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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

4 6

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)

1 0

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

2 1

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

1 0

Printer recommendations
by Ron Loftin 22 Jul '08

22 Jul '08

Since my old Epson C86 has finally managed to clog up the print heads, I'm in the market for a replacement. I'd like to know what the people on this list are using for printers that are currently available, since we are using versions of CUPS and foomatic that are frozen, and any other issues or "gotchas" that you are aware of. For the replacement printer, I'm considering a color laser printer instead of the inkjets that I've been using, and I'm dithering back and forth over the question of direct-connect or networked printer. Suggestions, warnings, and horror stories are welcome. Thanks in advance. -- Ron Loftin reloftin(a)twcny.rr.com "God, root, what is difference ?" Piter from UserFriendly

7 6

screen detatch
by David Mackintosh 22 Jul '08

22 Jul '08

The man page for screen says that I can create a detatched screen running with a set command in it by doing this: $ screen -dm $command However, it doesn't work. Screen exits without creating the detached screen. If I say $ screen $command ...I get dropped into a screen session running $command as I would expect. What's the magic invocation I'm missing? Also, the next step will be for root to launch said screen session as someone else during boot time; am I asking for trouble by trying it? # su - user -c screen -dmS $Label $command Thanks for any insights or pointers to web resources I can use to learn from. -- /\oo/\ / /()\ \ David Mackintosh | dave(a)xdroop.com | http://www.xdroop.com

4 4

extending 'ProxyTimeout'
by Craig White 22 Jul '08

22 Jul '08

CentOS 5 Using Proxy BalanceMember... <Proxy balancer://mongrel_cluster> BalancerMember http://localhost:3000 BalancerMember http://localhost:3001 BalancerMember http://localhost:3002 </Proxy> and I am having problems with a particular process taking longer than 2 minutes at which point the proxy seems to time out and I get an error. I added: 'ProxyTimeout 600' to the end of httpd.conf but that doesn't seem to have any impact (yes, I restarted httpd) and I'm still timing out in about 2 minutes. Any suggestions? Craig

2 2

harddisc or nfs based install
by Joseph L. Casale 22 Jul '08

22 Jul '08

When choosing either of these methods and using an iso, how does CentOS determine the right iso file to mount? Is there an expected file name format? Thanks! jlc

4 5

Oracle apps form server issue with Piranha Load balancer
by lingu 22 Jul '08

22 Jul '08

Hi all, First of all sorry for writing such a big mail.I am facing problem while implementing Piranha Load balancer on CENTOS 4 for my two oracle 11i application server running on linux. Oracle Real server details Instance Name - test url's - 1 . dev.xxx.com:8004 2 . uat.xxx.com:8004 Architecture - Services installed on dev are 1. Database Server 2.Concurrent Processing Server 3. Administration Server 4. Forms Server 5. Web server And services installed on uat are 1.Web server 2.Form server Note: Form server running on port 9004 on both hosts. Piranha details eth0 192.168.23.2 --- external physical ip eth0:1 192.168.23.3 ---EXTERNAL VIP eth2 192.168.17.125 --internal physical ip eth2:1 192.168.17.121 --INTERNAL VIP Client Network: 192.168.23.0/24 Real Server Network: 192.168.17.0/24 Client are accessing oracle application using VIP of piranha by http://192.168.23.3:8004/ Real server ips, hostname and gateway 192.168.17.16 dev.xxx.com having gateway of piranha Internal vip 192.168.17.121 192.168.17.17 uat.xxx.com having gateway of piranha Internal vip 192.168.17.121 my ipvsadm rule is like below 192.168.23.3:8004 ---->>192.168.17.16:8004 192.168.23.3:8004 ---->>192.168.17.17:8004 For me load balancing is working fine for http://192.168.23.3:8004/ . But once i logged in when ever i tried to browse any Oracle Application Forms then it is giving me error "Failed to connect to the server" uat. xxx.com:9004 Note: Form server running on port 9004 on my both oracle application sever when ever i click on any forms it is trying to connect to uat.xxx.com[which is aliased to the VIP of piranha that is 192.168.23.3 in my client host entry] so it is clearly trying to connect to 192.168.23.3:9004 but there is no service or ipvsadm rule on that vip of piranha for that 9004 port. Note: Telnet to Form server on both oracle apps server is working on 9004 from piranha server. So i created the ipvsadm rules on piranha on same vip on 9004 port like below. 192.168.23.3:9004 ---->>192.168.17.16:9004 192.168.23.3:9004 ---->>192.168.17.17:9004 But i am getting below error on my syslog ################################################################################ Jul 21 20:25:38 testlvs nanny[5064]: starting LVS client monitor for 192.168.23.3:9004 Jul 21 20:25:38 testlvs nanny[5065]: starting LVS client monitor for 192.168.23.3:9004 Jul 21 20:25:43 testlvs pulse[5040]: gratuitous lvs arps finished Jul 21 20:25:47 testlvs nanny[5065]: READ from 192.168.17.16:9004 was too short Jul 21 20:25:47 testlvs nanny[5064]: READ from 192.168.17.17:9004 was too short Jul 21 20:25:53 testlvs nanny[5061]: making 192.168.17.16:8004 available Jul 21 20:25:53 testlvs nanny[5065]: READ from 192.168.17.16:9004 was too short Jul 21 20:25:53 testlvs nanny[5059]: making 192.168.17.124:80 available Jul 21 20:25:53 testlvs nanny[5062]: making 192.168.17.17:8004 available Jul 21 20:25:53 testlvs nanny[5064]: READ from 192.168.17.17:9004 was too short Jul 21 20:25:59 testlvs nanny[5065]: READ from 192.168.17.16:9004 was too short Jul 21 20:25:59 testlvs nanny[5064]: READ from 192.168.17.17:9004 was too short Jul 21 20:26:05 testlvs nanny[5065]: READ from 192.168.17.16:9004 was too short Jul 21 20:26:05 testlvs nanny[5064]: READ from 192.168.17.17:9004 was too short Jul 21 20:26:11 testlvs nanny[5065]: READ from 192.168.17.16:9004 was too short Jul 21 20:26:11 testlvs nanny[5064]: READ from 192.168.17.17:9004 was too short Jul 21 20:26:17 testlvs nanny[5065]: READ from 192.168.17.16:9004 was too short Jul 21 20:26:17 testlvs nanny[5064]: READ from 192.168.17.17:9004 was too short Jul 21 20:26:23 testlvs nanny[5065]: READ from 192.168.17.16:9004 was too short ################################################################################ I am not able to see any thing for 9004 whenever i try ipvsdam -L. So i need some one help to solve this issue,i am facing problem only with forms rest of all of my other apps are working fine under piranha.Also forms are working fine whenever i bypassed piranha server. Regards, lingu

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