[erlang-questions] low level packet access from erlang

Garry Hodgson <>
Tue Jun 4 15:08:49 CEST 2013


On 04/03/2013 05:24 PM, Michael Santos wrote:
>
> I wrote an Erlang tun/tap interface on top of procket:
>
> https://github.com/msantos/tunctl
i've been playing with tunctl, but can't seem to get
it past initial eperm problems in create(). i'm guessing
i missed some kind of setup step, but i don't know what.

i set the capabilities as per instructions:

--> getcap /usr/local/lib/erlang/erts-5.9.2/bin/beam.smp 
/usr/local/lib/erlang/erts-5.9.2/bin/beam
/usr/local/lib/erlang/erts-5.9.2/bin/beam.smp = cap_net_admin+ep
/usr/local/lib/erlang/erts-5.9.2/bin/beam = cap_net_admin+ep

running as root, when i try tuncer:create() with or without args, i get:

()2> tuncer:create( <<"tun0">> ).
** exception exit: {badmatch,{error,eperm}}
      in function  tuncer:init/1
      in call from gen_server:init_it/6 (gen_server.erl, line 304)
      in call from proc_lib:init_p_do_apply/3 (proc_lib.erl, line 227)
()3>
=CRASH REPORT==== 4-Jun-2013::08:28:13 ===
   crasher:
     initial call: tuncer:init/1
     pid: <0.64.0>
     registered_name: []
     exception exit: {{badmatch,{error,eperm}},
                      [{tuncer,init,1,[]},
                       {gen_server,init_it,6,

any idea what i may be missing?

-- 
Garry Hodgson
AT&T Chief Security Office (CSO)

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