Install Additional Software Safely
Installing additional Software on Whonix. Safety considerations.
Whonix users are free to install their favorite software packages.
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
- 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.
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.
The user should be aware that additional software increases the attack surface of the platform.
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.
Starting from Whonix version
0.2.1, traffic from Whonix-Gateway is also routed over Tor. This approach conceals the use of Whonix from entities monitoring the network.
- For preserving the anonymity of a user's Whonix-Workstation activities, it isn't essential to route Whonix-Gateway's own traffic through Tor.
For those interested: Altering DNS settings on Whonix-Gateway in
/etc/resolv.confonly impacts DNS requests made by Whonix-Gateway's applications that utilize the system's default DNS resolver. By default, no applications on Whonix-Gateway that generate network traffic utilize this default resolver. All default applications on Whonix-Gateway that produce network traffic (like apt, systemcheck, sdwdate) are explicitly configured, or force by uwt wrappers, to use their dedicated Tor
SocksPort(refer to Stream Isolation).
Whonix-Workstation's default applications are configured to use dedicated Tor
SocksPorts(see Stream Isolation), avoiding the system's default DNS resolver. Any applications in Whonix-Workstation not set up for stream isolation - such as
nslookup- will employ the default DNS server configured in Whonix-Workstation (through
/etc/network/interfaces), which points to Whonix-Gateway. These DNS requests are then redirected to Tor's DnsPort by the Whonix-Gateway firewall. Changes in Whonix-Gateway's
/etc/resolv.confdon't influence Whonix-Workstation's DNS queries.
Traffic produced by the Tor process, which by Debian's default operates under the user
debian-tororiginating from Whonix-Gateway, can access the internet directly. This is permitted because Linux user account
debian-toris exempted in the Whonix-Gateway Firewall and allowed to use the "regular" internet.
0.4.5.6(with no changes announced at the time of writing), the Tor software predominantly relies on TCP traffic. For further details, see Tor wiki page, chapter UDP. For DNS, please refer to the next footnote.
Tor doesn't depend on, nor uses a functional (system) DNS for most of its operations. IP addresses of Tor directory authorities are hardcoded in the Tor software by Tor developers. Exceptions are:
- Proxy settings that use proxies with domain names instead of IP addresses.
- Some Tor pluggable transports such as meek lite, which resolves domains set in
front=to IP addresses or snowflake's