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Asked: 2013-03-07 15:08:24 +0800 CST

Identify when a TCP socket is opened with inotify

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As the title suggests, is there a way of being notified of recently opened sockets using inotify/inotify-tools? As far as I can tell inotify only works with inodes and specifically testing if those inodes are sockets isn't something that inotify is actually capable of. Further to that, I can't seem to find where sockets FD's are stored. I can only see their file descriptors which are symlinks:

# ls -l /proc/29711/fd/10 
lrwx------ 1 root root 64 Mar  6 17:04 /proc/29711/fd/10 -> socket:[750728]

# stat /proc/29711/fd/10
  File: `/proc/29711/fd/10' -> `socket:[750728]'
  Size: 64              Blocks: 0          IO Block: 1024   symbolic link
Device: 3h/3d   Inode: 759700      Links: 1
Access: (0700/lrwx------)  Uid: ( 0/    root)   Gid: ( 0/    root)
Access: 2013-03-06 17:05:22.690411801 +1100
Modify: 2013-03-06 17:04:14.062414880 +1100
Change: 2013-03-06 17:04:14.062414880 +1100
 Birth: -
inotify

2 Answers

  1. Best Answer

    Inotify is for filesystem events monitoring, so unless there is special FS representing system's sockets — no way.

    I recommend looking at netlink and at its NETLINK_INET_DIAG in particular, but I can't tell for sure whether it has corresponding facilities at all.

    UPDATE: I've shared this question-answer and Pavel Emelyanov — CRIU's primarily developer, confirmed my suspicions — more than likely you can't get those notifications with netlink.

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  2. Update: you can track these events with conntrack-tools.

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