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Tutorial: Set up Kojoney SSH Honeypot on CentOS 5.5

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Kojoney is a low level interaction honeypot that emulates an SSH server. The daemon is written in Python using the Twisted Conch libraries. In computer terminology, a honeypot is a trap set to detect, deflect, or in some manner counteract attempts at unauthorized use of information systems. Generally it consists of a computer, data, or a network site that appears to be part of a network, but is actually isolated, (un)protected, and monitored, and which seems to contain information or a resource of value to attackers. This tutorial shows how you can compile and install an updated version of Kojoney on a CentOS 5.5 server. read more...
mail this link | permapage | score:7977 | -falko, October 4, 2010

Tutorial: Set up RAID1 on a remote Linux system vis SSH

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RAID-1 allows to create an exact copy of the original drive. Thus, it results into the increased fault tolerance and easy data recovery option for single server. It is true that the best and easy way to setup a RAID 1 is during installation. But if you forget to setup RAID – 1 during installation or if you have added new hard disk after installation, then this how-to covers setting up a RAID-1 mirroring on a running remote Linux system over ssh session. read more...
permapage | score:7938 | -nixcraft, June 21, 2006

Opening SSH and HTTP ports with iptables

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How to use the command line to open ports on your iptables firewall under Linux.
I have to look this up from time to time, usually just after installing a new Linux system intended for use as a test server. There are GUI tools for configuring the firewall, but I usually leave the entire windowing system uninstalled.

By default, many Linux distributions will start up sshd and httpd, but you won’t be able to connect to them over the network, since the ports will be blocked by iptables. The examples below are for Red Hat or CentOS (which is basically Red Hat), and may vary slightly betweenl distributions.
read more...
mail this link | permapage | score:7887 | -Ray, January 9, 2006

Encrypted NFS with OpenSSH and Linux

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This make NFS over public networks an actual option, performance permitting.
"NFS is a widely deployed, mature, and understood protocol that allows computers to share files over a network. The main problems with NFS are that it relies on the inherently insecure UDP protocol, transactions are not encrypted, hosts and users cannot be easily authenticated, and its difficulty in firewalling. This article provides a solution to most of these problems for Linux clients and servers. These principles may also be applied to any UNIX server with ssh installed. This article assumes basic knowledge of NFS and firewalling for Linux."
read more...
mail this link | permapage | score:7830 | -Ray, February 15, 2002

Tutorial: Ultimate OpenSSH / Keychain Howto

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The fundamentals, starting with installation.
All right, so maybe this isn't quite the ultimate. But this howto will show you the fundamental ways to use OpenSSH; how to generate public/private key pairs and strong passphrases, and how to use the wonderful Keychain utility to automate your SSH logins. This is exceptionally handy when you log in and out frequently, and don't want to keep entering your passphrase.
read more...
permapage | score:7814 | -Ray, March 4, 2005

Set up SSH with Public-Key Authentication

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This guide explains how to set up an SSH server on Debian Etch with public-key authorization (and optionally with disabled password logins). SSH is a great tool to control Linux-based computers remotely. It is safe and secure. read more...
permapage | score:7745 | -falko, March 30, 2008

Restrict users to SCP and SFTP with Chrooted rssh on RHEL

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FTP is insecure protocol, but file-transfer is required all time. You can use OpenSSH Server to transfer file using SCP and SFTP (secure ftp) without setting up an FTP server. However, this feature also grants ssh shell access to a user.

In this article series we will help you provide secure restricted file-transfer services to your users without resorting to FTP. It also covers chroot jail setup instructions to lock down users to their own home directories (allow users to transfer files but not browse the entire Linux / UNIX file system of the server) as well as per user configurations. read more...
mail this link | permapage | score:7737 | -nixcraft, January 2, 2008

SSH as a SOCKS proxy

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Yet another sweet ability of OpenSSH...
The -D arg tells OpenSSH to be a SOCKS proxy. So you simply log in to the endpoint via SSH with the -D arg like:

ssh -D 1234 user@host.example.com

And then tell your web browser to use a SOCKS v5 proxy on localhost at the specified port and bingo, you have a secure connection to your endpoint.
read more...
permapage | score:7694 | -Ray, January 23, 2009

Tutorial: Mount remote directories with SSHFS (Debian 6)

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This tutorial explains how you can mount a directory from a remote server on the local server securely using SSHFS. SSHFS (Secure SHell FileSystem) is a filesystem that serves files/directories securely over SSH, and local users can use them just as if the were local files/directories. On the local computer, the remote share is mounted via FUSE (Filesystem in Userspace). I will use Debian Squeeze for both the local and the remote server. read more...
permapage | score:7668 | -falko, September 22, 2011

Tutorial: SMTP over an SSH tunnel

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Make your email a little bit more private with the Secure Shell.
It is widely known that POP3 is a very insecure protocol, since it is a plain text protocol that transmits passwords and usernames with no protection. Anyone on a private network can quickly sniff packets and determine all the passwords used on the network. Although advances in POP3 authentication have surfaced (APOP, SSL, etc.) many servers still use the old plain text format.

SSH tunneling is the process of establishing a secure, encrypted tunnel between you and the mail host. This tunnel can be used for anything, but by using the Precommand feature of KMail, I will show you how to use a tunnel for POP3 and SMTP.
read more...
mail this link | permapage | score:7653 | -Ray, May 20, 2001 (Updated: June 8, 2003)

Compiling OpenSSH on Ubuntu Server

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Find out how to compile OpenSSH on the latest version of Ubuntu, Ubuntu 7.04 Feisty Fawn Server, to get safely connected to your remote servers.
Installing the OpenSSH client and server on Ubuntu is as easy as typing "sudo apt-get install openssh" at a terminal prompt. However, this will install Portable OpenSSH version 4.3p2[-8ubuntu1]. Unfortunately for users, this version of Portable OpenSSH does not include the "Match" functionality added to the SSH server in version 4.4p1, that "allows some configuration options to be selectively overridden if specific criteria (based on user, group, hostname and/or address) are met."
read more...
mail this link | permapage | score:7645 | -estride, May 31, 2007

Use SSH via HTTP Proxy with Corkscrew

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If you want to ssh your vps server or your home computer from your work place (assuming you are using http proxy). You need to use Corkscrew. Corkscrew is a simple tool to tunnel TCP connections through an HTTP proxy supporting the CONNECT method. It reads stdin and writes to stdout during the connection, just like netcat. read more...
permapage | score:7645 | -gg234, December 29, 2008

Tutorial: Disable SSH, use scponly for file transfer (Debian 6)

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scponly is an alternate shell that restricts users to SCP and SFTP logins, but disallows SSH logins. It is a wrapper to the OpenSSH suite of applications. With the help of scponly, you can allow your users to use clients such as WinSCP or FileZilla to upload/download files, but you refuse SSH logins (e.g. with PuTTY) so that your users cannot execute files/programs. This tutorial shows how to install and use scponly on Debian Squeeze. read more...
permapage | score:7573 | -falko, August 24, 2011

Make SSH connections with SSHMenu

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SSHMenu overview and usage tips...
SSHMenu is packaged and available in repositories for both Ubuntu (as sshmenu-gnome) and Fedora (gnome-applet-sshmenu). Other SSHMenu packages available for both distributions do not include GNOME support. In those, the button for the SSH menu is started in its own window and an xterm is started when you wish to connect to a host with SSH. If you install the GNOME-aware SSHMenu packages, you can add SSHMenu to your panel by right-clicking the panel and choosing "Add to Panel..." and selecting the "SSH Menu Applet." When using the GNOME-aware SSHMenu, a gnome-terminal is started to handle your SSH connections, and you can select the profile gnome-terminal should use on a per-host basis.
read more...
mail this link | permapage | score:7525 | -Ray, June 18, 2008

Using SSH and SCP without passwords

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Setting up SSH user equivalency makes it extremely convenient to propagate files, either manually or via scripts for backups, etc. For some environments, such as Oracle Grid, ssh user equivalency is necessary for some tools to function.
In this article, I show you how to use the scp (secure copy) command without needing to use passwords. I then show you how to use this command in two scripts. One script lets you copy a file to multiple Linux boxes on your network, and the other allows you to back up all of your Linux boxes easily.

[ . . . ]

But what I like best about scp is it's easily scriptable...
read more...
mail this link | permapage | score:7508 | -Ray, October 9, 2005

Tutorial: OpenSSH Security Practices

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OpenSSH is the implementation of the SSH protocol. OpenSSH is recommended for remote login, making backups, remote file transfer via scp or sftp, and much more. SSH is perfect to keep confidentiality and integrity for data exchanged between two networks and systems. However, the main advantage is server authentication, through the use of public key cryptography. From time to time there are rumors about OpenSSH zero day exploit. Here are a few things you need to tweak in order to improve OpenSSH server security. read more...
mail this link | permapage | score:7485 | -nixcraft, July 27, 2009

Securing SSH

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Yes, even OpenSSH is vulnerable...
Apart from past flaws in the OpenSSH daemon itself that have allowed remote compromise (very rare), most break-ins result from successful brute-force attacks. You can see them in your firewall, system or auth logs, they are an extremely common form of attack. Here is an excerpt from the /var/log/messages file on a CentOS Linux box (the attacking hostname has been obfuscated). You can see multiple attempts to login as users root and ftp. Also note the time between repeated attempts - one second or less, much too quick to be a human. This is an automated attack.
read more...
mail this link | permapage | score:7419 | -Ray, April 25, 2006

Restricting SSH commands

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Automate rsync backups without opening everything else...
SSH is a powerful tool. When combined with ssh keys, it becomes easy to automate remote procedures like backups. However leaving key access wide open can be a bad idea. It is possible to use restrict ssh keys to specific commands, even comming from specific hosts. There is this nice little perl script called Authprogs that makes this somewhat easier. Ill show you how to use authprogs for an automated rsync over ssh.
read more...
mail this link | permapage | score:7398 | -Ray, February 14, 2008

Tutorial: SSH Port forwarding

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This guide will get you up and tunneling your sessions over encrypted network connections.
SSH stands for Secure SHell, and it works very similar to the other login programs (it's based on Rsh, actually) with one important difference - it encrypts the entire communication session. When you enter your login and password they are encrypted before being sent. Likewise, everything you type and everything that comes back to you is encrypted as long as you're within that SSH session. The concept is very similar to how the military scrambles their radio communications to keep them from being intercepted by the enemy.
[If you still have problems in forwarding sessions over encrypted tunnels after reading the guide in the [read more] link below, try alternate SSH tunneling tutorial. -Ed] read more...
mail this link | permapage | score:7361 | -BluNereid, March 18, 2001 (Updated: April 1, 2005)

SSHFS Tutorial: How to use the SSH filesystem

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This short and sweet article has the steps you need to set up and use sshfs.
SSHFS is a really nice piece of software, because it just makes your life just a bit easier. It can 'mount' a directory of a remote SSH server and you can use it as a normal directory.
read more...
permapage | score:7344 | -Ray, August 23, 2006 (Updated: March 24, 2007)
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