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 Post subject: Userids, Passwords and Malicious SHHD logins
PostPosted: Fri Sep 21, 2007 4:35 pm 
Senior Zenwalker
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Location: Sydney, Australia
The following article makes interesting if somewhat unsettling reading

    http://www.securityfocus.com/infocus/1876

We all, ofcourse, understand the necessity of strong userids and passwords, and if one is named paul, of the necessity of not using your name as a userid.

The problem is that by default Zenwalk is installed with SHHD ON by default. If you dont go on to fully configure SSHD properly, you leave yourself open to the sort of attacks discussed above. Now I'm not entirely sure whether, given that the new Zenwalk firewall stealths all the relevant ports (if it is turned on ofcourse), having an unconfigured SHHD running does pose a security risk and I will admit to not really being game to try it out.Perhaps someone else can shed some light on this.

As a matter of course I tend to turn off all services I dont intend to make use of and this includes SHHD when I am building a new system. If I need the services later I can start them up easily enough and get round to configuring them properly at the same time.

Regards

Michael

BTW I have no idea why paul is a commonly attacked userid. Are the more pauls running linux systems than any other persons or is there a cultural reference I'm missing  ???


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 Post subject: Re: Userids, Passwords and Malicious SHHD logins
PostPosted: Sun Sep 23, 2007 9:14 am 
Master of the known universe
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easy tricks to avoid ssh attacks (in sshd_config) :
- change ssh port
- use only protocol 2
- set PermitRootLogin to "no"

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 Post subject: Re: Userids, Passwords and Malicious SHHD logins
PostPosted: Sun Sep 23, 2007 5:55 pm 
Master Zenwalker
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guth wrote:
- change ssh port

Very usefull in avoiding scans from "random" machines. Another usefull trick would be to adapt your iptables rules so that ports are vulnerable only when you use a certain feature. Don't need ssh for now? Make the port invisible.


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 Post subject: Re: Userids, Passwords and Malicious SHHD logins
PostPosted: Sun Sep 23, 2007 11:15 pm 
Global Moderator
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I have discussed this with JP, and I believe he is inclined to turn SSH off by default. However, if your firewall - which I believe should be on by default on a vanilla install - is not allowing SSH logins, SSH running is not that much of an issue.

Since most users are not aware at all of what SSH actually does, it is a good idea not to enable it by default, however.

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 Post subject: Re: Userids, Passwords and Malicious SHHD logins
PostPosted: Mon Sep 24, 2007 2:43 am 
Senior Zenwalker
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Having just installed the Zenwalk 4.8 RC I note that the SSHD service has turned itsself on. All my other service settings and network setting seem to have held the way they were originally configured to be ie before the upgrade to 4.8 RC, only SSHD seems to have decided to start itself up at boot.

I don't know how difficult it is to set the default to off for this service in the full release of Zenwalk 4.8, but it would seem to be the preferable option.

Apart from that Zenwalk seems to have speeded up again.  :o  If you keep improving the performance of my old Pentium III I will have no valid excuses to go and buy a new toy ... I mean work computer  :)

Regards

Michael


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