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sshd goes catatonic on AIX 5.2 ML1 - AIX

On our AIX 5.2 ML1 installation, sshd stops accepting connections after a few minutes. This does not happen on our other AIX 5.2 machine without ML1. Versions: openssh 3.6.1.5200 zlib 1.1.4-2 (RPM) openssl 0.9.6g-3 (RPM) bos.rte.libc 5.2.0.10 Plain AIX 5.2 (no ML1) has libc 5.2.0.0 - but we didn't want to play around with libc too much. We did copy the 5.2.0.0 libc into /opt/freeware/lib (first in the search path for sshd), but that didn't work. dump -Hv indicates that sshd doesn't use any libraries besides libc, libcrypto and libz. Has anybody seen this behaviour? Cheers, Florian...

  1. #1

    Default sshd goes catatonic on AIX 5.2 ML1


    On our AIX 5.2 ML1 installation, sshd stops accepting connections
    after a few minutes. This does not happen on our other AIX 5.2 machine
    without ML1.

    Versions:

    openssh 3.6.1.5200
    zlib 1.1.4-2 (RPM)
    openssl 0.9.6g-3 (RPM)
    bos.rte.libc 5.2.0.10

    Plain AIX 5.2 (no ML1) has libc 5.2.0.0 - but we didn't want to play
    around with libc too much. We did copy the 5.2.0.0 libc into
    /opt/freeware/lib (first in the search path for sshd), but that didn't
    work.

    dump -Hv indicates that sshd doesn't use any libraries besides libc,
    libcrypto and libz.

    Has anybody seen this behaviour?

    Cheers,
    Florian

    Florian M. Weps Guest

  2. #2

    Default Re: sshd goes catatonic on AIX 5.2 ML1

    Florian M. Weps <fwepsgreenmail.ch> wrote:

    FMW> On our AIX 5.2 ML1 installation, sshd stops accepting connections
    FMW> after a few minutes. This does not happen on our other AIX 5.2 machine
    FMW> without ML1.

    FMW> Versions:

    FMW> openssh 3.6.1.5200
    FMW> zlib 1.1.4-2 (RPM)
    FMW> openssl 0.9.6g-3 (RPM)
    FMW> bos.rte.libc 5.2.0.10

    FMW> Plain AIX 5.2 (no ML1) has libc 5.2.0.0 - but we didn't want to play
    FMW> around with libc too much. We did copy the 5.2.0.0 libc into
    FMW> /opt/freeware/lib (first in the search path for sshd), but that didn't
    FMW> work.

    FMW> dump -Hv indicates that sshd doesn't use any libraries besides libc,
    FMW> libcrypto and libz.

    FMW> Has anybody seen this behaviour?

    Clear posts get clear responses.

    Define "stops accepting." Does it close the listening socket so
    all connection attempts return ECONNREFUSED? Does the listening
    socket remain open but sshd itself not fork to handle the new
    session?

    Regards,

    Nicholas

    --
    "Why shouldn't I top-post?" [url]http://www.aglami.com/tpfaq.html[/url]
    "Meanings are another story." [url]http://www.ifas.org/wa/glossolalia.html[/url]
    Nicholas Dronen Guest

  3. #3

    Default Re: sshd goes catatonic on AIX 5.2 ML1

    Jurjen Oskam <joskamquadpro.stupendous.org> writes:
    > In article <87u181lxn7.fsfcicciolina.localdomain.localnet> , Florian M. Weps wrote:
    >
    > > Debugging output (sshd -ddd) was not helpful. The syslog 'auth'
    > > facility records only logins and sshd restarts.
    >
    > Then use truss to see exactly what sshd does.
    See below.

    You can see the last two good connections: sshd forks, does some
    housekeeping, and does a select waiting for a new conneciton (the
    "sleeping..." lines).

    The second one of those shows sshd going to sleep, but what it doesn't
    show is the attempts by ssh clients to wake it. It finally gets
    interrupted by the src's SIGTERM, when I typed "stopsrc -s sshd" after
    five minutes of failed login attempts.

    I can't see any difference between the two sequences.

    Thanks for your time,

    Cheers,
    Florian

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    _select(7, 0x20020DB8, 0x00000000, 0x00000000, 0x00000000) = 1
    naccept(3, 0x2FF22758, 0x2FF226B4) = 4
    kioctl(4, -2147195266, 0x2FF22600, 0x00000000) = 0
    kioctl(4, -2147195267, 0x2FF22600, 0x00000000) = 0
    kfcntl(4, F_SETFL, 0x00000000) = 0
    pipe(0x2FF226B8) = 0
    kfork() = 32656
    close(6) = 0
    _getpid() = 39094
    _getpid() = 39094
    close(4) = 0
    _select(7, 0x20020DB8, 0x00000000, 0x00000000, 0x00000000) = 1
    close(5) = 0
    _select(7, 0x20020DB8, 0x00000000, 0x00000000, 0x00000000) Err#4 EINTR
    Received signal #20, SIGCHLD [caught]
    kwaitpid(0x2FF22228, -1, 5, 0x00000000, 0x00000000) = 32656
    kwaitpid(0x2FF22228, -1, 5, 0x00000000, 0x00000000) Err#10 ECHILD
    _sigaction(20, 0x2FF221B8, 0x2FF221C8) = 0
    ksetcontext_sigreturn(0x2FF22270, 0x00000000, 0x2FF22FFC, 0x0000D0B2, 0x00000000, 0x60015015, 0x6000FA4F,
    +0x05C7BC00)
    _select(7, 0x20020DB8, 0x00000000, 0x00000000, 0x00000000) (sleeping...)
    _select(7, 0x20020DB8, 0x00000000, 0x00000000, 0x00000000) = 1
    naccept(3, 0x2FF22758, 0x2FF226B4) = 4
    kioctl(4, -2147195266, 0x2FF22600, 0x00000000) = 0
    kioctl(4, -2147195267, 0x2FF22600, 0x00000000) = 0
    kfcntl(4, F_SETFL, 0x00000000) = 0
    pipe(0x2FF226B8) = 0
    kfork() = 20170
    close(6) = 0
    _getpid() = 39094
    _getpid() = 39094
    close(4) = 0
    _select(7, 0x20020DB8, 0x00000000, 0x00000000, 0x00000000) = 1
    close(5) = 0
    _select(7, 0x20020DB8, 0x00000000, 0x00000000, 0x00000000) Err#4 EINTR
    Received signal #20, SIGCHLD [caught]
    kwaitpid(0x2FF22228, -1, 5, 0x00000000, 0x00000000) = 20170
    kwaitpid(0x2FF22228, -1, 5, 0x00000000, 0x00000000) Err#10 ECHILD
    _sigaction(20, 0x2FF221B8, 0x2FF221C8) = 0
    ksetcontext_sigreturn(0x2FF22270, 0x00000000, 0x2FF22FFC, 0x0000D0B2, 0x00000000, 0x60015015, 0x6000FA4F,
    +0x05C7BC00)
    _select(7, 0x20020DB8, 0x00000000, 0x00000000, 0x00000000) (sleeping...)
    _select(7, 0x20020DB8, 0x00000000, 0x00000000, 0x00000000) Err#4 EINTR
    Received signal #15, SIGTERM [caught]
    ksetcontext_sigreturn(0x2FF22270, 0x20000AE8, 0x2FF22270, 0x2FF3B820, 0x10002DE0, 0x0000D0B2, 0x05C7BC00,
    +0x2FF3AEC8)
    socket(1, 2, 0) = 4
    kfcntl(4, F_SETFD, 0x00000001) = 0
    connext(4, 0xF166D96C, 16) = 0
    _getpid() = 39094
    open(0xF166D93C, O_WRONLY|O_CREAT|O_TRUNC) = 5
    kioctl(5, 22528, 0x00000000, 0x00000000) Err#19 ENODEV
    kioctl(5, 22528, 0x00000000, 0x00000000) Err#19 ENODEV
    kwrite(5, " R e c e i v e d s i g".., 33) = 33
    close(5) = 0
    send(4, 0x2FF21564, 66, 0) = 66
    close(4) = 0
    close(3) = 0
    unlink("/usr/local/etc/sshd.pid") Err#2 ENOENT
    kfcntl(1, F_GETFL, 0x00000000) = 2049
    kfcntl(2, F_GETFL, 0x00000000) = 2049
    _exit(255)
    Florian M. Weps Guest

  4. #4

    Default Re: sshd goes catatonic on AIX 5.2 ML1

    Florian M. Weps <fwepsgreenmail.ch> wrote:
    FMW> Jurjen Oskam <joskamquadpro.stupendous.org> writes:
    >> In article <87u181lxn7.fsfcicciolina.localdomain.localnet> , Florian M. Weps wrote:
    >>
    >> > Debugging output (sshd -ddd) was not helpful. The syslog 'auth'
    >> > facility records only logins and sshd restarts.
    >>
    >> Then use truss to see exactly what sshd does.
    FMW> See below.

    FMW> You can see the last two good connections: sshd forks, does some
    FMW> housekeeping, and does a select waiting for a new conneciton (the
    FMW> "sleeping..." lines).

    FMW> The second one of those shows sshd going to sleep, but what it doesn't
    FMW> show is the attempts by ssh clients to wake it. It finally gets
    FMW> interrupted by the src's SIGTERM, when I typed "stopsrc -s sshd" after
    FMW> five minutes of failed login attempts.

    FMW> I can't see any difference between the two sequences.

    Please repost output with -f flag.

    [url]http://publib16.boulder.ibm.com/doc_link/en_US/a_doc_lib/cmds/aixcmds5/truss.htm[/url]

    -f Follows all children created by the fork system call and
    includes their signals, faults, and system calls in the
    trace output. Normally, only the first-level command or
    process is traced. When the -f flag is specified, the process
    id is included with each line of trace output to show which
    process executed the system call or received the signal.

    Regards,

    Nicholas

    --
    "Why shouldn't I top-post?" [url]http://www.aglami.com/tpfaq.html[/url]
    "Meanings are another story." [url]http://www.ifas.org/wa/glossolalia.html[/url]
    Nicholas Dronen Guest

  5. #5

    Default Re: sshd goes catatonic on AIX 5.2 ML1

    Florian M. Weps <fwepsgreenmail.ch> wrote:
    FMW> Nicholas Dronen <ndronenio.frii.com> writes:
    >> Please repost output with -f flag.
    FMW> It's huge (>300k compressed) - if you wish to look at it all, it's at

    FMW> [url]http://people.debian.org/~fmw/sshd.truss.gz[/url]

    FMW> 21002 is the sshd started by the SRC. This trace doents a script on
    FMW> another machine logging in every 10 seconds to run a single command,
    FMW> 'date'.

    FMW> The end of the trace is SRC stopping sshd after minutes of not caring
    FMW> about new connections - the last select() simply will not return even
    FMW> though clients are trying to connect.

    Hi, Florian:

    I spend 15 minutes or so looking at the truss output; I don't see anything
    amiss.

    Regards,

    Nicholas

    --
    "Why shouldn't I top-post?" [url]http://www.aglami.com/tpfaq.html[/url]
    "Meanings are another story." [url]http://www.ifas.org/wa/glossolalia.html[/url]
    Nicholas Dronen Guest

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