After around 2 and half years of continues development, the Debian team has finally marked the Stretch release as stable. Releasing it as the current Debian operating system.
Debian 9 Stretch was announced as the upcoming development release in November, 2014. As of 17 June, 2017, the distribution was released.
The following changes were most noticeable:
Debian 9 Stretch is shipping with Linux kernel 4.9, GNOME 3.22, KDE 5.8, MATE 1.16 Xfce 4.12, LibreOffice 5.2, GCC 6.3, Python 3.5 and PHP 7. nftables firewall is now ready to replace iptables by default. Which is explained in details in Debian’s blog.
MySQL packages were all replaced by MariaDB packages by default.
Additionally, the following packages were updated:apt is the default package manager in Debian. In Stretch, it received a number of improvements. Such as rejecting weak checksums algorithms (like SHA1).
The famous warning message “hash sum mismatch” is finally going to be removed. However, if you are using 3rd party repositories, they have to adapt the by -hash layout in their repositories in order to fix such message. More about it is here.
Debian 9 is the first release of Debian to use the modern branch of GnuPG by default. It no longer depends on GnuPG 1.1 or GnuPG 2.0 (but they are available if you want them from repositories). Which adds “elliptic curve cryptography, better defaults, a more modular architecture, and improved smartcard suppor” according to Debian.
Debian 9 Stretch is the first Debian version to not require root privileges when running the Xorg display server. This is important in order to limit the possibility of privilege escalation in Xorg. However, you need to have some requirements to do so, such as installing logind and libpam-systemd, supporting KMS and using GDM 3 (only GDM 3 supports running it without root privileges).
If Xorg was started with a normal user privileges, the default log file will now be in ~/.local/share/xorg/.dmesg command now requires root privileges to be used. A new mirror for Debian was set up on deb.debian.org. PowerPC architecture support was dropped. All new binaries built with GCC 6 will be compiled as PIE (position independent executables).
You can download Debian 9 for i686, x86_64, ARM, Mips and a lot of other architectures for free from the Debian website. Many installation medias are available. Such as CD, DVD and Net Install.
For complete changelog, check the Debian 9 release notes.