Get a list of the possible FTP servers that are available in the Debian repositories?

Question

This may or may not be an extremely simple question that I am completely overlooking, but I have been working on assignment for my Networking Class. For this assignment, we are to open two Debian VMs (one being a clone of the other) that serve the places of a 'pc' and 'server'. In our 'server' VM we are to acquire a list of FTP servers currently available in the Debian Repositories(?).

While this question sounds simple, I have not been able to find a solution online, nor get help from the professor. It has not been taught to us either. It probably also helps that I am not that adept with Linux based machines.

Any help with this will be greatly appreciated!

What I currently know:

• The bolded question is word for the word the question assigned to us, so I am unable to clarify further what is being asked, which is why I am here (professor will not clarify either as he believes this is enough).
• This is not about programming, but rather using a FTP since the steps following deal with sharing a file between the two VMs via FTPs.
• The VMs we are currently using were set-up by the professor, so it could be possible there is a saved list of FTPs in the 'Debian Repository' but I am unsure how to access those.

This is also a repost as I was informed to repost it due to belonging it the wrong place, so in a previous discussion with Bodo it was noted the meaning of the question can be interpreted many different ways, which I understand. This question is quite vague and I do not understand it myself. It was also asked if this question had to deal with writing some kind of software, which it does not. Furthermore, it was also asked by Bodo if the question could be referring to FTPs currently reachable by the machine, which I do believe is possible. So this could be a route to explore. But I am unaware how to check this either.

Update

After some discussion with fellow students, I was informed to use 'sudo apt-cache search ftp | grep -i server'. This command displayed the following:

apt-cacher - Caching proxy server for Debian/Ubuntu software repositories

atftpd - advanced TFTP server

awffull - web server log analysis program

bzr-upload - Bazaar plugin for uploading to web servers

pawserv - CERNLIB data analysis suite - distributed PAW and file transfer servers

dnsmasq - Small caching DNS proxy and DHCP/TFTP server

dnsmasq-base - Small caching DNS proxy and DHCP/TFTP server

erlang-inets - Erlang/OTP Internet clients and servers

libghc-ftphs-dev - FTP Client and Server Library for Haskell

libghc-ftphs-doc - FTP Client and Server Library for Haskell; documentation

libghc-ftphs-prof - FTP Client and Server Library for Haskell; profiling libraries

ftpwatch - Notifies you of changes on remote ftp servers

gadmintools - GTK+ server administration tools (meta-package)

gatling - high performance web server and file server

gesftpserver - sftp server submodule for OpenSSH

globus-gridftp-server-dbg - Globus Toolkit - Globus GridFTP Server Debug Symbols

globus-gridftp-server-progs - Globus Toolkit - Globus GridFTP Server Programs

libglobus-gridftp-server-dbg - Globus Toolkit - Globus GridFTP Server Debug Symbols

libglobus-gridftp-server-dev - Globus Toolkit - Globus GridFTP Server Development Files

libglobus-gridftp-server6 - Globus Toolkit - Globus GridFTP Server

libglobus-gridftp-server-control-dbg - Globus Toolkit - Globus GridFTP Server Library Debug Symbols

libglobus-gridftp-server-control-dev - Globus Toolkit - Globus GridFTP Server Library Development Files

libglobus-gridftp-server-control0 - Globus Toolkit - Globus GridFTP Server Library

inetutils-ftpd - File Transfer Protocol server

libfax-hylafax-client-perl - simple Perl client for HylaFAX fax server

libnet-server-perl - extensible, general perl server engine

libnet-sftp-sftpserver-perl - Secure File Transfer Protocol Server

libnet-tftp-perl - Perl module for accessing TFTP servers

libnet-tftpd-perl - Perl extension for Trivial File Transfer Protocol Server

ftpd - File Transfer Protocol (FTP) server

ftpd-ssl - FTP server with SSL encryption support

mysecureshell - SFTP Server with ACL

tftpd - Trivial file transfer protocol server

nordugrid-arc-gridftpd - ARC GridFTP server

obex-data-server - D-Bus service for OBEX client and server side functionality

openssh-sftp-server - secure shell (SSH) sftp server module, for SFTP access from remote machines

pure-ftpd - Secure and efficient FTP server

pure-ftpd-common - Pure-FTPd FTP server (Common Files)

pure-ftpd-ldap - Secure and efficient FTP server with LDAP user authentication

pure-ftpd-mysql - Secure and efficient FTP server with MySQL user authentication

pure-ftpd-postgresql - Secure and efficient FTP server with PostgreSQL user >authentication

python-pyftpdlib - Python FTP server library

python3-pyftpdlib - Python FTP server library

sn - Small NNTP server for leaf sites

tftpd-hpa - HPA's tftp server

util-vserver - user-space tools for Linux-VServer virtual private servers

vsftpd - lightweight, efficient FTP server written for security

vsftpd-dbg - lightweight, efficient FTP server written for security (debug)

webfs - lightweight HTTP server for static content

publicfile-installer - installer package for the publicfile HTTP and FTP server

And seeing as a particular item is listed that is needed for a later step in the assignment (pure-ftpd), I believe this is the list I am looking for.

Answer 1

There is this question on Server Fault: How do I get a list of packages that “Provides” something" using dpkg?

One of the answers uses aptitude instead of dpkg (or apt, apt-cache or whatever). The point is the search feature of aptitude allows you to easily search by the "Provides" field. Any well-maintained FTP server package should report ftp-server in this field.

aptitude search '~Pftp-server'

Notes:

• You may need to install aptitude first.
• Don't forget to aptitude update (or equivalently apt-get update) before you search.
• The method works because there is a virtual package named ftp-server. See Debian Policy Manual, Declaring relationships between packages, Virtual packages - Provides.
• ftp-server means FTP, not SFTP nor TFTP. There is a virtual package named tftp-server, so in theory you can easily find these; but in practice it seems some TFTP server packages don't use the "Provides" field.
• Similarly it's possible some FTP server packages don't use the field and my command won't find them. Your approach with apt-cache search … | grep … may find them, but I can see it prints more than FTP servers; some heuristics and/or insight (with apt-cache show …) is needed to spot false positives. My command should not print false positives, everything it gives you should really be an FTP server. So my command may give you too few results but the results are firm; while your command gives you more results, but some of them should be discarded.