLv3 in pure-ftpd

Question

I am running pure-ftpd like this:

/usr/sbin/pure-ftpd -A -c10 -B -C3 -z -D -e -fftp -H -I15 -lpam -L2000:8 -m4 -p30000:30100 -s -u40 -x -r -i -k99 -G -Z -Y1 -J'HIGH:MEDIUM:+TLSv1:!SSLv2:!SSLv3'

but in syslog-ng monitoring I get an error:

pure-ftpd: (?@?) [ERROR] SSL/TLS: Invalid TLSCipherSuite specified 'HIGH:MEDIUM:+TLSv1:!SSLv2:!SSLv3'

I tried several variations without any luck. The only one that worked without a problem it was this one (in the configuration file):

TLSCipherSuite          HIGH:MEDIUM:+TLSv1:!SSLv2:+SSLv3

then run:

/usr/sbin/pure-config.pl /etc/pure-ftpd/pure-ftpd.conf

Running: /usr/sbin/pure-ftpd -A -c10 -B -C3 -d -z -D -e -fftp -H -I15 -lpam -L2000:8 -m4 -p30000:30100 -s -u40 -x -r -i -k99 -G -Z -Y1 -JHIGH:MEDIUM:+TLSv1:!SSLv2:+SSLv3

but with this one, only SSLv2 is disabled.

I found this command at: http://download.pureftpd.org/pub/pure-ftpd/doc/README and there is says:

'-J ': Sets the list of ciphers that will be accepted for SSL/TLS connections.

For example: -J HIGH:MEDIUM:+TLSv1:!SSLv2:+SSLv3

Prefixing the list with -S: totally disables SSLv3.

I think this -S might solve my problem but I can't figure out how to use it.

Answer 1

To be able to disable SSLv* and use TLS instead, this is what I does with version 1.0.33 and 1.0.38 :

Put this in /usr/sbin/pure-ftpd-wrapper.patch (or replace -J global switch by -S):

--- pure-ftpd-wrapper   2012-10-29 10:45:31.000000000 +0000
+++ pure-ftpd-wrapper.modified  2015-11-12 15:23:31.104156082 +0000
@@ -87,6 +87,7 @@
            'Quota' => ['-n %d:%d', \&parse_number_2],
            'SyslogFacility' => ['-f %s', \&parse_word, 99],
            'TLS' => ['-Y %d', \&parse_number_1],
+           'TLSCipherSuite' => [ '--tlsciphersuite=-S%s', \&parse_string],
            'TrustedGID' => ['-a %d', \&parse_number_1],
            'TrustedIP' => ['-V %s', \&parse_ip],
            'Umask' => ['-U %s:%s', \&parse_umask],

then :

cd /usr/sbin
patch < pure-ftpd-wrapper.patch && rm -f pure-ftpd-wrapper.patch

and :

cat<<EOF>/etc/pure-ftpd/conf/TLSCipherSuite
:ALL:!aNULL:!eNULL:!LOW:!EXP:!RC4:!3DES:!SEED-SHA:!DHE-RSA-SEED-SHA:+HIGH+MEDIUM
EOF

Or your own classic openssl configuration.

then, run a ssl test with testssl :

./testssl --starttls ftp YOUR-FTPS-DOMAIN:21

and you expect especially this :

 SSLv2      not offered (OK)
 SSLv3      not offered (OK)
 TLS 1      offered
 TLS 1.1    offered
 TLS 1.2    offered (OK)

To understand why -S (disable ssl, not documented) instead of -J, you have to read this changelog. :

• Add SSL_OP_NO_SSLv3 to SSL options if the list of ciphers is prefixed by -S: , needed by Brad.

Answer 2

You should try the following format:

-S:HIGH:MEDIUM:+TLSv1