Nmap Development mailing list archives
Re: ioctl issue scanning /24 networks
From: Daniel Miller <bonsaiviking () gmail com>
Date: Fri, 6 Jun 2014 07:09:11 -0500
Nicolas, Thanks for your bug report. On Fri, Jun 6, 2014 at 4:25 AM, Nicolas Greneche < 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 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. Thanks, Dan _______________________________________________ Sent through the dev mailing list http://nmap.org/mailman/listinfo/dev Archived at http://seclists.org/nmap-dev/
Current thread:
- ioctl issue scanning /24 networks Nicolas Greneche (Jun 06)
- Re: ioctl issue scanning /24 networks Daniel Miller (Jun 06)
- Re: ioctl issue scanning /24 networks Nicolas Greneche (Jun 06)
- Re: ioctl issue scanning /24 networks Jacek Wielemborek (Jun 06)
- Re: ioctl issue scanning /24 networks Nicolas Greneche (Jun 16)
- Re: ioctl issue scanning /24 networks Nicolas Greneche (Jun 06)
- Re: ioctl issue scanning /24 networks Daniel Miller (Jun 06)