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I think ths is a general question but I'm not sure if it needs to be migrated because of the technical and security related nature of the beast in question.

For my current client we have an SFTP key set up in FileZilla to configure our current connection and file transfers.

This is a multi-user environment, we have around 50-60 people who could-would potentially use this key at any given time.

I keep getting errors when logging in, and when I reach out to the company that hosts the FTP servers, they tell me

"Multiple users have logged in without a log out. We don't support this."

My question is:

Why in a multi-user environment, would this be an appropriate set-up? Wouldn't you in fact expect this behavior, and try and support it for a given block of IP Addresses?

Is there some recommendation I could make for this set up to make it easier for us to access this server? I know it's probably subject to company policy, but it's quite frustrating..

Perhaps I'm missing something from a security standpoint, but I just can't wrap my mind around it. Thanks!

ERROR: disconnected: No supported authetnication methods available (server sent:)

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By errors you mean...? – Nathan C May 1 '14 at 12:47
disconnected: No supported authetnication methods available (server sent:) – Hituptony May 1 '14 at 12:48

2 Answers 2

up vote 0 down vote accepted

This appears to be a configuration issue on the server. Sometimes a server administrator will configure the server so that any given user may only have X active connections to the server at any given time; especially from a single IP address.

There are a few reasons that server administrators will do this: 1) sometimes SFTP clients will open multiple connections to transfer many files at the same time, which could eat up bandwidth and choke out other users trying to connect to the server, and 2) sometimes users will share 1 single login with 50 users so everyone can log in with the same credentials (as is your case). As mentioned previously, this degrades security and server administrators' ability to figure out which user is taxing the system, especially if 50 logins are coming from the same IP address, as would be the case if all those users were on a lan funneling through the same router to the remote SFTP server.

You could contact the Server Administrator for the remote SFTP server and ask them what the Active Connection Limit is per IP address and/or per user account, or you could switch to a more secure client configuration where each user has their own creadentials to the server.

Hope that helps!

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great answer, stole it! – Hituptony May 5 '14 at 15:27

I would not consider an environment, where all users login with the same key a multi-user environment. If you have multiple users you should have multiple logins. And if you share the same private key between 50..60 users you no longer can consider it private, which defeats security.

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and i know it probably should be one user-id = one user but in this case I think we all share a I'm somewhat confused by this – Hituptony May 1 '14 at 13:46
is there some recommendation I could make for this set up to make it easier for us to access this server, I know it's probably subject to company policy, but it's quite frustrating – Hituptony May 1 '14 at 13:47
I don't know any details about your relationship with the hosting company, but often there are different packages for different kinds of customers (e.g. small companies vs. bigger or based on the needed features) and one needs to pick the appropriate one. – Steffen Ullrich May 1 '14 at 16:34

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