Re: ioctl issue scanning /24 networks

[Nicolas Greneche <nicolas.greneche () univ-paris13 fr>]

Le 06/06/2014 14:09, Daniel Miller a écrit :
> Nicolas,
>
> Thanks for your bug report.
>
> On Fri, Jun 6, 2014 at 4:25 AM, Nicolas Greneche
> <nicolas.greneche () univ-paris13 fr
> <mailto:nicolas.greneche () univ-paris13 fr>> wrote:
>
>
>     epoll_wait(4, {}, 128, 50)              = 0
>     ioctl(3, TIOCGPGRP, [0])                = -1 ENOTTY (Inappropriate
>     ioctl for device)
>     epoll_wait(4, {}, 128, 50)              = 0
>     ioctl(3, TIOCGPGRP, [0])                = -1 ENOTTY (Inappropriate
>     ioctl for device)
>     epoll_wait(4, {}, 128, 50)              = 0
>     ioctl(3, TIOCGPGRP, [0])                = -1 ENOTTY (Inappropriate
>     ioctl for device)
>
>     Those messages loop forever. Nmap process never exit.
>
>
> I'm not sure what's the core issue here, but I did look into the ioctl
> calls, and they seem to be coming from tty_getchar in nmap_tty.cc. The
> call to tcgetpgrp on fd 3 results in ENOTTY, which is ok because
> obviously the process forked by python-nmap is not running in a TTY (a
> rare case of ENOTTY actually meaning what it says!). We could try to
> avoid polling like this when we can detect this situation, but as the
> comment in the function states:
>
>          // This is so that when the terminal has been disconnected, it
> will be
>          // reconnected when possible. If it slows things down, just
> remove it

That's it, i run my program from a screen session.

> I think this covers the scenario of running Nmap in a GNU Screen
> session, for instance, and then disconnecting the session. The process's
> output is no longer a TTY, but when you reconnect, you will regain the
> ability to send keyboard interaction messages.
>
> Sorry for the long-winded explanation of part of your strace output, but
> I wanted to make sure for myself that a recent change to our keyboard
> interaction code was not responsible for your problem. It looks instead
> like a Nsock issue, based on the epoll_wait calls.
>
> If you can reliably cause the hang (especially if you can do it without
> using python-nmap, but by running the command directly), please let us
> know if it still hangs with "--nsock-engine select" and provide some
> Nmap debugging output "-d" as well.

I can make a shell script that loop on the network blocks and call nmap 
command for each block ?

Does "--nsock-engine select" stands for a compilation option (but I 
didn't see it in ./configure --help) or an argument tu nmap command (not 
seen in nmap -h) ?

> Thanks,
> Dan


--
Nicolas Grenèche

URL : http://blog.etcshadow.fr
Tel : 01 49 40 40 35
Fax : 01 48 22 81 50
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