Can the same sever accept both Explicit and Implicit FTPS?

Question

I am using VSFTPD on an Ubuntu server.

I have 2 clients who want to connect to this FTP server, one of them uses FTPS with Explicit Authentication and the other client uses FTPS with implicit authentication.

Is there anyway that could configure VSFTPD, to accept both Implicit and Explicit authentications?

Here is my /etc/vsftpd.conf:

listen=NO
listen_ipv6=YES
anonymous_enable=NO
local_enable=YES
write_enable=YES
dirmessage_enable=YES
use_localtime=YES
xferlog_enable=YES
connect_from_port_20=NO
# pasv_address=13.55.13.221 
idle_session_timeout=1200
data_connection_timeout=3600
accept_timeout=500
connect_timeout=5000
allow_writeable_chroot=YES
chroot_local_user=YES
user_sub_token=$USER
local_root=/home/$USER/uploads
pasv_enable=YES
pasv_min_port=40000
pasv_max_port=50000
userlist_enable=YES
userlist_file=/etc/vsftpd.userlist
userlist_deny=NO
secure_chroot_dir=/var/run/vsftpd/empty
pam_service_name=vsftpd
rsa_cert_file=/etc/ssl/private/vsftpd.pem
rsa_private_key_file=/etc/ssl/private/vsftpd.pem
ssl_enable=YES
allow_anon_ssl=NO
force_local_data_ssl=YES
force_local_logins_ssl=YES
ssl_tlsv1=YES
ssl_sslv2=NO
ssl_sslv3=NO
require_ssl_reuse=NO
ssl_ciphers=HIGH
utf8_filesystem=YES

You will probably need to have two instances of VSFTPD that list in on two different ports with different configurations. — Moshe Katz, Dec 06 '21 at 23:57
@MosheKatz: thanks, so does it mean I need 2 physical servers? — Hooman Bahreini, Dec 07 '21 at 00:24
No, you should be able to run two instances of the software on the same server. You just need to set them to use different ports. — Moshe Katz, Dec 07 '21 at 00:28

score 2 · Accepted Answer · answered Dec 07 '21 at 07:04

As the documentation for implicit_ssl says:

To support explicit SSL and/or plain text too, a separate vsftpd listener process should be run.

For that see:
How do you setup multiple instances of vsftpd to run on different listen ports?

Though note that the implicit TLS/SSL is a legacy hack introduced decades ago to ease transitioning to encrypted FTP, at the times, when FTP clients did not have a built-in support for TLS/SSL. It shall not be used today. So the requirements of one of your client to use it, seems strange. I know of no FTP client that would support only implicit TLS and not explicit TLS.

Can the same sever accept both Explicit and Implicit FTPS?

1 Answers1