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Password-less SSH and Autofs

Submitted by on May 15, 2011 – 4:04 am 6 Comments

Recently I’ve ran into an unusual problem with SSH on SLES 11 SP1. The system – a small HPC cluster – is configured to use NIS for authentication and automounter maps. Whenever a user logs in, the home directory is automounted from an external NAS. Each user has a ~/.ssh directory with the authorized_keys2 and known_hosts required for password-less SSH access among the cluster nodes.

On the one hand, this configuration is useful because you only need to have one ~/.ssh directory, which is then automatically mounted on whatever system you are trying to access. The drawback is that, apparently, there is a risk of a chicken-or-egg paradox. In order to authenticate you, sshd on the target node needs to access your ~/.ssh, which needs to be automounted first, which in turn requires successful authentication. Sometimes password-less SSH failed because the home directory was not automounted.

In my experience, this problem is unique to SLES 11 SP1. I have not seen it on any other SLES or RHEL cluster with identical NIS/autofs configuration. I found that starting or restarting ypbind and autofs after sshd started helps avoid this problem. The simplest way to do this is to add “/etc/init.d/ypbind restart ; /etc/init.d/autofs restart” line at the end of your /etc/init.d/sshd startup section. A dirty fix to be sure, but it seems to work just fine.

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  • Cupcakerum says:

    I have a jailbroken iPhone 3G. How do I download/get SSH on my iPhone so I can use Cyder and install apps from my computer. I need this because my wifi feature died and doing it from the computer is the only way I have left.

  • sam N says:

    The SSH client on the switch is enabled.

    Communication between the switch and remote users is encrypted.

    A username/password combination is no longer needed to establish a secure remote connection to the switch.

    The switch requires remote connections via proprietary client software.

  • forahobby says:

    I am tired of having to plug my ipod into my computer to put new music on it. I was wondering how i could do this using ssh. I would also rather it be put on the music app not something like dTunes.

  • Dark_LovexXx says:

    I’m looking at running SSH on my school laptop because pretty much everything useful has been blocked, but I don’t want to run my home internet cap over by doing this. If i use an SSH tunnel to get past the proxy will I use up my home internet cap?

  • nothin_nyce1 says:

    My friend set up a vps I can download torrents onto, then use SSH to get them onto my computer. He said it’s encrypted and my ip is totally hidden/anonymous. Is this true that nobody, not even my isp can see?

  • Ed D says:

    i have tried WINscp and disk-aid but is there a good free ssh program???
    any help is much appreiated.

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