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Bug#1007998: release-notes: netcat-openbsd incompatibilities



Package: release-notes
Severity: wishlist

Hi there,

netcat-openbsd 1.218-5 adds support for abstract sockets (on Linux),
which is a breaking change with possible security implications:
https://sources.debian.org/src/netcat-openbsd/1.218-5/debian/NEWS/ .
elbrus suggested to mention that in the Bookworm release notes; I
propose the following text, mostly straight from the NEWS entry — feel free to
adjust of course :-)

--8<--------------------------------------------------------------------->8--

netcat-openbsd and abstract socket support
==========================================

Starting with netcat-openbsd 1.218-5, nc.openbsd(1)'s Linux builds support
[abstract namespace sockets](https://manpages.debian.org/unix.7.en.html#Abstract_sockets)
in the AF_UNIX family.  Socket paths starting with an at symbol '@' are
interpreted in the abstract namespace.

This has possible security implications: `nc -lU @foobar.sock` used to bind
pathname socket '@foobar.sock' in the current directory, subject to umask and
file system access restrictions, while (on Linux) it now binds 'foobar.sock'
in the abstract namespace where ownership and permissions have *no meaning*.

In order to specify a pathname socket make sure the argument doesn't start
with '@'; for instance by prefixing with './' or by using a fully-qualified
socket path.  (Note however that on Linux socket pathnames may not exceed 108
bytes in size.)

This change is a Linux-only behavior, and only affects UNIX domain sockets
(flag '-U').

--8<--------------------------------------------------------------------->8--

Cheers
-- 
Guilhem.

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