Install Additional Software Safely
Installing additional Software on Whonix ™. Safety considerations.
Whonix ™ users are free to install their favorite software packages, but should be aware that additional software increases the attack surface of the platform. Since Whonix ™ is a Debian derivative, new users should always follow Debian advice when installing or removing packages to avoid common mistakes which can break or destabilize the system.
Almost any application can be installed, with a few exceptions for programs that are impossible to torify. In addition, Whonix ™ provides:
- protection from IP and DNS leaks (see above for details)
- partial protection against protocol leaks and fingerprinting, but this is far from perfect
Users are responsible for trying to prevent any other protocol leaks using the "Torify: How-to" guide, but most of those are mitigated by Whonix ™.
- Read the protocol leak and fingerprinting protection entry first. It highlights useful information, like the fact that DNS and IP-related leaks do not apply to Whonix ™.
- Refer to the Tor Project's Torify: How-to which discusses various protocol leaks and how to mitigate them.
- Review the Tor Project's Transparent Proxy Leaks documentation, which is particularly relevant for users other custom workstations using Microsoft Windows.
Whonix-Workstation ™ is Firewalled
The Whonix-Gateway ™ firewall  has several effects upon Whonix-Workstation ™.
Table: Whonix-Gateway ™ Firewall Effects
|Additional Firewall Restrictions||The firewall on Whonix-Gateway ™ is very restrictive. It can be made even more restrictive by activating options within the firewall script.  It is possible to limit which outgoing ports are redirected to Tor's |
|DNS Requests||Standard DNS requests on UDP port |
|IPv6||Tor only partially supports IPv6, although full implementation is likely in the near term.  This is not a Whonix ™-specific issue. |
|Server Services||Onion Services and/or Location Hidden Services can be hosted.|
|Tor Routing||All traffic originating from Whonix-Workstation ™ and Whonix-Gateway ™ is routed over Tor.        Refer to the footnotes for further information.|
|UDP||Tor does not support UDP. This is not a Whonix ™-specific issue.|
Install Software General
- ↑ The firewall is found on Whonix-Gateway ™: /usr/bin/whonix_firewall
## Optionally restrict TransPort. ## Replace above rule with a more restrictive one, e.g.: #$iptables_cmd -t nat -A PREROUTING -i "$int_if_item" -p tcp --match multiport --dports 80,443 --syn -j REDIRECT --to-ports "$TRANS_PORT_WORKSTATION"
- ↑ If the DNS server is changed in Whonix-Workstation ™ /etc/resolv.conf, this will likely have no effect. The reason is the firewall on Whonix-Gateway ™ will redirect all those requests to Tor's
DnsPort. The working exception to this rule is when users tunnel / encrypt DNS requests (DNSCrypt, httpsdnsd), as per the secondary DNS resolver instructions.
- ↑ The only missing elements at the time of writing were automatic client connections and inter-relay connections via IPv6. Bridges are fully supported. See also: IPv6 roadmap.
- ↑ https://phabricator.whonix.org/T509
Since Whonix ™ version
0.2.1Whonix-Gateway ™ traffic is also routed over Tor. In this way, use of Whonix ™ is hidden from persons or systems observing the network.
- ↑ To preserve the anonymity of a user's Whonix-Workstation ™ activities, it is not necessary to torify Whonix-Gateway ™ own traffic.
For reader interest: If DNS settings on Whonix-Gateway ™ are changed in
/etc/resolv.conf, this only affects Whonix-Gateway ™ own DNS requests issued by applications using the system's default DNS resolver. By default, no applications issuing network traffic on Whonix-Gateway ™ use the system's default DNS resolver. All applications installed by default on Whonix-Gateway ™ that issue network traffic (apt, systemcheck, sdwdate) are explicitly configured, or forced by uwt wrappers, to use their own Tor
SocksPort(see Stream Isolation).
Whonix-Workstation ™ default applications are configured to use separate Tor
SocksPorts(see Stream Isolation), thereby not using the system's default DNS resolver. Any applications in Whonix-Workstation ™ that are not configured for stream isolation - for example
nslookup- will use the default DNS server configured in Whonix-Workstation ™ (via
/etc/network/interfaces), which is the Whonix-Gateway ™. Those DNS requests are redirected to Tor's DnsPort by Whonix-Gateway ™ firewall. Whonix-Gateway ™
/etc/resolv.confdoes not affect Whonix-Workstation ™ DNS requests.
Traffic generated by the Tor process itself which runs by Debian default under user
debian-tororiginating from Whonix-Gateway ™ can use the internet normally. This is because user
debian-toris exempted in Whonix-Gateway ™ Firewall, allowed to use the "normal" internet.
The Tor software (as of
0.4.5.6) (and no changed were announced at time of writing) almost exclusively uses TCP traffic. See also Tor wiki page, chapter UDP. For DNS, see next footnote.
Tor does not require, use functional (system) DNS for most functionality. IP addresses of Tor directory authorities are hardcoded in the Tor software as per Tor upstream default. Exceptions include:
- proxy settings using proxies with host names rather than IP addresses
- the Tor pluggable transport meek lite to resolve domains used in setting
front=to IP addresses.
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