How Server! prevents SSHPsycho attacks Server! version: 4.0.0+

According to the SANS ISC nearly 80% of all SSH-based brute force attacks are caused by SSHPsycho or one of its variations. This seems to be confirmed by the LongTail honeypot real-time report provided by the Marist College. So, yes, SSHPsycho is a big deal, and it’s a problem. And traditional blacklisting mechanisms (simply banning certain “well known” IP addresses and networks) have proved to be inefficient against it.

LongTail shows that Cisco and Level 3’s recent announcement about blocking sshPsycho’s 4 class C IP ranges (also known as “Group 93” and the “Hee Thai Campaign”) has done nothing to stop their brutal attacks. [Source: SANS ISC] Server!’s intelligent and automatic blacklist (called “Protector“), though, shows to be extremely effective at preventing such type of attack. Its real-time dynamic attack pattern identification and prevention technology can quickly recognize SSHPsycho attacks (and the like) and proactively stop them as soon as they begin. Even at its “Normal” sensitivity threshold, Protector already identifies and blocks all types of SSHPsycho attacks, in most cases before they even get to try the password authentication. Continue reading Server!: VFS with quotas Server! version: 4.0.0+

The Virtual File System (VFS) instroduced in Server! v4.0, comes with a long-awaited feature: quota management.

The Windows OS features a very powerful yet complicated quota management, but it’s only available in Windows Server editions and requires optional features to be installed, therefore we could not rely on that and we built our own quota management system which is cross-compatible with all Windows systems.

Now, the problem with quota management is that calculating the current size of a folder (along with its sub-folders) can be very time-consuming, if the folder contains millions and millions of files. So if we were to re-evaluate the size to enforce quota restrictions at every operation it could totally kill the performances. Our solution the Quota TTL, which is the Time-To-Live (TTL) of the quota cache, expressed in seconds. Basically, when Server! calculates the current size of a folder structure, it will consider such result valid for QuotaTTL seconds, without re-evaluating it too often. Continue reading Server! v4: new format to define groups Server! version: 4.0.0+

From Server! v1 through v3 groups’ usernames used to start with a star/asterisk and then the group name enclosed within square brackets. For example the SFTP Users group would have the following username: *[SFTP Users]

In version 4 we have removed the star/asterisk, because we have introduced the concept of user type. Therefore in version 4 the SFTP Users group will be defined as follows.
Username: [sftp users]
User Type: Windows Group or Active Directory Group Continue reading

HTTPS “connection not private/secure” – what it is? Server! version: 4.0.0+

After installing Server! v4.0 you will be able to manage it securely via web interface over HTTPS.

Now, a very common choice is to use a self-signed certificate, because it saves money and if you know what you’re doing it doesn’t compromise security. This is, in fact, the most common choice among our users (according to our surveys).

But if you use a self-signed certificate, your browser will warn you that your connection may not be private or secure. That’s because self-signed certificates are often used for man-in-the-middle (MitM) attacks. But this is not the case, of course, if you can verify that this particular self-signed certificate was created by you and for you.

To get rid of this annoying message, you basically have 2 options:

  1. Spend some money to buy a trusted X.509 (SSL/TLS) certificate from a Certification Authority like DigiCert, Comodo, Thawte, and the like. It goes without saying that this is the recommended choice, as it takes advantage of the inherent trust chain provided by the Certification Authority.
  2. Verify and accept the self-signed certificate you have just created and add it to the trusted keychain of your browser. In this case you are advised to always verify the certificate’s fingerprint to make sure it’s really the one you created yourself, and that you’re not a victim of a Man-in-the-Middle (MitM) attack.

Continue reading

Understanding the security “preset configuration” Server! version: 4.0.0+

In the new Server! v4.0, there’s a quite handy feature that allows a one-click configuration of many security settings at once, depending on the virtual server’s intended usage scenario.


Here’s a brief explanation of what each preset configuration means and what to expect when you apply it: Continue reading

How to put users’ homes on shared folders Server! version: 4.0.5+

Some of our Server! users prefer to store their users’ home folders (actually VFSs as of version 4.0) on a different machine via shared folders. For example, instead of having your user’s home point to C:\SFTPData\MyUser you want to have it point to \\\SFTPData\MyUser.

This is a perfectly reasonable and fairly common request. As of version 4.0, Server! provides a variety of methods to accomplish this goal.

The first step is always the same: creating a VFS that points to the network-shared folder, like this:


Once the VFS is created, you can proceed and create a User profile that uses the newly created VFS as its “home”. And this is where you have many options.

For example, if your entire infrastructure runs on Windows (including the machine that shares the folder) and all your systems are ActiveDirectory-aware, then you can specify the user type as “Active Directory” and impersonate the home VFS as “this user”: Continue reading Server! v4.0.2 Released!

We have just released version 4.0.2 of our Server! software. This hot-fix release was necessary to address an issue with some of the upgrades from version 3.x to version 4.0 where – at times – a “path not found” error could appear during the upgrade process.

We apologize for any inconvenience, and recommend anyone that needs to upgrade from version 3.x to download this new hot-fix release.

A great SFTP client for Mac? Here it is!

Quite often our Server! customers and users contact us asking for recommendations regarding the choice of an SFTP client for MacOSX.

Of course there are several options out there. And then there’s Commander One by Eltima Software, the two-pane file manager for MacOSX that will make you forget anything else you’ve tried before on the Apple platform.

Not only it supports FTP, FTPS and SFTP, but also provides some highly desirable features like dual-pane tabbed browsing, support for compressed archives, regular-expression file searches, and even server-to-server file copies.

Our developers here at Syncplify have downloaded it and tested it thoroughly, and Commander One turned out to be an excellent software product, well designed, feature rich, and easy to use. For such reasons we feel comfortable recommending it to our users and customers as a great Mac client to connect to our Server! Server! v4: scripting framework differences Server! version: 4.0.0+

The scripting framework in Server! v4.0, which is used by the event-handling subsystem, is significantly different from the one found in previous versions. Yet, we did our best to preserve backward compatibility for the scripts you may have written in the past. Continue reading