Category Archives: Qubes OS

I’ve started recently to use Qubes OS and I want to set up a virtual IDS and IPS in separate VMs, but I can’t figuring out how the comunications between different VMs works here.

Each VM should be isolated and all the connections handled by a separate FirewallWM (sys-firewall), which is connected to the NetWM (sys-net), which, in the basic configuration, is the only one which has Network Device attached (Ethernet and WiFi cards).

I’ve read the iptables in all VMs and I found the VM Manager set up automatically a DNAT Redirection to let the DNS packets (port 53) exit thought sys-net, but I can’t understand how all the packets can go through each layer and return back to the different original sources AppVM connected through sys-firewall.

For what concerns the IDS and IPS, I can easily handle and filter packet base on the content, but I can’t think how to fiter, for example, Source IP based on a blacklist, since I can’t see the real origin and since each VM is a separate system which can be based on differents Template (Fedora, Debian, Whonix, …) I think the Packet Options can be altered.

So, the iptables and the auditings like Psad can only be placed in the VM that is directly connected to the Router?

Some basic infos

• Qubes OS is a system based on Isolation through Hardware Virtualization Technology that let you run different Domains (Personal, Work, Untrusted, … ) based on different Systems (Templates) on VMs and each instance is complete separate from others, so that if one get compromised, the system remains clean and fully usable
• You can choose what devices attach to a VM and detach from it, so in the standard and savy configuration you have a sys-net machine wich is the only one that can connect to Internet (Ethernet/WiFi attached) and a sys-firewall machine which handle all the connections and pass through sys-net, so you have 2 level (you can add more) of isolation for the other domains (ex. PublicWiFi -> sys-firewall -> sys-net, Trusted -> sys-firewall -> sys-net )

I’ll post the sys-firewall and sys-net ifconfig and iptables-save outputs, to give you all the details.

VMs Details:

             me | updbl |  type |         netvm |          ip |    ip back | gateway/DNS |
----------------+-------+-------+---------------+-------------+------------+-------------+
         {dom0} |   Yes | Admin |           n/a |  10.137.0.2 | 10.137.0.1 |         n/a |
      {sys-net} |       |   Net |           n/a |        None | 10.137.1.1 |         n/a |
 {sys-firewall} |       | Proxy |       sys-net |  10.137.1.8 | 10.137.2.1 |  10.137.1.1 |
   {sys-whonix} |       | Proxy |  sys-firewall | 10.137.2.10 | 10.137.3.1 |  10.137.2.1 |
      {sys-usb} |       |   Net |           n/a |        None | 10.137.4.1 |         n/a |
    [fedora-23] |   Yes |   Tpl | *sys-firewall |  10.137.2.3 |        n/a |  10.137.2.1 |
      untrusted |       |       | *sys-firewall |  10.137.2.9 |        n/a |  10.137.2.1 |
     [debian-8] |   Yes |   Tpl |  sys-firewall |  10.137.2.4 |        n/a |  10.137.2.1 |
       personal |       |       |             - |        None |        n/a |         n/a |
    [whonix-gw] |   Yes |   Tpl |    sys-whonix |  10.137.3.5 |        n/a |  10.137.3.1 |
    [whonix-ws] |   Yes |   Tpl |    sys-whonix |  10.137.3.6 |        n/a |  10.137.3.1 |
    anon-whonix |       |       |    sys-whonix | 10.137.3.11 |        n/a |  10.137.3.1 |

sys-firewall iptables:

*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]

:PR-QBS - [0:0]
:PR-QBS-SERVICES - [0:0]

-A PREROUTING -j PR-QBS
-A PREROUTING -j PR-QBS-SERVICES

-A POSTROUTING -o vif+ -j ACCEPT
-A POSTROUTING -o lo -j ACCEPT
-A POSTROUTING -j MASQUERADE

-A PR-QBS -d 10.137.2.1/32 -p udp -m udp --dport 53 -j DNAT --to-destination 10.137.1.1
-A PR-QBS -d 10.137.2.1/32 -p tcp -m tcp --dport 53 -j DNAT --to-destination 10.137.1.1

-A PR-QBS -d 10.137.2.254/32 -p udp -m udp --dport 53 -j DNAT --to-destination 10.137.1.254
-A PR-QBS -d 10.137.2.254/32 -p tcp -m tcp --dport 53 -j DNAT --to-destination 10.137.1.254

sys-firewall ifconfig:

eth0      Link encap:Ethernet  HWaddr 00:16:3e:5e:6c:06  
          inet addr:10.137.1.8  Bcast:10.255.255.255  Mask:255.255.255.255
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:N errors:0 dropped:0 overruns:0 frame:0
          TX packets:N errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:N errors:0 dropped:0 overruns:0 frame:0
          TX packets:N errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 

sys-net iptables:

COMMIT

*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]

:PR-QBS - [0:0]
:PR-QBS-SERVICES - [0:0]

-A PREROUTING -j PR-QBS
-A PREROUTING -j PR-QBS-SERVICES

-A POSTROUTING -o vif+ -j ACCEPT
-A POSTROUTING -o lo -j ACCEPT
-A POSTROUTING -j MASQUERADE

-A PR-QBS -d 10.137.1.1/32 -p udp -m udp --dport 53 -j DNAT --to-destination 192.168.1.1
-A PR-QBS -d 10.137.1.1/32 -p tcp -m tcp --dport 53 -j DNAT --to-destination 192.168.1.1

-A PR-QBS-SERVICES -d 10.137.255.254/32 -i vif+ -p tcp -m tcp --dport 8082 -j REDIRECT

sys-net ifconfig:

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        loop  txqueuelen 1  (Local Loopback)
        RX packets N bytes N
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets N bytes N
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

vif62.0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.137.1.1  netmask 255.255.255.255  broadcast 0.0.0.0
        ether fe:ff:ff:ff:ff:ff  txqueuelen 32  (Ethernet)
        RX packets N bytes N
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets N bytes N
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlp0s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.4  netmask 255.255.255.0  broadcast 192.168.1.255
        ether 30:3a:64:3a:a2:2d  txqueuelen 1000  (Ethernet)
        RX packets N bytes N
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets N bytes N
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

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