Package: tigervnc-standalone-server Version: 1.7.0+dfsg-7 Severity: normal I am running a graphical IRC client in a VNC server. Previously I used realvnc, but since it got removed from Debian I switched to tigervnc around the start of the year. Since then I've noticed that after the VNC server has been running for a month or two, I can no longer get in on the first try. A second attempt is successful, until eventually it will require three attempts and so on. Eventually enough attempts are required that my client is blacklisted before I can successfully connect.
Some methodical testing revealed a way to reproduce the issue. Start a vnc server process: tigervncserver :10 -SecurityTypes None Then run a loop to start client processes: while :; do xvncviewer localhost:10 & sleep 1; done You can do a tail -f on the server log in another terminal if you wish. Soon enough you will start getting popups for "Too many security failures". The log will look something like this: Fri Aug 25 01:51:26 2017 Connections: accepted: 127.0.0.1::34667 Fri Aug 25 01:51:27 2017 Connections: accepted: 127.0.0.1::34668 Fri Aug 25 01:51:28 2017 Connections: accepted: 127.0.0.1::34669 SConnection: Client needs protocol version 3.8 SConnection: Client requests security type None(1) VNCSConnST: Server default pixel format depth 24 (32bpp) little-endian rgb888 Connections: closed: 127.0.0.1::34668 (Non-shared connection requested) EncodeManager: Framebuffer updates: 0 EncodeManager: Total: 0 rects, 0 pixels EncodeManager: 0 B (1:-nan ratio) Connections: closed: 127.0.0.1::34667 (Non-shared connection requested) EncodeManager: Framebuffer updates: 0 EncodeManager: Total: 0 rects, 0 pixels EncodeManager: 0 B (1:-nan ratio) Connections: closed: 127.0.0.1::34666 (Non-shared connection requested) EncodeManager: Framebuffer updates: 1 EncodeManager: Tight: EncodeManager: Solid: 1 rects, 2.28 Mpixels EncodeManager: 16 B (1:570001 ratio) EncodeManager: Total: 1 rects, 2.28 Mpixels EncodeManager: 16 B (1:570001 ratio) VNCSConnST: Client pixel format depth 24 (32bpp) little-endian rgb888 Note that no client information was printed for the two stub attempts. After a successful connection is made, the two stub connections are terminated, as well as the previous live connection. Using shared connections can be used to work around the problem. The failure mechanism seems to rely on connection "slots"; after a connection is forcibly terminated, its slot will become permanently unusable and the next connection to land in that slot will remain in a limbo indefinitely. However since a shared connection does not terminate other connections, the defunct slots remain filled with stub connections and each new connection gets a viable slot. I have not yet delved into the code, but based on this observation my theory is that there's an array of connections that gets reused, and new connections are incompletely initialized. A forced disconnection and subsequent new connection in the same array index would then land in a bad state where the server won't process it further. -- System Information: Debian Release: buster/sid APT prefers unstable APT policy: (500, 'unstable'), (500, 'testing'), (1, 'experimental') Architecture: amd64 (x86_64) Foreign Architectures: i386 Kernel: Linux 3.19.1-core2 (SMP w/8 CPU cores) Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8), LANGUAGE=en_US.utf8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Init: sysvinit (via /sbin/init) Versions of packages tigervnc-standalone-server depends on: ii libaudit1 1:2.7.7-1+b2 ii libbsd0 0.8.6-1 ii libc6 2.24-14 ii libgcc1 1:7.2.0-1 ii libgcrypt20 1.7.8-2 ii libgl1-mesa-glx [libgl1] 13.0.6-1+b2 ii libgnutls30 3.5.13-2 ii libjpeg62-turbo 1:1.5.1-2 ii libpam0g 1.1.8-3.6 ii libpixman-1-0 0.34.0-1 ii libselinux1 2.6-3+b2 ii libstdc++6 7.2.0-1 ii libsystemd0 232-25 ii libx11-6 2:1.6.4-3 ii libxau6 1:1.0.8-1+b2 ii libxdmcp6 1:1.1.2-3 ii libxfont2 1:2.0.1-3 ii libxshmfence1 1.2-1+b2 ii perl 5.26.0-5 ii x11-xkb-utils 7.7+3+b1 ii xauth 1:1.0.9-1+b2 ii xkb-data 2.19-1.1 ii zlib1g 1:1.2.8.dfsg-5 Versions of packages tigervnc-standalone-server recommends: pn libgl1-mesa-dri <none> ii tigervnc-common 1.7.0+dfsg-7 ii x11-xserver-utils 7.7+7+b1 ii xfonts-base 1:1.0.4+nmu1 Versions of packages tigervnc-standalone-server suggests: ii xfonts-75dpi 1:1.0.4+nmu1 pn xfonts-scalable <none> -- no debconf information
