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- deactivates previews in Nautilus
- deactivates TCP timestamps
- deactivates Netfilter's connection tracking helper
.
Changes to the file browser only take effect for newly created user accounts. Not for
existing user accounts. This package is most useful to help Linux distribution
maintainers setting divergent defaults.
.
TCP time stamps (rfc 1323) allow for tracking clock
information with millisecond resolution. This may or may not allow an
attacker to learn information about the system clock at such
a resolution, depending on various issues such as network lag.
This information is available to anyone who monitors the network
somewhere between the attacked system and the destination server.
It may allow an attacker to find out how long a given
system has been running, and to distinguish several
systems running behind NAT and using the same IP address. It might
also allow to look for clocks that match an expected value to find the
public IP used by a user.
.
Hence, this package disables this feature by shipping the
/etc/sysctl.d/tcp_timestamps.conf configuration file.
.
Note that TCP time stamps normally have some usefulness. They are
needed for:
.
* the TCP protection against wrapped sequence numbers; however, to
trigger a wrap, one needs to send roughly 2^32 packets in one
minute: as said in rfc 1700, "The current recommended default
time to live (TTL) for the Internet Protocol (IP) [45,105] is 64".
So, this probably won't be a practical problem in the context
of Anonymity Distributions.
.
* "Round-Trip Time Measurement", which is only useful when the user
manages to saturate their connection. When using Anonymity Distributions,
probably the limiting factor for transmission speed is rarely the capacity
of the user connection.
.
Netfilter's connection tracking helper module increases kernel attack
surface by enabling superfluous functionality such as IRC parsing in
the kernel (!)
.
Hence, this package disables this feature by shipping the
/etc/sysctl.d/nf_conntrack_helper.conf configuration file.
(This package description has been [automatically](https://github.com/Whonix/whonix-developer-meta-files/blob/master/debug-steps/packaging-helper-script) extracted and mirrored from `debian/control`.)