Happy 2019!!

Lately I’ve been playing around with docker and decided to create a dockerfile to have vsftpd running on CentOS. Below is my dockerfile:

# Dockerfile for vsftpd on CentOS
FROM centos:7

MAINTAINER xavi@xavignu.com

RUN yum -y update; yum -y install which vsftpd net-tools vsftpd-sysvinit; yum clean all

COPY vusers.txt /etc/vsftpd/
RUN db_load -T -t hash -f /etc/vsftpd/vusers.txt /etc/vsftpd/vsftpd-virtual-user.db; rm -v /etc/vsftpd/vusers.txt; \ 
	chmod 600 /etc/vsftpd/vsftpd-virtual-user.db
COPY vsftpd.conf /etc/vsftpd/
COPY vsftpd.virtual /etc/pam.d/
RUN mkdir -p /home/vftp/ftpuser; chown -R ftp:ftp /home/vftp

EXPOSE 20 21

CMD ["/usr/sbin/vsftpd","-obackground=NO"]

We need to create three files before building the image, one for vsftpd virtual users PAM, another vsftpd.conf file and another with the virtual users. vsftpd.conf below:

anonymous_enable=NO
local_enable=YES
virtual_use_local_privs=YES
write_enable=YES
local_umask=022
pam_service_name=vsftpd.virtual
guest_enable=YES
user_sub_token=$USER
local_root=/home/vftp/$USER
chroot_local_user=YES
allow_writeable_chroot=YES
hide_ids=YES
xferlog_enable=YES
xferlog_file=/var/log/vsftpd.log

Pam file, store as vsftpd.virtual

#%PAM-1.0
auth       required     pam_userdb.so db=/etc/vsftpd/vsftpd-virtual-user
account    required     pam_userdb.so db=/etc/vsftpd/vsftpd-virtual-user
session    required     pam_loginuid.so

And at last a file with user and password, which we will store as vusers.txt

ftpuser
letmein

All these files shall be stored into the same directory in order for build to be successful. We proceed building.

docker build -t centos-vsftpd -f  centos-vsftpd . 
Sending build context to Docker daemon  10.24kB
Step 1/10 : FROM centos:7
 ---> 1e1148e4cc2c
Step 2/10 : MAINTAINER xavi@xavignu.com
 ---> Using cache
 ---> cb00764989e4
Step 3/10 : RUN yum -y update; yum -y install which vsftpd net-tools vsftpd-sysvinit; yum clean all
 ---> Using cache
 ---> 84bc55dc256f
Step 4/10 : COPY vusers.txt /etc/vsftpd/
 ---> Using cache
 ---> 922453bc2ba3
Step 5/10 : RUN db_load -T -t hash -f /etc/vsftpd/vusers.txt /etc/vsftpd/vsftpd-virtual-user.db; rm -v /etc/vsftpd/vusers.txt; 	chmod 600 /etc/vsftpd/vsftpd-virtual-user.db
 ---> Using cache
 ---> 3f0f5a3743af
Step 6/10 : COPY vsftpd.conf /etc/vsftpd/
 ---> Using cache
 ---> f6241c5dc497
Step 7/10 : COPY vsftpd.virtual /etc/pam.d/
 ---> b768b27a3496
Removing intermediate container 45326ecc02a0
Step 8/10 : RUN mkdir -p /home/vftp/ftpuser; chown -R ftp:ftp /home/vftp
 ---> Running in fb940a0b999f
 ---> 8afff06f270a
Removing intermediate container fb940a0b999f
Step 9/10 : EXPOSE 20 21
 ---> Running in 0a9bd172c74e
 ---> d07e65112275
Removing intermediate container 0a9bd172c74e
Step 10/10 : CMD /usr/sbin/vsftpd -obackground=NO
 ---> Running in 50f124e366ee
 ---> 0a571ecf1fed
Removing intermediate container 50f124e366ee
Successfully built 0a571ecf1fed
Successfully tagged centos-vsftpd:latest

We now start the vsftpd container and check its running.

docker run -d --name myftp centos-vsftpd:latest; docker ps 
1034cc745e43f67ae3a432ce8ebe37755b36eca2dc04f21102da2eaafe9dd832
CONTAINER ID        IMAGE                  COMMAND                  CREATED                  STATUS                  PORTS               NAMES
1034cc745e43        centos-vsftpd:latest   "/usr/sbin/vsftpd ..."   Less than a second ago   Up Less than a second   20-21/tcp           myftp

We connect to newly created ftp server and upload a test file.

ftp 172.17.0.2 
Connected to 172.17.0.2.
220 (vsFTPd 3.0.2)
Name (172.17.0.2:xavi): ftpuser
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> mput test.txt
mput test.txt? y
200 PORT command successful. Consider using PASV.
150 Ok to send data.
226 Transfer complete.
10 bytes sent in 0.00 secs (187.8005 kB/s)
ftp> 

And we check the creation and content of the uploaded file.

docker exec myftp cat  /home/vftp/ftpuser/test.txt
Test File

References:

• Ubuntu vsftpd
• Docker documentation