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MOUSE problem in Centos 5.1
by Gopinath Achari 23 Jul '08

23 Jul '08

HI All, i installed Cent OS 5.1 on a INtel P4 PC. it got installed successfully. Upto the login prompt the mouse cursor appears on the screen. then cursor disappers. i we move the mouse. the cursor movement is felt when it is on a icon or when right click is done but the cursor is transparent. i dont know what is the problem. the mouse cursor is seen on the CUI prompt but not in GUI. Please help me what to do. the mouse is of Logitech make and is a ball mouse Regards, Gopinath

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Re: [CentOS] Ideas for stopping ssh brute force attacks
by Les Bell 23 Jul '08

23 Jul '08

"David Dyer-Bennet" <dd-b(a)dd-b.net> wrote: >> Yes, but if there are *any* ports exposed, seems like those are equally possible. << Sort of. Changing the port used by sshd stops the completely clueless script kiddies, since they don't even bother looking at anything other than port 22. Putting it way up high, among the ephemeral ports, will slow down the slightly more clueful who perform nmap scans, since nmap only scans around 1500 ports by default, and if sshd isn't running on one of those, they won't spot it. However, it won't deter the intelligent or curious attacker; these guys will scan all ports (slowly, so you may not even notice them) and they will use banner enumeration to identify the services, rather than assuming. Moving sshd to a non-standard port is one of the worst examples of relying on security by obscurity. Its only advantage is that it cuts out some noise in the logs, but proper precautions do that as well, without lulling you into a false sense of security. Rate limiting, combined with enforcement of really strong passwords, or even better, public/private key authentication, is real security. A useful additional layer of defence, if you want it, is a daemon that will watch for port scans on the simple services ports and immediately insert a firewall rule to block that source - such as the old PortSentry, if you can find it, or some more modern equivalent. Of course, this won't do much to defend against some types of stealthy scans, such as idle time scans. Best, --- Les Bell, RHCE, CISSP [http://www.lesbell.com.au] Tel: +61 2 9451 1144 FreeWorldDialup: 800909

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OT: Making BT/Yahoo account accessible to plain router
by Anne Wilson 23 Jul '08

23 Jul '08

My daughter has a BT account, with a BT supplied single-port router. I'd like to replace it with a standard router, but the settings appear to be totally hidden. If anyone reading uses BT, could you please tell me where to find the info? Maybe off-list, to save bandwidth for others/ Thanks Anne

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TLA -- GNU Arch 1
by Robert Moskowitz 23 Jul '08

23 Jul '08

Was it ever a part of Centos? Supposedly I need it and my colleague is providing me with an rpm, but he implies that 'seems to have been removed from Centos'?

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VNC server problem
by Gopinath Achari 23 Jul '08

23 Jul '08

HI all, i am configuring VNC server in CentOS 5.1. i have enables this two lines in /etc/sysconfig/vncserver file VNCSERVERS="2:vnc" VNCSERVERARGS[2]="-geometry 1024x768 -depth 24" here i have created a user vnc and set the password using vncpasswd cmd. then i started the vncserver # vncserver New 'localhost.localdomain:1 (gopinath)' desktop is localhost.localdomain:1 Starting applications specified in /root/.vnc/xstartup Log file is /root/.vnc/localhost.localdomain:1.log The above message was displayed about executing vncserver command. no OK status was displayed. then i used cmd vncviewer localhost.localdomain:5901 it prompted for the passwd i gave the password then it started vncviewer but in that only cursor is displayed which can be moved. but no GUI display. Please help me on this if any one knows i am still a beginner to linux

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how do I stop X / gnome via SSH?
by Rudi Ahlers 23 Jul '08

23 Jul '08

Hi all I need to disable / stop X from running on a remote server, to which I only have SSH access, and I have never done this before. So, can someone please tell me how todo it? -- Kind Regards Rudi Ahlers Check out my technical blog, http://blog.softdux.com for Linux or other technical stuff

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Re: [CentOS] Re: Ideas for stopping ssh brute force attacks
by Scott Mazur 23 Jul '08

23 Jul '08

On Wed, 23 Jul 2008 10:10:14 +1000, Les Bell wrote > Scott Silva <ssilva(a)sgvwater.com> wrote: > > >> > Portsentry is still available on sourceforge I believe. > << > > Good call - http://sourceforge.net/projects/sentrytools/ shows they were > uploaded back in 2003 and it looks like nothing has happened since then. > There must be more modern equivalents, surely? I wrote a Perl daemon that I use to tail service log files. Initially it was a Postfix log scanner that looked for unknown address attempts, relay attempts, and honey pot email addresses that I embedded in my web pages. When any of these hits turned up in the mail log, the senders IP was added to the iptables rules. My goal was to cut down on spam. It helped some, but not enough to call it a complete success. But it's very modular. I started having some problems with brute force ftp attacks. Very annoying, kept filling up the log files (and my log partition) with chaff. So I wrote another module for my daemon to scan the ftp logs as well and firewall any ip that failed to log in after 10 tries (a 3 hour time out). This was very successful and now ftp crack attacks are a thing of the past. I've never had ssh problems. My ssh port rules limited it to a few known IP addresses that I may need remote access from. But my Perl daemon could be easily expanded with another module to scan for ssh attacks. Provided you've got some Perl experience and time to hack (I'm hog tied for the next while). Scott -- Registered Linux user #395249, http://counter.li.org Nothing goes to waste when Little Fish are near! (http://www.littlefish.ca)

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Sendmail conf
by Joseph L. Casale 23 Jul '08

23 Jul '08

A long time ago someone helped me with setting up sendmail to simply queue and relay mail. They suggested: 1) edit /etc/sysconfig/sendmail and set "DAEMON=no" 2) edit /etc/mail/submit.mc and set FEATURE(`msp', `[IP.of.relayhost]')dnl Given the sendmail-cf RPM is already installed a "service sendmail restart" is enough to a light, direct submitting sendmail setup. How does one rewrite all mail to one specific address so it can be filtered by a user that receives all mail for this host? Can there be a rule in place with the above config? Hopefully that is just as easy in sendmail as it is postfix! Thanks! jlc

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Re: [CentOS] Re: Ideas for stopping ssh brute force attacks
by Les Bell 23 Jul '08

23 Jul '08

Scott Silva <ssilva(a)sgvwater.com> wrote: >> Portsentry is still available on sourceforge I believe. << Good call - http://sourceforge.net/projects/sentrytools/ shows they were uploaded back in 2003 and it looks like nothing has happened since then. There must be more modern equivalents, surely? Best, --- Les Bell, RHCE, CISSP [http://www.lesbell.com.au] Tel: +61 2 9451 1144 FreeWorldDialup: 800909

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Re: [CentOS] Ideas for stopping ssh brute force attacks
by Les Bell 23 Jul '08

23 Jul '08

Ned Slider <ned(a)unixmail.co.uk> wrote: >> I don't think anyone is suggesting running SSH on a non-standard port as a sole means of defence << I should hope not, but the point does bear making. >> We should also remember that public/private key authentication is only secure as the host the private key is stored on when keys without passphrases are employed (all too common where users don't want to trade using a password for a passphrase). << Another good point. This is why I strongly recommend the use of ssh-agent (or Pageant for those with a Windows desktop) as a mechanism for minimising the inconvenience of constant prompting for a strong key passphrase. Of course, this has to be coupled with awareness of the need to lock the workstation or unload the keys when leaving the desk. The other piece of the puzzle is agent forwarding, so that I only need to keep a private key on my workstation, even when logging in to a gateway machine and then to a server beyond it. They private key file is always under my local physical control - in fact, the truly paranoid can keep their private keys on a USB device or a smartcard. Using this approach, I can sit at my university office desk, provide a passphrase once when loading a key into the ssh agent, and then connect through firewalls to machines in my home office, with no further prompting or inconvenience and very low probability of the private key being compromised. Best, --- Les Bell, RHCE, CISSP [http://www.lesbell.com.au] Tel: +61 2 9451 1144 FreeWorldDialup: 800909

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