Troubleshooting is a form of problem solving, often applied to repair failed products or processes.

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WHEN does IIS 6.0 Application Pool CRASH with memory issues?

We've been having Out of Memory issues with our mixed classic ASP/.NET site for quite some time. Basically, we see a couple of different cases: Some request (SQL query that returns a LARGE ...
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304 views

Cisco 878 Router Physical Layer troubleshooting

My problem: Upon connecting the FastEthernet0 with a straight-through cable to a Catalyst switch, the line protocol comes up briefly and then goes down. Interface goes down too, I now have this on my ...
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279 views

How to troubleshoot intermittent winsock 10054 errors on Windows Server 2003 SP2

We are getting 10054 errors in a couple of our applications on one server running Windows Server 2003 SP2. This happens intermittently, and we also have other similar servers running the same ...
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4k views

What factors can disrupt a VSAT connection?

In some locations, the only option for an internet connection is to use some form of Satellite dish. Like any wireless medium these can be quite tricky to troubleshoot. What factors have you ...
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163 views

What sort of network problems can a single NIC host cause?

A remote office has a Cisco ASA 5505 connecting the LAN to our HQ LAN via VPN. When a particular Windows XP PC is connected to the ASA via a switch, the VPN tunnel drops, and after a short while, all ...
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652 views

Can't update SQL Server 2008 to SP3, it only offers the option to create a new instance

A colleague is attempting to update our server's SQL Server 2008 version 10.0.1600.22 (not R2) install up to SP3. Unfortunately, we can't work out where the "Update" button is; the installer seems to ...
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636 views

Slow connection to a shared .mdb file over a LAN on some machines only

A single client program on each of about 10 computers are sharing a .mdb file on a windows 7 machine. The network is cabled and has a switch. For no obvious reason the connection on 2 of these ...
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289 views

Application getting VERY slow only in the morning: tools to track the culprit?

I have two Ubuntu Servers: one acting as db server (mysql) and file server and the application server. Using this three service an application has been working flawlessly for months. Now we've found ...
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620 views

How to check http errors with Windows 2008 Server?

This is the best I can describe my problem... I am running a search engine scraper essentially on Windows 2008 Server. Constantly accessing millions of random domain names and following their links ...
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260 views

how do I troubleshoot rdp

I have one Windows XP SP3 pc on the domain that I cannot rdp into. The xp pc is enabled for rdp sessions. Port 3389 is open in the firewall. There are no errors in the event logs. I have tried to rdp ...
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1answer
77 views

When troubleshooting a complex issue is there a reason to go with an additive vs subtractive troubleshooting methodology

TLDR: I am interested in finding out whether there is a reason to select an additive approach to troubleshooting over a subtractive approach, or vice-versa when trying to troubleshoot a problem with ...
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79 views

Internal e-mails

We need to send mails from our domain (assume this is example.com) to our self. Now, the 'incoming' mails are handled by another server (from Google). We can send mails through sendmail to external ...
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2k views

Putty + Bash + Screen, up arrow for history not working (Ubuntu 11.10)

I have a fresh install of Ubuntu Server 11.10 that I am logging into SSH via PuTTy. When I am inside screen, I cannot use the up arrow to recall bash history (though this works outside of screen). I ...
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210 views

How to troubleshoot many failed pageloads?

I've had a few cases in which the homepage of one of my sites wouldn't load in the browser. The site is running on django/fastcgi/nginx. It was difficult to reproduce so, in an attempt to understand ...
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1answer
186 views

Troubleshooting potential compromised server from Brute Force SSH Attack [duplicate]

Possible Duplicate: My server's been hacked EMERGENCY So I noticed some files/folders on my webserver and investigating leads the fact that a brute force attack via SSH was done on my ...
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111 views

nginx redirecting for no reason?

This was really annoying and now i see when it happens. If <ip>/NAME exist in /var/www (/var/www/NAME) nginx will give me a redirect to www._.com/NAME/ (note the slash and lack of url) which is ...
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758 views

Trying to bridge NIC. What does this error mean?

I would like to bridge between br0 and tap0 for my OpenVPN server, but I get the error at the bottom of this post. Background The server have one physical eth0 with IP xxx.xxx.68.58. The bridge ...
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887 views

Troubleshooting Nagios alerts; aka. Why aren't my alerts firing?

I'm attempting to add email alerts to an existing Nagios install. I've been using the web interface to keep an eye on some non-critical systems for a few months and it's been running well; warnings ...
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3answers
146 views

Ubuntu 10.04 install is missing /etc/rc0.d, is there a quickfix?

I have no idea how this happened, but /etc/rc.*/ is simply missing. As a result, aptitude and apt-get don't work right anymore. Is there a quick-fix for this? I really don't want to reinstall the OS ...
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2k views

Performing root-cause analysis

I want to learn more about how to perform root-cause analysis. More times than not, our department tells the user to try rebooting (thier Windows XP system), which actually "fixes" a good number of ...
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1answer
138 views

Proxy-Connection Header associated with failed connections

I work with microprocessor devices that have/run a micro webserver. I have two of these devices set up so that they can be accessible to/by the Internet - I'll call the devices "A" and "B". ...
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1answer
198 views

End-user SSL certificate management workflow

We have an internal website, served from behind HTTPS with client certificates. Website users are non-technical persons, working remotely. They use Windows (XP, Vista, 7) and OS X (10.5, 10.6, 10.7). ...
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343 views

Ubuntu troubleshooting

I have a computer which keeps becoming unreachable, and a restart fixes the problem. It's under somewhat heavy load (high cpu, and high ram usage), but appears for the most part stable. What's a good ...
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2answers
969 views

Server is rebooting unexpectedly, strange kernel messages in log file

I have a server running Ubuntu 10.04 that is rebooting several times a day it seems, and I can't figure out why. It doesn't appear to be a graceful reboot either, because some of the services complain ...
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SSH closes connection when key is accepted

In server's auth.log: Failed publickey for agladysh from MYIP port 61313 ssh2 In ssh -vvv: debug1: Offering public key: /Users/agladysh/.ssh/id_rsa debug3: send_pubkey_test debug2: we sent a ...
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77 views

LAN - troubleshooting

I have 2 clients on my LAN that I'm trying to get to "see" each other. The first as follows Computer1 IP 172.21.62.230 Subnet 255.255.255.224 Default gateway 172.21.62.225 Preferred DNS server ...
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652 views

Troubleshooting firewall and routing on Linux

Are there any tools or API hooks for troubleshooting iptables or routing on Linux? (besides the obvious -j LOG) In other words: what to do when tables with 200 or 300 firewalling rules after adding a ...
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227 views

VMWare Workstation connection problems

Our old setup (which worked): On workstation W-1 (WinXP - 64bit) we had two virtual machines (VMWare 6.5) V-1 and V-2 (both with WinXP-32). All of them had a different IP static address, V-1 and ...
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5k views

Troubleshooting linux server reboots?

I have a Linux server I've just set up, debian squeeze, 2.6.32-5-amd64, and over the past week it's rebooted three times, twice in one day. There was no power outage that I am aware of (and it's ...
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2answers
250 views

my ssh sessions are randomly killed on Debian

I have a Debian 6.0.1 vanilla install, and I use PUTTY to ssh into it. I will usually have 3 or 4 PUTTY login shells running at the same time. What I'll find is that if I leave my computer for a ...
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539 views

High ping everywhere except one PC

I have a network with a really high ping (usually more than 500ms) except for one laptop. And in that laptop the ping is usually 5ms. I've tried: - using same model laptop - compare lan driver ...
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51 views

Troubleshoot DBMail in SQL Server 2005

On a SQL Server 2005 machine, I have DBMail setup and correctly configured. I am able to use "Notify Operator" and EXEC msdb.dbo.sp_send_dbmail to queue emails. But the problem is the queued mails ...
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117 views

troubleshooting a printer problem

I have a large Kyocera Printer/Scanner/Copier machine in a office with three PCs (all plugged into a lan via router. The three PCs all have individual printers (inkJets) hooked directly via printer ...
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ADFS 2.0 Errors Event ID 184 & 364

I have ADFS servers set up and each component such as in URN, relay, claims etc. in place, but am getting this error massage "There was a problem accessing the site. Try to browse to the site ...
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1answer
1k views

Maximum amount of memory per session with IIS/.NET

I'm troubleshooting some memory issues we're running into with a heavily used ASP.NET site hosted on IIS6. Intermittently we have to manually recycle our application pool (process) to resolve issues ...
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2answers
3k views

Cannot mount /dev/sdc1 on Debian 5.0, special device /dev/sdc1 doesn't exist

I'm trying to fix an odd problem I'm having that I've never seen or heard of before. I have a disk, /dev/sdc and I'm trying to mount it, but cannot. sudo mount /dev/sdc1 /mnt mount: you must ...
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1answer
812 views

Port forwarding not working, tcpdump shows “reset connection”

I have an home web server that I use to serve a few pages for personal purposes. The server runs Ubuntu and is behind an ADSL connection, and it's working nicely. Recently I subscribed to a Hiperlan ...
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681 views

How can you identify why a Windows service (TeamCity build agent) is hanging when running a command?

I've got a problem with a Windows service I just simply can't get to the bottom of. What I'm trying to do is execute the HP WebInspect 9.0 application from a TeamCity build agent which runs as a ...
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1answer
244 views

mac OS X version 10.6.5 network connection troubleshooting/solution?

Im connected to a small office network where where everything works fine. however once in a while or on a random occasion usually after the computer has been left on or on sleep all night there are ...
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1answer
264 views

DHeapmon not reporting expected number of total desktops in IIS6

Hope someone can help me make sense of this. I'm trying to debug some COM+ errors we see in our production environment and a few of them report that the desktop heap is exhausted, so I installed ...
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107 views

DNS oddities with different nameservers

My ISP's DNS servers are sometimes sketchy, so I use 4.2.2.1 and 8.8.8.8 respectively. The Layer 3 DNS server and Google's DNS server. Sometimes there will be a long delay in resolving, and if I ...
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645 views

COM+/Desktop Heap errors in IIS affecting sites at random?

We have a Win2K3 server that is hosting 30+ sites. Each site is configured to have its own unique application pool -- so that we can manually recycle specific sites if needed and not kill sessions ...
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1answer
382 views

How do I troubleshoot network connectivity problems in windows?

I'd really like to understand how to debug my network connectivity issues, but everything I find on the internet is either for basic users on "How to add a wireless network" or it's people talking ...
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1answer
4k views

What causes the issue (possibly packet loss) in this scenario

I'm trying to diagnose a network related problem - please understand these points before suggesting an answer (apologies if more information is required, I will add anything people ask). We have a ...
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785 views

Random Ubuntu server network disconnects

After installing Ubuntu Server 10.04.1 on a new x86_64 kvm instance (Debian 6.0 hosted) I'm getting -apparently- ramdon disconnects from the server. Read from remote host myserver: Connection ...
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Open ports broken from internal network [duplicate]

Quick summary: Forwarded port works from the outside world, but from the internal network using the external IP the connection is refused. This is a simplified situation to make the explanation ...
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28k views

page allocation failure - am I running out of memory?

Lately I've noticing entries like this one in the kern.log of one of my servers: Feb 16 00:24:05 aramis kernel: swapper: page allocation failure. order:0, mode:0x20 This is what I'd like to know: ...
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2k views

Troubleshooting PXE Boot in CentOS

I am working on troubleshooting a PXE server that we have setup for use. It is based upon Cent OS 5.5. We installed the following components on top of a relatively vanilla install of Cent OS: ...
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3answers
103 views

Resources on Java for Sys Admins? [closed]

I've been fortunate enough to make it four years as an SA without having to administer systems making use of Java. My luck has run up and I am starting a new job and they make extensive use of Java. ...
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705 views

How to analyze which virtual host account is most greedy?

Hi there and sorry if this is too noobish. I've tried to find the answer myself as I usually do but I failed. What is the best practice when I need to analyze which virtual hosts are consuming the ...