sudo yum update fedup fedora-release sudo fedup --network 21 --product=workstationDownloading packages, reboot, upgrade and everything worked fine. I went to second step.
sudo fedup --network 22Downloading packages one more time, reboot and upgrade. Just to clean up that RPMs mess and that's all
sudo rpm --rebuilddb sudo yum distro-sync --setopt=deltarpm=0...and I got this
Yum command has been deprecated, use dnf instead. See 'man dnf' and 'man yum2dnf' for more information. To transfer transaction metadata from yum to DNF, run 'dnf migrate' Redirecting to '/usr/bin/dnf distro-sync --setopt=deltarpm=0
alias yum=`dnf`and that's all. DNF has the same set of command line parameters so you can safely use your DNF-under-the-hood tool. Ok, let's get back to cleaning up packages puddle.
sudo dnf distro-sync --setopt=deltarpm=0 sudo dnf install rpmconf sudo rpmconf -aUpgrade finished. Everything worked fine, at least for the time when I tried to connect to the network at work through VPN. NetworkManager after about half a minute displayed gentle message with short opinion about my VPN keys and suggestion where can I put them. I checked the logs
$ journalctl -f -u NetworkManager Mon Jul 14 16:24:18 2015 us=55541 OpenVPN 2.2.2 x86_64-unknown-linux-gnu [SSL] [LZO2] [EPOLL] [PKCS11] [eurephia] built on Jul 14 2015 ------- SNIP ------- Mon Jul 14 16:24:23 2015 us=212915 TLS: tls_multi_process: i=0 state=S_SENT_KEY, mysid=959d12ad 3fd6358b, stored-sid=21b1e50a 63e80c5c, stored-ip=184.108.40.206:1194 Mon Jul 14 16:24:23 2015 us=212920 TLS: tls_process: chg=0 ks=S_SENT_KEY lame=S_UNXXF to_link->len=0 wakeup=604800 Mon Jul 14 16:24:23 2015 us=212925 ACK reliable_can_send active=0 current=0 :  Mon Jul 14 16:24:23 2015 us=212931 BIO write tls_write_ciphertext 100 bytes Mon Jul 14 16:24:23 2015 us=212935 Incoming Ciphertext -> TLS Mon Jul 14 16:24:23 2015 us=213196 VERIFY OK: depth=1, /C=XX/ST=MYTOWN/L=MYTOWN/O=OpenVPN-Myprovider/CN=OpenVPN-Myprovider-CA/emailAddressemail@example.com Mon Jul 14 16:24:23 2015 us=213223 VERIFY ERROR: depth=0, error=certificate signature failure: /C=XX/ST=MYTOWN/O=OpenVPN-Myprovider/CN=server/emailAddressfirstname.lastname@example.org Mon Jul 14 16:24:23 2015 us=213238 SSL alert (write): fatal: decrypt error Mon Jul 14 16:24:23 2015 us=213271 TLS_ERROR: BIO read tls_read_plaintext error: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed Mon Jul 14 16:24:23 2015 us=213277 TLS Error: TLS object -> incoming plaintext read error Mon Jul 14 16:24:23 2015 us=213282 TLS Error: TLS handshake failedAfter not-so-short digging through the Internet I found an information that verification using MD5 was disabled because it's not secure enough anymore. Information is important, but I need an answer how to fix that. After further searching/reading/cursing I have found the solution for the problem. I needed a silver bowl, ritual knife and blood of... uhmmm, not this... I needed to open one file (/usr/lib/systemd/system/NetworkManager.service) and add a line that enables MD5 verification.
sudo vim /usr/lib/systemd/system/NetworkManager.serviceService section should contain line like this
[Service] Environment="OPENSSL_ENABLE_MD5_VERIFY=1 NSS_HASH_ALG_SUPPORT=+MD5"Save file with [Esc] and :x and restart NetworkManager service
systemctl daemon-reload systemctl restart NetworkManager.serviceAfter that changes VPN is working like a charm (apart from the fact that is uses lame MD5 for verificatrion). Uptade: It seems that I made a mistake by making a statement that DNF has the same coomand line interface as Yum. There are several differences those package managers. List of changes can be found at DNF documentation web page.