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1500 questions
53
votes
9 answers
Why would a server not send a SYN/ACK packet in response to a SYN packet
Lately, we've become aware of a TCP connection issue that is mostly limited to mac and Linux users who browse our websites.
From the user perspective, it presents itself as a really long connection time to our websites (>11 seconds).
We've managed…
codemonkey
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53
votes
4 answers
What does the "IN" mean in a zone file?
Sometimes a record is listed as www IN A 192.168.1.1 and sometimes it is listed as www A 192.168.1.1.
What is the purpose of the IN and when is it required/not required?
Tabitha
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53
votes
11 answers
Why should I use Amazon Route 53 over my registrar's DNS servers?
I am building a site that I anticipate will have high usage. Currently, my registrar (GoDaddy) is handling DNS. However, Amazon's Route 53 looks interesting. They promise high speed and offer globally distributed DNS servers and a programmable…
Abtin Forouzandeh
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53
votes
9 answers
Determine if filesystem or partition is mounted RO or RW via Bash Script?
Is there an easy way to determine if a mounted filesystem is mounted as Read-Only or Read-Write? I was thinking just to pipe mount but I thought there might be an easier way.
Jake Wilson
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53
votes
22 answers
Why change default ssh port?
I've noticed that a lot of admins change the default ssh port.
Is there any rational reason to do so?
sheerun
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53
votes
4 answers
MySQL: creating a user that can connect from multiple hosts
I'm using MySQL and I need to create an account that can connect from either the localhost or from another server, i.e. 10.1.1.1. So I am doing:
CREATE USER 'bob'@'localhost' IDENTIFIED BY 'password123';
CREATE USER 'bob'@'10.1.1.1' IDENTIFIED BY…
DrStalker
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53
votes
5 answers
How exactly & specifically does layer 3 LACP destination address hashing work?
Based on an earlier question over a year ago (Multiplexed 1 Gbps Ethernet?), I went off and setup a new rack with a new ISP with LACP links all over the place. We need this because we have individual servers (one application, one IP) serving up…
Stu Thompson
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53
votes
4 answers
Linux command line character limit
I'm passing a variable to a script on the command line. What is the character limit of a command? eg:
$ MyScript reallyreallyreally...reallyreallyreallylongoption
Thanks.
robdog
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- 5
53
votes
7 answers
Force SSH to use a specific shell
Is there any way to force SSH to use a particular shell on the remote end, regardless of what the user's default shell is?
I've tried solutions akin to:
ssh host.domain.com /bin/bash -c 'complicated, multi-line command'
but unfortunately the…
plinehan
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53
votes
10 answers
How to Chown a directory recursively including hidden files or directories
Seems like chown with the recursive flag will not work on hidden directories or files. Is there any simple workaround for that?
toby
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53
votes
7 answers
How can I find the LDAP server in the DNS on Windows?
For Linux, this command should return the DNS record for the LDAP server
host -t srv _ldap._tcp.DOMAINNAME
(found at Authenticating from Java (Linux) to Active Directory using LDAP WITHOUT servername)
How could I get the same on the Windows command…
mjn
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53
votes
6 answers
Stop ssh client from offering all the public keys it can find?
Like most sysadmins I use openssh all the time. I have about a dozen ssh keys, I like to have a different ssh key for each host. However this causes a problem when I am connecting to a host for the first time, and all I have is a password. I want to…
Amandasaurus
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53
votes
4 answers
how to restrict access to directory and subdirs
I need to restrict access to any files or subdirs in direstory "testdir". My conf:
...
location ~* ^.+\.(jpg|txt)$ {
root /var/www/site;
}
location /testdir {
deny all;
return 404;
}
...
In my…
tst
53
votes
4 answers
How can I find out what is causing interrupts on Windows?
Occasionally I come across servers (Windows 2003 and 2008) with high processor % interrupt time. Is there a way to see what program or device is causing the interrupts?
jlupolt
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52
votes
6 answers
What are the pros and cons of having your own UPS attached to your own server hosted in a data center?
According to this comment by Tom O'Connor (slightly edited below):
You can seriously cheese off a datacentre by putting an UPS inside your own rack.
What are the risks to the data center should a customer (somehow) choose to do this?
JonathanDavidArndt
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