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Linux / Unix Command To Find Out NFS Clients Connected To My NFS Server

How do I find out how many nfs clients are connected to NFS server running on Red Hat Enterprise Linux?
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Reload Squid Proxy Server Without Restarting Squid Daemon

I made some changes to the /etc/squid/squid.conf file and issued the command /sbin/service squid restart. However, this command takes way too much time to restart the server. How do I tell squid to just reread the config file and apply new changes under Linux operating systems?
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Slow DNS on Linux with IPv4 and IPV6 Configured Firewall

I'm getting slow DNS response from ssh and other network related traffic with delay of 30-60+ seconds per connection. All of our servers are behind hardware based dedicated firewall. My RHEL v6.1 server system running on HP hardware. How do I fix this problem?
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No xauth Program; Cannot Forward With Spoofing Error and Solution

I want to use my local machine as the X server over ssh. But when I try to run ssh -X -v user@server1.example.com to the remote machine, I get the following error:

debug1: Remote: No xauth program; cannot forward with spoofing

How do I fix this problem and use X over ssh?
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Linux: Iptables Find / Check Banned IP Address

How do I find or check IP's that are currently banned using iptables command in Linux? How do I verify that IP address is banned or not in Linux?
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Solaris UNIX: Display LUNs

How do I display LUNs under Solaris UNIX version 10 or earlier?
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Linux Disable Shell / FTP Access For a User Account

My users will only be checking mail, and I want to disable FTP access as well as shell access under CentOS Linux. How do I disable shell (SSH) and FTP access to a new or old user under Linux without deleting user account?
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What Is The Difference Between Authentication And Authorization?

What is the difference between authentication and authorization? Why it is important to understand difference between the two? Authentication vs. Authorization -- what are they and how do they differ?
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SSH Authentication refused: bad ownership or modes for file /home/user/.ssh/authorized_keys2

I'm trying to login using ssh keys but server is only allows to login me using a password. The following message is logged into server /var/log/secure file:

Feb 25 06:36:50 ns5 sshd[26681]: Authentication refused: bad ownership or modes for file /home/user/.ssh/authorized_keys2

How do I fix this problem?
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Best Method To Reboot Remote Linux / Windows / UNIX Server

Q. I've couple of Linux / Windows server hosted in remote data center? My ISP provides following option for rebooting the box:
a) Graceful shutdown command
b) An IPMI reboot
c) A power strip

Which one is the best way to reboot server and why?
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