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1500 questions
194
votes
6 answers
how to disable SSH login with password for some users?
On Linux (Debian Squeeze) I would like to disable SSH login using password to some users (selected group or all users except root). But I do not want to disable login using certificate for them.
edit: thanks a lot for detailed answer! For some…
Stepan
- 2,159
194
votes
13 answers
Top level domain/domain suffix for private network?
At our office, we have a local area network with a purely internal DNS setup, on which clients all named as whatever.lan. I also have a VMware environment, and on the virtual-machine-only network, I name the virtual machines whatever.vm.
Currently,…
Otto
- 2,171
192
votes
10 answers
How do I verify the speed of my NIC?
I just installed a new gigabit network interface card (NIC) in Linux. How do I tell if it is really set to gigabit speeds? I see ethtool has an option to set the speed, but I can't seem to figure out how to report its current speed.
User1
- 2,556
191
votes
5 answers
I am under DDoS. What can I do?
This is a Canonical Question about DoS and DDoS mitigation.
I found a massive traffic spike on a website that I host today; I am getting thousands of connections a second and I see I'm using all 100Mbps of my available bandwidth. Nobody can…
Falcon Momot
- 25,314
191
votes
5 answers
DNS - NSLOOKUP what is the meaning of the non-authoritative answer?
For some domains nslookup gives me a Non-authoritative answer section. What does this mean?
Got answer:
HEADER:
opcode = QUERY, id = 3, rcode = NXDOMAIN
header flags: response, want recursion, recursion avail.
questions…
mahen3d
- 4,422
191
votes
10 answers
What is "-bash: !": event not found"
Try executing the following under a bash shell echo "Reboot your instance!"
On my installation:
root@domU-12-31-39-04-11-83:/usr/local/bin# bash --version
GNU bash, version 4.1.5(1)-release (i686-pc-linux-gnu)
Copyright (C) 2009 Free Software…
Maxim Veksler
- 2,805
190
votes
9 answers
Resolve host name from IP address
I'm looking for a command line tool which gets an IP address and returns the host name, for Windows.
DouglasJose
- 2,023
190
votes
6 answers
SSL Certificate Location on UNIX/Linux
Is there any standard or convention for where SSL certificates and associated private keys should go on the UNIX/Linux filesystem?
John Topley
- 2,205
190
votes
4 answers
Should I quit using Ifconfig?
With the servers that mount Infiniband cards, when I use the ifconfig command, I get this warning:
Ifconfig uses the ioctl access method to get the full address
information, which limits hardware addresses to 8 bytes.
Because Infiniband address has…
Zhen
- 2,159
190
votes
2 answers
What are the different widely used RAID levels and when should I consider them?
This is a Canonical Question about RAID levels.
What are:
the RAID levels typically used (including the RAID-Z family)?
deployments are they commonly found in?
benefits and pitfalls of each?
MDMarra
- 101,023
189
votes
12 answers
Physically locating the server
I've got a CentOS server somewhere in the building; I can login into it remotely and VNC, etc. Now I've got to physically move it, and for that I need to physically locate the machine among the lookalikes around the office.
What can I do remotely to…
Michael
- 1,723
187
votes
73 answers
What tool do you use to monitor your servers?
For a more comprehensive list of monitoring tools and their features, check out this Wikipedia page.
As the question states, what are the most commonly used tools used for this task and what are their strengths and weaknesses?
Aron Rotteveel
- 8,569
- 18
- 53
- 64
187
votes
13 answers
Why couldn't MAC addresses be used instead of IPv4|6 for networking?
I am reading up on TCP/IP and other related protocols and technologies. MAC addresses are described as being (reasonably :) unique, and as having a large possibility space (several hundred trillions), while also being assigned to all network…
Félix Saparelli
- 1,393
186
votes
6 answers
185
votes
8 answers
Filename length limits on linux?
Are there any filename or path length limits on Linux?
readonly
- 3,429