The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘SSH’ Category

Differences between SFTP and “FTP over SSH” – Stack Overflow

Posted by jpluimers on 2016/10/13

As I will likely have to secure some external FTP sessions soon and the endpoints the current FTP connects to are vague in what they support:

Here is the difference:

  • SFTP (SSH file transfer protocol) is a protocol that provides file transfer and manipulation capabilities. It can work over any reliable data stream, but is typically used with SSH
  • “FTP over SSH” uses the regular old FTP protocol, but an SSH tunnel is placed between client and server.

Source: Kristopher Johnson answering in c# – Differences between SFTP and “FTP over SSH” – Stack Overflow

–jeroen

Posted in Communications Development, Development, Internet protocol suite, Software Development, SSH, TCP, TLS | Leave a Comment »

OpenSSH/Logging and Troubleshooting – 

Posted by jpluimers on 2016/09/19

For my own link history: Debugging a server configuration

Source: OpenSSH/Logging and Troubleshooting – Wikibooks, open books for an open world

Posted in Communications Development, Development, Internet protocol suite, SSH, TCP | Leave a Comment »

tombh/texttop: A fully interactive X Linux desktop rendered in TTY and streamable over SSH

Posted by jpluimers on 2016/08/09

Wonder if I can get this to work from macOS / OS X as a client:

texttop – A fully interactive X Linux desktop rendered in TTY and streamable over SSH

Source: tombh/texttop: A fully interactive X Linux desktop rendered in TTY and streamable over SSH

via: Kristian Köhntopp – Google+

Read the rest of this entry »

Posted in *nix, *nix-tools, Communications Development, Development, Internet protocol suite, Linux, Power User, Software Development, SSH, TCP | Leave a Comment »

Latest Tumbleweed distribution update likely kills sshd

Posted by jpluimers on 2016/05/03

After a recent big update to OpenSuSE Tumbleweed, I could not ssh into my system any more.

Symptoms

The ssh client side would report a Read from socket failed: Connection reset by peer which I misinterpreted as the sshd not running at all.

Luckily the server is a VM, so I could reach the console. There I saw this:

sshd trying to load files it shouldn't

sshd trying to load files it shouldn’t

The files should not be loaded as they are not specified in the sshd_config file:

dsa and ecdsa not specified in the config file

dsa and ecdsa not specified in the config file

So I knew something was broken. After reading some messages in the forums.opensuse.org I got at Bug 977812 – sshd killed by SIGSYS on client connection

The cause

As usual with such issues the cause seems a combination of factors:

And we have the culprit, I believe: together with the glibc upgrade, openssl
was updated from 1.0.2g-1.1 to 1.0.2-2.12 which brought, among others, patch
openssl-urandom-reseeding.patch.

Temporary fix

A temporary fix is to comment out a line in /etc/sshd_config so you get this diff:

-UsePrivilegeSeparation sandbox # Default for new installations.
+# UsePrivilegeSeparation sandbox # Default for new installations.

Be sure to undo this as soon as you’ve received a final fix.

Final fix

A final fix is being fast-tracked so it appears in Tumbleweed soon.

I will report after deployment of [opensuse-factory] New Tumbleweed snapshot 20160502 released! as I think it contains the fix.

Aftermath

I already knew about openQA: Test summary which lists the builds, but not the changes in the builds.

Reading through Information Board or the like for Tumbleweed I found the openSUSE Mailinglist Archive: opensuse-factory which does the announcements and release notes for Tumbleweed.

It had both the announcement of the “big patch”, ssh bug report and temporary fix:

–jeroen

 

 

Posted in *nix, Communications Development, Development, Internet protocol suite, Linux, openSuSE, Power User, SSH, SuSE Linux, TCP, Tumbleweed | 2 Comments »

Research notes on Diffie Hellman over WebSockets over a MittM http proxy to setup an encapsulated secure channel

Posted by jpluimers on 2015/06/17

Inspired by CloudFlare Keyless SSL, I have this idea of using Diffie Hellman over WebSockets over a MittM based http proxy (which intercepts and decrypts HTTPS traffic) like mitmproxy (but them from a commercial vendor to inspect web traffic) to setup an encapsulated secure channel.

I know SSH uses Diffie Hellman to setup a secure channel over a binary TCP connection.

Binary communication over HTTP usually means WebSocket.

I don’t want WebSSH (which does use WebSockets, but is probably filtered by the MitM proxy anyway).

Maybe either of these open source tools will work:

If these don’t work, I need to do more research.

Since I use C# and .NET for much of my work, I started the WebSocket over HTTP C# query.

c# – How to use proxies with the WebSocket4Net library – Stack Overflow.

–jeroen

Posted in *nix, *nix-tools, Communications Development, Development, HTTP, Internet protocol suite, Linux, Power User, SSH, SuSE Linux, TCP, WebSockets, Windows, Windows-Http-Proxy | Leave a Comment »

More secure SSH: hardening both client and server. And use Tor

Posted by jpluimers on 2015/01/26

Thanks Jan Wildeboer for sharing a link to https://stribika.github.io/2015/01/04/secure-secure-shell.html.

That describes how to harden your secure shell by configuring the most secure algorithms for it.

Related: [WayBack] encryption – What are ssh-keygen best practices? – Information Security Stack Exchange

–jeroen

via More secure SSH. https://stribika.github.io/2015/01/04/secure-secure-shell.html.

Posted in *nix, *nix-tools, Communications Development, Development, Internet protocol suite, Power User, SSH, TCP | Leave a Comment »