From a SunOS client, I telnetted to port 53 of a host running BIND-4.9.5-P1.
 Once the connection was open, entered "foobar", hit return, then closed
 the telnet connection (control-rightbracket 'quit').

 The symptoms you see on the server is that named will no longer accept any
 TCP connections (zone transfers from the server fail, as well as simple
 TCP-based queries).  The named process may also consume lots of CPU now,
 affecting the rest of the system.

 Tracing the named process shows that when it receives this bogus message, it
 tries (and keeps trying) to read and write this socket, first resulting in
 a ECONNRESET, and then result in repeated EPIPE.  It appears to be in a pretty
 tight loop, presumably accounting for the system-wide impact.

 BIND-4.9.3-P1 doesn't have this problem.  It just closed the socket and went
 back to the main polling loop.


 I tested on the following platform:
  Sun SPARCstation 5 running SunOS 4.1.4
  BIND-4.9.5-P1
  Default options.h file
  Default Makefile, with the standard sunos4.1.x section in the Makefile
   uncommented, using /usr/bin/cc, and not building the shared library version

   of libresolv.
 (Also tested on Solaris 2.5.1 with gcc.)