[Pkg-utopia-maintainers] Bug#761850: dhclient problem caused by disconnected stderr socket

[Michael Biebl]

Control: tags -1 + moreinfo

Hi

On Sat, 04 Oct 2014 13:58:40 -0400 Michael Paul <mike at wyzardry.net> wrote:
> I've encountered this too, and it looks like it's not a problem with 
> dhclient itself.  It may not be NetworkManager either.  I suspect 
> systemd, but I'm not sure.
> 
> Investigating with strace, I found that dhclient is terminating due to a 
> SIGPIPE when trying to write its first line of output ("Internet Systems 
> Consortium DHCP Client") to stderr.  Its /proc/self/fd shows that stderr 
> is a socket:  the "2" link points to "socket:[15055]".  I thought the 
> socket might be connected to NetworkManager, so I checked and found that 
> actually NetworkManager's stderr is the same socket; both processes are 
> sending their output to the same place.
> 
> However, it's not clear what the socket actually connects to. Figuring 
> the number 15055 was an inode number of a Unix domain socket file, I ran 
> "find / -inum 15055" as root, but didn't find anything.  I also did "ls 
> -l /proc/*/fd/* | grep 15055", and the only hits were the stdout and 
> stderr of the NetworkManager process.
> 
> After restarting NetworkManager, its stderr was a *different* socket 
> (different number), and dhclient inherited that new socket and was able 
> to run successfully.  But I did another search and couldn't find any 
> socket files with the new inode number, nor any hits in /proc/*/fd 
> besides the new NetworkManager and dhclient processes, so it's still 
> unclear what's on the other end of the socket even when it's working.
> 
> I suspect systemd is involved since NetworkManager had the bad socket as 
> its stderr, and stderr is typically provided by the parent process, and 
> NetworkManager is started by systemd.  But without knowing what the 
> socket connects to, it's hard to be sure.

Can you still reproduce this issue with an up-to-date stretch system?



-- 
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universe are pointed away from Earth?

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