unable to allocate pty: error: session_pty_req: session 0 - SSH

This is a discussion on unable to allocate pty: error: session_pty_req: session 0 - SSH ; Hello all, I am unable to ssh into a diskless host running Fedora. When I boot into the golden image (same kernel and root files), I can ssh. Perhaps I'm missing something? Description: Fedora 6 - kernel: 2.6.22.14 which I ...

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Thread: unable to allocate pty: error: session_pty_req: session 0

  1. unable to allocate pty: error: session_pty_req: session 0

    Hello all,

    I am unable to ssh into a diskless host running Fedora. When I boot
    into the golden image (same kernel and root files), I can ssh.
    Perhaps I'm missing something?

    Description: Fedora 6 - kernel: 2.6.22.14 which I recompiled in
    order to make the necessary kernel changes to support NFSROOT.

    Problem: The host boots ok via PXE as expected. I can login into the
    host via tty. Attempts to ssh from another host causes it to hang. I
    checked its /var/log/secure message and found the following:

    Feb 28 17:55:09 localhost sshd[2964]: Accepted password for sofia from
    127.0.0.1 port 36123 ssh2
    Feb 28 17:55:09 localhost sshd[2964]: error: openpty: No such file or
    directory
    Feb 28 17:55:09 localhost sshd[2966]: error: session_pty_req: session
    0 alloc failed

    1. I also tried to ssh to localhost on the machine, it hangs too.
    2. I looked at the /dev/pts - and I notice that nothing is created
    there.
    3. I boot into the golden image running same kernel but root is on
    disk. I can successfully ssh into this box; and notice that when
    ssh'ing the /dev/pts/0 directory(ies) are created appropriately.

    4. As I googled further ... I stumbled into a suggestion to perform
    the following:

    ssh bash -i

    I performed this, and I am able to ssh into the box:

    [sofia@test1 tmp]# ssh 192.168.16.29 bash -i
    sofia@192.168.16.29's password:
    [sofia@localhost ~]# ls -al
    total 200

    .....

    Any thought? Perhaps I'm missing something obvious ...(or did I miss
    some relevant files when I tar'ed into my NFS/PXE server?).

    Thanks in advance.

    --
    best,

    Vince

  2. Re: unable to allocate pty: error: session_pty_req: session 0

    On 2008-02-29, v i n c e wrote:
    > Hello all,
    >
    > I am unable to ssh into a diskless host running Fedora. When I boot
    > into the golden image (same kernel and root files), I can ssh.
    > Perhaps I'm missing something?
    >
    > Description: Fedora 6 - kernel: 2.6.22.14 which I recompiled in
    > order to make the necessary kernel changes to support NFSROOT.
    >
    > Problem: The host boots ok via PXE as expected. I can login into the
    > host via tty. Attempts to ssh from another host causes it to hang. I
    > checked its /var/log/secure message and found the following:
    >
    > Feb 28 17:55:09 localhost sshd[2964]: Accepted password for sofia from
    > 127.0.0.1 port 36123 ssh2
    > Feb 28 17:55:09 localhost sshd[2964]: error: openpty: No such file or
    > directory
    > Feb 28 17:55:09 localhost sshd[2966]: error: session_pty_req: session
    > 0 alloc failed
    >
    > 1. I also tried to ssh to localhost on the machine, it hangs too.
    > 2. I looked at the /dev/pts - and I notice that nothing is created
    > there.
    > 3. I boot into the golden image running same kernel but root is on
    > disk. I can successfully ssh into this box; and notice that when
    > ssh'ing the /dev/pts/0 directory(ies) are created appropriately.
    >
    > 4. As I googled further ... I stumbled into a suggestion to perform
    > the following:
    >
    > ssh bash -i
    >
    > I performed this, and I am able to ssh into the box:
    >
    > [sofia@test1 tmp]# ssh 192.168.16.29 bash -i
    > sofia@192.168.16.29's password:
    > [sofia@localhost ~]# ls -al
    > total 200
    >
    > ....
    >
    > Any thought? Perhaps I'm missing something obvious ...(or did I miss
    > some relevant files when I tar'ed into my NFS/PXE server?).


    Depending on what options you compiled into your kernel, you probably
    need to either mount the pts filesystem ("mount -t devpts devpts /dev/pts")
    or create some pty device nodes in /dev ("/dev/MAKEDEV pty").

    --
    Darren Tucker (dtucker at zip.com.au)
    GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4 37C9 C982 80C7 8FF4 FA69
    Good judgement comes with experience. Unfortunately, the experience
    usually comes from bad judgement.

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