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ssh_exchange_identification: read: Connection reset by peer

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You may see this message when trying to use the ssh command:

ssh_exchange_identification: read: Connection reset by peer

These are the most likely reasons:

1. You're outside Informatics

When you're trying to login to one of the external login (ssh) servers from outside Informatics, several failed login attempts in a row may produce this error. This probably indicates that your ssh logins are now being blocked for security reasons. This block is triggered automatically whenever several login failures are made in a short space of time.

If this happens to you, just wait a while then try again - the block is only temporary. The block is triggered by only a few login failures. (The exact number varies, since OS platforms and ssh implementations do not all behave identically). Alternatively, if you urgently need access you can contact the User Support team (during office hours) and ask them to unblock you.

These temporary blocks help to defeat brute force attempts to guess your password. Our externally accessible machines are under constant attack, so we have to take steps to protect our machines, our data and our reputation.

To avoid being blocked, use Kerberos. With Kerberos you can authenticate to on your home machine before making a login attempt. This is a far more secure way of connecting, and since it avoids SSH password prompts, it avoids the automatic blocks. (Note though that this trick does not work on our remote desktop service.)

Find out more at these help pages:

2. You're trying to login to a cluster node

You'll probably get this message when you try to login directly to a cluster node, because direct logins to most cluster nodes are blocked. Try logging in to the cluster's head node. The clusters are listed at Cluster computing.

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