Trying to use TLS to connect to proftpd <1.3.5a can cause extensive delays during directory switches. Unstable Debian stretch (proftpd 1.3.5b-3) resolves this, though there is no backport to stable Debian jessie (proftpd 1.3.5-1.1+deb8u1), rendering proftpd useless for most users of stable secure servers. »After upgrading from Debian jessie»Debian stretch, which is now marked as the stable release, the issue has been resolved.

cd ~ mkdir proftpd cd proftpd # install Debian build tools: sudo apt-get install packaging-dev debian-keyring devscripts equivs # update Pretty Good Privacy (PGP) if needed: gpg -k # online check for existing package versions: rmadison proftpd-basic --architecture amd64 proftpd-basic | 1.3.3a-6squeeze7 | squeeze-security | amd64 proftpd-basic | 1.3.3a-6squeeze7 | squeeze | amd64 proftpd-basic | 1.3.4a-5+deb7u3 | wheezy-security | amd64 proftpd-basic | 1.3.4a-5+deb7u3 | wheezy | amd64 proftpd-basic | 1.3.5-1.1+deb8u1 | jessie-security | amd64 proftpd-basic | 1.3.5-1.1+deb8u1 | jessie | amd64 proftpd-basic | 1.3.5b-3 | stretch | amd64 proftpd-basic | 1.3.5b-3 | sid | amd64 # grab .dsc-file download location for old existing package and unpack it: lynx https://packages.debian.org/nl/stretch/proftpd-basic dget -x http://http.debian.net/debian/pool/main/p/proftpd-dfsg/proftpd-dfsg_1.3.5-1.1+deb8u1.dsc ls proftpd-dfsg-1.3.5/debian/ # grab .dsc-file download location for new wanted package and unpack it: lynx https://packages.debian.org/nl/stretch/proftpd-basic dget -x http://http.debian.net/debian/pool/main/p/proftpd-dfsg/proftpd-dfsg_1.3.5b-3.dsc ls proftpd-dfsg-1.3.5b/debian/ cd proftpd-dfsg-1.3.5b sudo mk-build-deps --install --remove dch --local ~bpo8+ --distribution jessie-backports "Rebuild for jessie-backports." cp ../proftpd-dfsg-1.3.5/debian/control debian/control #avoid dh_update_autotools_config cp ../proftpd-dfsg-1.3.5/debian/control.in debian/control.in #avoid dh_update_autotools_config cp ../proftpd-dfsg-1.3.5/debian/rules debian/rules #install -m 755 debian/proftpd-basic.init debian/proftpd-basic/etc/init.d/proftpd #install: cannot stat ‘debian/proftpd-basic.init’: No such file or directory cp debian/proftpd-basic.proftpd.init debian/proftpd-basic.init #install: cannot stat ‘debian/templates/default’: No such file or directory cp ../proftpd-dfsg-1.3.5/debian/templates/default debian/templates/default #error: no dependency information found for /usr/local/lib/libodbc.so.2 vi debian/rules #dh_shlibdeps -a --dpkg-shlibdeps-params=--ignore-missing-info #test build, by manually calling 'deb/rules': fakeroot debian/rules binary #dpkg-genchanges: error: cannot read ../proftpd-dfsg_1.3.5b-3~bpo8+1.dsc: No such file or directory cp ../proftpd-dfsg_1.3.5b-3.dsc ../proftpd-dfsg_1.3.5b-3~bpo8+1.dsc #real build, also implicitly calling 'deb/rules': dpkg-buildpackage -nc -us -uc -rfakeroot #nopreclean + nosigning + fake-root-privileges #make[3]: Entering directory '~/proftpd/proftpd-dfsg-1.3.5b/contrib/mod_load' #make[3]: *** No rule to make target 'clean'. Stop. #make[3]: Entering directory '~/proftpd/proftpd-dfsg-1.3.5b/contrib/mod_wrap2' #make[3]: *** No rule to make target 'clean'. Stop. #make[3]: Entering directory '~/proftpd/proftpd-dfsg-1.3.5b/contrib/mod_sftp' #make[3]: *** No rule to make target 'clean'. Stop. #make[2]: *** [clean] Error 2 #debian/rules:90: recipe for target 'myclean' failed sudo dpkg -i ../proftpd-basic_1.3.5b-3~bpo8+1_amd64.deb #Unpacking proftpd-basic (1.3.5b-3~bpo8+1) over (1.3.5-1.1+deb8u1) ... #220 ProFTPD 1.3.5 Server (...)»220 ProFTPD 1.3.5b Server (...)