Olav,

If I had to guess - the problem is most likely to be a shortage of 'entropy'.

IRRC MPE/iX and HP-UX are alike in that they don't have a 'kernel entropy/random data source' - as Linux and some other Un*x's do.

Under MPE/iX we have 'EGD' (the Entropy Gathering Daemon) to generate the 'random' data that ssh/sshd/sftp/scp needs to work properly.  Making the initial connection requires the most amount - and can easily 'drain' the entropy source.  Lots of connections means lots of random data needed.  No random data=no encryption - so 'ssh' based things nearly always 'stop'.  I suspect that the HP-UX port uses EGD as well. (ssh's second biggest use of random data is to pad out transmission blocks that aren't full).

Check your entropy source - and make sure it's producing sufficient quantity of 'random' data.

The 'EGD' used w/the MPE/iX port of OpenSSH is written in Perl and can be customized to specify more sources, if necessary.  Each system's usage/access profiles will help determine what things can be 'harvested' for this data.  Ideally, it should be 'non-determinant' data (stuff you can't predict or influence), in order to keep the data sufficiently random.

If your 'UX' system's entropy source isn't producing enough - there are several alternatives that produce more 'random' data than EGD does, with the trade-off of it not being quite as 'random'.  Let me know if you need pointers to these alternatives.

If that's not it - check the nohup.out for the sshd or pipe the output into a log-file, looking for more clues.  If necessary, you can specify either '-v' options to get trace data.  Is this a 'one off' event, or a recurring problem?  What kind of activity is occuring during the failures?

If you don't want to post potentially sensitive debugging data - feel free to contact me off-list.

Thx,

-Brian Edminster
Applied Technologies, Inc

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