Troubleshooting Unix / Linux Servers

Troubleshooting tips about Linux, *BSD, UNIX, Apple OS X, programming and MS-Windows servers and desktop systems ( rss feed ).

I‘m a new FreeBSD Unix system user. How can I find out the process/programs names listing on a certain port on a FreeBSD Unix systems using command line? How do I lookup the process which is currently bound to the given network port on a FreeBSD server?

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My OpenSSH server listing on TCP port number 2222. How can I use ssh-copy-id with an sshd server with listing on a different port on a Linux or Unix-like systems?

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I need to tunnel X Window securely over SSH bases session so that I run X program on my remote Linux/Unix server/workstation and get back display to my Apple Macbook pro laptop. I tried the ssh -X user@server1 and ssh -Y user@server2 commands on both OS X Mountain Lion and Apple OS X Mavericks/Yosemite. But, I am unable to use the ssh command with X11.

How do I fix this problem on OS X and enable X11 forwarding with ssh command? How do I install XQuartz (X11.app) server on Apple OS X Mountain Lion or Mavericks or Yosemite?

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I‘m installing FreeBSD 10 Xorg and xfce4 desktop. But, getting the following error:

(EE) Failed to load module “fbdev” (module does not exist, 0)

How do I fix this problem on FreeBSD 10 amd64 based system?

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I am a new Linux server user. I need to tunnel X over ssh. I type the following command on a CentOS/RHEL based remote host to get display on a local desktop:

ssh -X user@server1.cyberciti.biz
xeyes &
firefox &

But, I am getting an error that read as follows:

**error**: Failed to contact configuration server; some possible causes are that you need to enable TCP/IP networking for ORBit, or you have stale NFS locks due to a system crash. See http://projects.gnome.org/gconf/ for information. (Details – 1: Failed to get connection to session: /bin/dbus-launch terminated abnormally without any error message)

How do I fix this error on a newly formatted/installed RHEL or CentOS Linux 6.x server?

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I am a new Linux server user. I need to tunnel X over ssh. I type the following command from OS X Unix terminal to login into far_away_machine (a centos server):

ssh -X -o options -A -p 22 user@centos-far-away-server

But, I am getting the following error on screen:

X11 forwarding request failed on channel 0
Last login: Sun Mar 23 15:58:51 2014 from 1.2.3.4

How do I fix “X11 forwarding request failed on channel 0″ on Linux or Unix-like systems?

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I am using a CentOS Linux v6.5 on my home server and I am getting the following error when I execute yum command:

rpmdb: PANIC: fatal region error detected; run recovery
error: db3 error(-30974) from dbenv->open: DB_RUNRECOVERY: Fatal error, run database recovery
error: cannot open Packages index using db3 – (-30974)
error: cannot open Packages database in /var/lib/rpm
CRITICAL:yum.main:

Error: rpmdb open failed

How do I fix this problem on a CentOS / RHEL based system?

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