Provided by: firehol-tools_3.1.7+ds-2_all bug


       vnetbuild - an easy to use but powerful namespace setup tool


       sudo vnetbuild CONFIGFILE { start | stop | status }

       vnetbuild CONFIGFILE graphviz OUTFILE.{gv|png|pdf|ps}


       VNetBuild  is a program that helps you set up groups of interconnected network namespaces,
       to simulate networks of  any  complexity  without  resorting  to  using  real  or  virtual

       This  is  ideal  for  testing  complex  multi-host configurations with a minimal amount of
       resources on a single machine:

       · Each namespace can have its own network setup, including firewall and QOS configuration.

       · Commands can be run in the namespace and will have that specific view  of  the  network,
         including running standard network tools and daemons.

       Run without any arguments, vnetbuild will present some help on usage.


       start  Sets up a series of network namespaces as defined in CONFIGFILE.  vnetbuild creates
              interconnected network devices as specified in the configuration, sets  up  routing
              and runs any custom commands that are given within the namespace.

       stop   Removes  any  devices  from  the  namespaces  defined  in  CONFIGFILE and kills any
              processes running with the namespaces, then removes the namespaces themselves.

       status For each namespace defined in CONFIGFILE, shows if it  is  active  and  if  so  its
              network devices and their configuration.

       graphviz OUTFILE
              Generates  a  graph  of the network defined in CONFIGFILE.  This does not need root
              access, nor does it require the namespaces to have been started.

              OUTFILE can be png pdf or ps.  If the  extension  gv  is  given  the  output  is  a
              graphviz(7) file which you can process separately.


       Once  you  have  created  a set of network namespaces, you can easily run any commands you
       want within them.  If for instance you defined  three  hosts  (host_a  with  IP,
       host_b with IP and host_c with IP connected via a common switch sw0:

               # ping host_b and host_c from host_a
               sudo ip netns exec host_a ping
               sudo ip netns exec host_a ping

               # use netcat to listen on host_a and send data from host_b
               # (use two terminals to run the commands simultaneously)
               sudo ip netns exec host_a nc -l -p 23
               sudo ip netns exec host_b nc -q 0 23 < /etc/hosts

               # capture traffic passing through the switch, then view it
               sudo ip netns exec sw0 tcpdump -i switch -w capfile
               wireshark capfile

               # Use 'firehol panic' in host_b to block all traffic
               # (you could equally load a full config etc.)
               sudo ip netns exec host_b firehol panic

               # this is now blocked
               sudo ip netns exec host_a ping

               # not blocked (host_b not involved)
               sudo ip netns exec host_a ping

               # obtain a shell for your regular user, only "in" host_c
               sudo ip netns exec host_c sudo -i -u $USER
               ip a | grep


       · vnetbuild.conf(5) - VNetBuild configuration file

       · firehol(1) - FireHOL program

       · fireqos(1) - FireQOS program

       · FireHOL Website (

       · VNetBuild Online PDF Manual (

       · VNetBuild Online Documentation (


       FireHOL Team.