Finding problems in a program and trying to solve these.

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29
votes
5answers
10k views

Debugger for Iptables

I'm looking for an easy way to follow a packet through the iptables rules. This is not so much about logging, because I don't want to log all traffic (and I only want to have LOG targets for very few ...
15
votes
8answers
11k views

How to setup a fake SMTP server to catch all mails?

I'm looking for an smtp service that essentially obeys the RFC, except rather than sending mail it simply logs to a file [date] sent mail to <address> Or whatever. I can bash this together ...
12
votes
3answers
24k views

Debugging rules in Iptables [duplicate]

Possible Duplicate: Debugger for Iptables Hi, How can I know how many packets were dropped by my iptables rules ?? Is there any debugging mechanism to see which rule is Dropping my packet ...
12
votes
1answer
586 views

ext4 listing of files very slow in one specific directory that contained lots of files before

Background I had a small logrotate misshap... Logrotate would rotate the archived logs by misstake causing a quadratic growth of files in my /var/log/. And by the time I caught wind that something ...
12
votes
2answers
3k views

Kernel stack trace to source code lines

Given a kernel stack trace as below, how do you determine the specific line of code where the issue occurred? kernel: [<ffffffff80009a14>] __link_path_walk+0x173/0xfb9 kernel: ...
10
votes
12answers
579 views

What's the first thing you check when an untouched unix server starts going berserk?

So you have this neatly setup unix server and it's super fast and works swell and everything is great for months, and suddenly all kinds of weird errors start showing up for a variety of different ...
8
votes
7answers
5k views

Equivalent of SysInternals FileMon for Linux?

I'm attempting to debug an application on Ubuntu - I need to listen to file open attempts (even for files that don't exist). Process Monitor (formerly known as FileMon) is available on Windows - ...
8
votes
3answers
1k 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 ...
7
votes
4answers
10k views

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?
6
votes
4answers
747 views

How to pinpoint which process/activity/software/protocol is slowing down LAN on a single computer

From this question about debugging our business LAN I've been able to pinpoint a single computer which slows down our network. When the computer is turned on and connected to the network, roughly 5% ...
5
votes
0answers
692 views

How to configure PHPStorm to debug on IIS

I installed PHP 5 on IIS on a Windows 7 64 bit machine using the Web Platform Installer. I am using PHPStorm as my PHP IDE but cant find any documentation on how to get debugging to work. PHPStorm ...
4
votes
3answers
4k views

How can I find out where a file is physically located on the disk (block numbers)?

This is an obscure question, I know. I'm trying to do some performance testing of some disks on a Linux box. I'm getting some inconsistent results, running the same test on the same disk. I know ...
4
votes
2answers
6k views

Why would brk() in strace output be taking several seconds?

We've been noticing a significant slowdown of one of our applications when migrated to Ubuntu Hardy, amd64. It runs perfectly well on Debian Sarge i386. Running an 'strace -r' against the (Apache ...
4
votes
4answers
9k views

How can I investigate sustained high CPU usage by Microsoft.Exchange.Rpc.ClientAccess.Service.exe?

One CAS server in our array has nearly 90% of its 4 CPUs used. The remaining CAS servers are at 30 percent. How should I investigate what is causing this increase? Below is a graph of: Six ...
4
votes
2answers
5k views

How to enable debug of dhcp client on Windows 7

Is it possible to enable some sort of debugging for dhcp client on Windows 7?
4
votes
2answers
8k views

How to debug “HTTP request sent, awaiting response”?

I have a Linux server on an ADSL connection, and I just noticed that sometimes I get Connecting to example.com|xxx.xxx.xxx.122|:80... connected. HTTP request sent, awaiting response... when I use ...
4
votes
3answers
586 views

Send bash -x output to logfile without interupting standard output

Is there a way to send the information displayed by running a bash script with the -x option to a file, while not changing the standard output seen by a user running the script? This is a debugging ...
4
votes
1answer
273 views

Crash dump analysis

I hope this isn't a stupid question, and if it is, then I want to at least get it over with so I don't feel so dumb in the future. Here we are, loading up a Windows crash dump with Windbg. Here are ...
4
votes
2answers
2k views

How to trace Apache 301 Moved Permanently?

I have one virtual host on my machine, which I am accessing localy. I am running apache2 under windows 7. When accessing this host, I see in Fiddler, that server redirects browser to different remote ...
3
votes
1answer
1k views

Why can't openSSL verify google's certificate?

When I run the command openssl -connect www.google.com:443 from a Debian VM, I get the following within the output: Verify return code: 20 (unable to get local issuer certificate) What's going ...
3
votes
4answers
3k views

Failed Request Tracing XML fails to display in Internet Explorer (IIS 7.5)

I have installed the Tracing feature and enabled failed request tracing for a website, to debug a Classic ASP website. The XML logs are created upon occurring errors, however when I open them in IE, ...
3
votes
1answer
1k views

Describing `strace` command output

I have php process which could not finish for more then 2 days. root 26511 0.0 1.6 407788 27684 ? Ss Jul09 0:08 /usr/bin/php action.php This is the output from the strace command: ...
3
votes
3answers
152 views

Are there any risks to enabling SQL Debugging

In our current environment, developers are not allowed to use SQL Debugging against any of the QA servers. It's not clear to me why the decision was made. What factors should be considered to decide ...
3
votes
3answers
1k views

Identifying “Lock Timeout” errors on SQL Server 2000

Our ERP software uses a SQL Server 2000 database. When we run a specific task on the software that used to take few seconds, a 300 seconds delay happens and SQL Server returns the error "Lock Timeout. ...
3
votes
2answers
52 views

debugger in bash

I use sh -xv my_script.sh to debug the /bin/sh script. How do I debug /bin/bash scripts? I am getting the following error and I need to know the line that needs to edit. # ./batch_master.sh ...
3
votes
2answers
8k views

All connections from this network get stuck in SYN_RECV state, connections from my home or phone properly get ESTABLISHED

My server (a linode VPS) suddenly started to timeout on every request yesterday. I'm pretty inexperienced in networking and would love to learn a process for debugging these connectivity issues. ...
3
votes
1answer
110 views

Investigating a potential CPU failure

On a Ubuntu server that I am using for computations I have recently observed that some CPU extensive programs (GUROBI,CPLEX) often segfault. Being in correspondence with tech support of the ...
3
votes
2answers
570 views

How do I figure out what is changing the userWorkstations attribute in Active Directory?

I just took over the IT for a medium sized business with a three domain controllers (2003/2008 Standard) and whenever I create a new user, after some time the user account cannot log into most ...
3
votes
1answer
283 views

Windbg: Can't get next object after a Free object

I know that fragmentation typically occurs when an object collected by garbage collection is marked as a "free" block, but the object occupying the next address space is pinned. I can get a list of ...
3
votes
1answer
195 views

Windows 2003 r2 reboots after a few seconds from initiated

I'm having troubles with a virtual machine on a ESXi running windows server 2003 r2. The problem is that every time it initiates and displays the login window, the machine reboots with no warnings, no ...
3
votes
1answer
686 views

SQL Server Debugging: “Unable to Step. Invalid operation”

I'm debugging a call to a Stored Procedure in SSMS (2012). Frequently, and various random points in the code, a dialog pops up: Microsoft SQL Server Management Studio: Unable to Step. Invalid ...
2
votes
2answers
72 views

How to obtain last bash error

I am working with a terrible project. It uses a lot of messy shell script in background. Script might include some other scripts. And many error outputs were redirected to /dev/null. When a script is ...
2
votes
2answers
275 views

sshd immediately core dumps after fsck repair

I have a centos server that recently needed a fsck repair on it's main hard drive. After fixing a bunch of inode issues (booting from a system rescue disk), the box booted clean. Most of the ...
2
votes
2answers
130 views

View headers of HTML requests to apache

Is there a good way of viewing a detailed version of incoming requests to apache? At the minimum I'd like to check for the existence of a specific header and check its value. Requests are not coming ...
2
votes
1answer
1k views

Apache 403 after configuring varnish

I just don't know where else to look and what else to do. I keep getting a 403 error on all my vhosts after setting varnish 3.0 Apacher log: [error] [client 127.0.0.1] client denied by server ...
2
votes
1answer
2k views

centos 6 debuginfo repository does not have httpd debug version available

I am trying to get the debug version of httpd so I can use it in conjunction with gdb. I am having a hard time getting them, and they don't seem to be in the standard epel-debuginfo repository. What ...
2
votes
2answers
886 views

How to intercept socket traffic on solaris?

I'm not very familiar with Solaris, so maybe there are tools that I don't know about. I need to debug the communication between two components on the same machine, talking to each other using a normal ...
2
votes
1answer
281 views

Format Filename for Process Core Files per Session

Is there a way to change the core filename format per session instead of for the entire machine? On Linux the only way I can find is using sysctl as root: sudo /sbin/sysctl -w ...
2
votes
1answer
4k views

iis 7 worker process memory leaks / hangs

From my diagnosis the worker process stops responding randomly, the server becomes very slow with 100% cpu utilization. I'm not certain but I think its because of w3wp.exe process which is my app ...
2
votes
1answer
1k views

How do you disable Just-in-Time debugging messages?

In a relatively new installation of Windows Server 2008 R2, there are occasional popup messages about Just-in-time debugging. These may come up in w3wp.exe when a search bot accesses an aspx ...
2
votes
1answer
1k views

Failure to obtain IP with ARP over Wi-Fi with personal Wi-Fi router in client mode

I'm trying to connect a Samsung TV to the Internet using a TL-MR3020 personal wireless router in client mode. The TV fails to connect to the network. It sees the ethernet cable connected though. ...
2
votes
1answer
5k views

Debug 500 Internal Server Error on IIS

Might be a n00b question. I have an IIS server with a site where I can host our website. But if I host the same website as an application in an existing site, it gives us a 500 error. But my ...
2
votes
2answers
1k views

Debugging Windows 2008 (Roaming Profile) user logon

I would appreciate some help debugging my windows 2008 profile service. Any domain account that logs on to my 2008 machine gets a +- 20 second waiting time on "user profile service" I am using ...
2
votes
1answer
312 views

flowchart for debugging a slow/unresponsive server

So the server is slow: Roll back to the previous known working build - Success? Code problem - Fail? Go on. Ping ip address - Success? maybe a DNS problem, go on. - Fail? Server or connection ...
2
votes
1answer
1k views

How to debug a website while running IIS 7?

I am running iis7 on my windows machine for testing purposes. Now I need to have access to the debugger so when something happens I can walk through it. Yet when I put debug lines on my site nothing ...
2
votes
2answers
378 views

Cisco 2811 debug command

Is there a command that allows the debugs to be shown in color. It would be easier for my techs to read the debug outputs. Didn't see any that I could find. Thanks
2
votes
0answers
498 views

How to debug CGI over fcgiwrap/nginx

I serve executable scripts (mainly in C) through fcgiwrap connected with nginx. Since the scripts are complied, I can get the coding errors during compilation, but sometimes I receive CGI errors ...
2
votes
1answer
2k views

How to debug Node + Socket.io CPU Issues

We are running a Node Socket.io server with Express 3. The server is monitored using Forever. The service is running well, but the CPU grows throughout the day, until it reaches 90%+ and then suddenly ...
2
votes
0answers
297 views

A tool to measure overhead of establishing TCP connections

I need a tool which would while doing port forwarding measure how much time was spent establishing TCP connections vs total time passed. Charles debugging proxy has the port forwarding feature and ...
1
vote
3answers
7k views

How do I identify slow queries in sql server?

I've found long, complicated instructions like this when googling for the answer to this question, an brief reference links such as in this post. I'm looking for a succinct a procedure as possible to ...