Questions tagged [troubleshooting]

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

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39 views

router or reverse proxy - network failure

I have an edgerouter x sfp as the main router to the internet. To this router a server is connected with a reverse proxy docker running called swag eg. letsencrypt which I use to access nextcloud and ...
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17 views

WVD App attach launching windows file explorer

I'm trying to virtualize some apps and test the app attach feature with MSIX packages. I've followed all the steps, and expanded the MSIX into a VHD. I've uploaded the VHD and placed it in a hostpool /...
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22 views

Remote host can be connected to via SSH but cannot connect to the Internet

I am trying to find out why a remote host with which I can connect via SSH cannot connect to the internet. When I try to ping said server, it will answer back with 1 ping and every subsequent packets ...
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2answers
247 views

Using ENV variables in Postfix and Dovecot configuration files

I'm trying to dockerize my mailing server and I'm having some troubles regarding how am I supposed to use environment variables inside Postfix and Dovecot configuration files (I'm using the latest ...
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1answer
597 views

Kubernetes: kube-dns servers are not reachable (other pods are reachable)

this is an odd one. I've setup my K8s cluster, 1 master and 1 worker. It uses calico as cni, and everything looks to be working as expected (I'm able to deploy pods, services, etc). I'm able to reach ...
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1answer
27 views

Unable to see computers on site to site VPN

Windows server: 192.168.0.10 Linux server: 192.168.0.1 Network printer: 192.168.0.30 192.168.0.0/24 site to site with 192.168.1.0/24 On a computer on second subnet (192.168.1.32) I can ping the Linux ...
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0answers
58 views

Could an incompatable Xeon processer cause only two of four RAM slots to be used?

Issue With everything installed correctly, only two of my four RAM sticks are being recognized with the BIOS. I checked the QVL for the motherboard, and the Xeon E5-2628L v3 that I am using is not ...
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26 views

All unregistered domains are being redirected to the same IP. What does this mean?

Whenever I make a request to an unregistered URL, I receive a 301 response code and I'm redirected to a specific IP. For example, in response to http GET http://dsfijewijfeif.com I get: HTTP/1.1 301 ...
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1answer
2k views

What would be causing “PowerShell.exe” to hang upon opening on multiple systems and/or how can I troubleshoot it?

What would be causing "PowerShell.exe" to hang upon opening on multiple systems? I've waited for over 60 minutes, but it never fully starts. All it does is show the blue shell window with the ...
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1answer
50 views

Troubleshooting “traps: proces_name[pid] general protection” memory issue on Linux

I'm trying to troubleshoot a memory issue on one of my servers. Some time ago a daemon my company is developing crashed with segmentation errors. All would be somewhat fine, but seconds later other ...
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26 views

How to troubleshoot internet down every day?

Every day the server is unreachable and I need to unplug and replug it in. I cannot ping it and all web services are down. After a reboot the internet is back on again. There are no cronjobs fail2ban ...
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1answer
95 views

how to man-in-the-middle blocking/intercepting/editing all network traffic going to a single cabled device and a server

I need to completely block and intercept and alter all packets going between two devices. possibly i need to isolate one device and block/intercept/edit ALL traffic going to and from it if i cannot ...
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1answer
812 views

HP ML350 G6 will not power on

I have no lights on MB or back of power supply. I have replaced power supply and added a redundant power supply. I replaced PD board or backplane whatever you want to call it. Still same result. ...
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1answer
115 views

How do I troubleshoot possible drive issues on ESXi 6.7?

I have a Dell Poweredge R630 with 4 drives in a RAID. I'm not sure if it's RAID 10 or RAID 5 because I didn't order or set up the server originally and I'm just the default network admin, it's not my ...
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1answer
33 views

Unable to start mariadb

My ubuntu server's mariadb service was down and from running "journalctl -xe" I could see that the error must be caused by courrupted files so i append the following entry to my /etc/mysql/my.cnf file ...
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1answer
957 views

Troubleshoot random server freezes without log entries

We are experiencing a very particular and unique problem on our C# application which is running under .NET framework 4.7.2, in kiosk mode on Windows 10 Operating System that runs on a Lenovo ...
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1answer
822 views

mysqldump cron job runs in terminal but not cron tab

I have this cron job, /usr/bin/mysqldump -u username -p'password' MyDatabase > /backup/CronBackup/MyDatabaseBackup.sql &>/backup/CronBackup/cronBackupLog.log I have been through this page: ...
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0answers
31 views

Diagnosing increase in traffic hitting a Django web application

This question is about diagnosing the causes of elevated network traffic in an internet-facing web application. Background: The web application in question is a Django-based forum where users upload ...
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1answer
120 views

iptables rejects vpn client by port

Here is my iptables commands: sudo iptables -F sudo iptables -A INPUT -p tcp -s 109.123.74.85 --dport 27000 -j ACCEPT sudo iptables -A INPUT -p tcp -s 188.170.80.4 --dport 27000 -j ACCEPT sudo ...
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1answer
111 views

How to troubleshoot internal DNS resolution (Windows DNS server) pointing to a local server with a static internal IP address

To better explain the set up I have a Debian server in a private network with a static IP. There is a windows AD server that resolves DNS for clients internally. A domain name is already registered ...
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1answer
459 views

nginx workers stack at 100% usage after X random days

I am facing a strange incident, under which my two nginx workers suddenly get stack at 100% of CPU usage after a random number of days and at the same web traffic, under which they are behaving fine ...
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0answers
821 views

AD domain rename problems, can't add server of the same name

I have inherited an active directory domain controller, and after adding a number of servers I found that I couldn't add a server with a specific name. I since found out the admin who built the ...
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133 views

Diagnosing NFSv4 Authentication Issues

I've got a couple of NFSv4 shares (with Kerberos authentication). Most of the time they work quite well, but when there's an issue they can be a pain to fix. I put this down to them being quite ...
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0answers
647 views

How to diagnose UDP connectivity issues?

I have an OpenVPN connection which was initially over UDP. After some time I started to have serious hiccups when running ssh inside that tunnel. As seen from inside the tunnel, ssh packets were lost,...
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1answer
76 views

How to interpret the debug output from Amavis->Spamassassin?

Could please someone explain how Spamassassin build the following strings: Oct 17 14:00:30 server amavis[29497]: (29497-02) SA dbg: uridnsbl: domain amazonaws.com in skip list, host sns.eu-central-1....
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2answers
1k views

How to determine process which makes DNS Request? [duplicate]

I have a server on AWS, GuardDuty started send me notifications: *** "type":"Backdoor:EC2/C&CActivity.B!DNS", *** {"domain":"libcurl.so","protocol":"UDP","blocked":false} *** is querying a domain ...
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1answer
35 views

Why does LAN stops working if switch is connected to two upfeeds?is [closed]

If I connect my switch to two upstream feeds from my ISP, my internal LAN stops functioning (see illustration below). What is it in the TCP/IP protocol that is disrupted to cause the above? ...
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2answers
1k views

Error: No space left on device: (deleted)/dev/zero

**** Hoster something changed on hypervizor but said, that nothing was changed. The problem is not on the server anymore... **** Could someone help me to solve the following problem: If I want to ...
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1answer
2k views

Office 365 In-Place Hold preventing me from deleting user

I am using AD Connect to synchronize my on-premises Active Directory to our Office 365 tenant. I tried disabling a user from on-premises and then synchronizing to O365. However, it seems to have ...
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0answers
37 views

Investigating night time shut downs

I have a Windows Server 2008 R2 install (AMD FX-4100 quad core, 32gb) is shutting down around 2:30 am every other night. I've updated the motherboard BIOS but that hasn't helped. I ran AUTORUNS.EXE ...
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1answer
101 views

Diagnose Sudden Slowness on Linux

I have two identical Linux laptops (Core™ i7-4810MQ with 32GB RAM) both running Ubuntu 16.04. Running seemingly any command on machine 2 takes about 4-12 times as long as on machine 1, depending on ...
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1answer
211 views

Periods of high packet loss, two ethernet cables plugged into TWC modem

A small business for which I am the system administrator has been experiencing intermittent internet dropouts. There seems to be no pattern to the dropouts — sometimes there is nothing for a week, and ...
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1answer
1k views

Strange behavior from App-V virtualized application - can't start new instance until all others are closed

I first must apologize for the vagueness of this. It is rather hard to pin down, which is why I turn to posting this. The environment is Windows 2012 R2 Citrix 7.16 servers, multi-tenant (which is ...
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1answer
836 views

Updating a Zone File - Adding CNAME records - How to troubleshoot/where have I gone wrong?

I apologize in advance for this newbie question. I've resorted to asking because I can't seem to find enough closely-related queries* on this network or elsewhere, and the BIND 9.9 ARM is not exactly ...
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1answer
443 views

SSRS Subscription fails, Server Response 4.4.1

I have an SSRS server that processes many subscriptions on a daily basis. I have just become aware of this, so I don't know if it is a new or an old problem, but only one subscription has been ...
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1answer
159 views

How to diagnose end user DNS problems with my domain? [closed]

I work for a small part of a large organization that has been on the internet since dinosaur days (pre-CIDR). I'm confident our DNS is properly configured, but a tiny fraction (<1%) of our remote ...
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1answer
668 views

What to do with trailing slash in $HOME on CentOS?

I have a little project server sandbox running CentOS. Setting up a new server package, I realized I needed to add new directory to the path and I found $HOME has a trailing slash for the main user. ...
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1answer
584 views

Cisco C220 M3 Doesn't Recognize HBA, SSD

I am attempting to set up a Cisco C220 M3 blade server for a company and have been running into issues with the hard driver controller(s) that the machine has. The intent is to have vmWare ESXi ...
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2answers
485 views

Part of LAN network connected to 1 switch freezes up periodically

I'm managing an office network which is spread across 2 buildings. (see network setup below) In building 2, we are getting a problem where the network slows down and then completely cuts off. The ...
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0answers
687 views

How can I test network connectivity to a Keberos KDC (UDP/88)

How can I test network connectivity to a Keberos KDC (UDP/88)? Does Kerberos have a standard way to communicate that gives any output? HTTP for example, nc -v google.com 80 GET will dump the ...
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1answer
10k views

How to troubleshoot Nginx 499 when it's not returning a web sockets handshake back to the client?

In a Kubernetes cluster, I have an Nginx server acting like a reverse proxy / TLS termination solution that proxypass requests to a backend Tomcat application that has some functionalities powered by ...
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3answers
173 views

How to investigate critical server load reported by nagios3? [closed]

Nagios3 running on my Ubuntu Server occasionally sends me email reports similar to: Notification Type: PROBLEM Service: Current Load Host: localhost Address: 127.0.0.1 State: CRITICAL Date/Time: ...
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2answers
2k views

Cannot ping any Windows device on local network, but can ping *nix

Strange issue started yesterday: I cannot ping any Windows PC on my local network. I have (2) Windows 7 Pro devices, one of which was reimaged just before this issue started; (1) Windows 10 Education ...
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0answers
227 views

Troubleshoot random Network disconnection (USB Modem)

In general how to debug random network disconnection issues? I am working on Intel edison board which is connected to the internet via a Huawei E8231 USB Modem. Few devices loose the internet ...
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1answer
130 views

Tomcat view connector settings being used

Is there a way to view what settings are set for a connector at runtime? For instance, I want to see what maxConnections is set to. Pretty much verify all these settings: https://tomcat.apache.org/...
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0answers
145 views

What network setting could impact iperf3 results?

I am making some bandwidth tests to set a baseline for some other tests and I have a behaviour I cannot understand. The tests are done with iperf3 on Linux (with and without -R to get both up- and ...
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0answers
239 views

How to troubleshoot rx_tcp_udp_chksum_err

Recently our Nagios started reported network interface errors on few servers and I have no idea how to identify what caused these errors. I collected some information here and hope someone can ...
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0answers
303 views

Ubuntu 14.04 becomes unresponsive after 2-12 hours + of idle time

As the title says my Ubuntu 14.04 server becomes unresponsive after a period of being idle. It is going to be an NGNX proxy box, but not taking production traffic yet for obvious reasons. It ran for ...
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1answer
563 views

OpenVpn troubleshooting

I run a VPN with Openvpn on a Debian 8 server. It works kinda well. Sometimes (once a month or every 3 weveks) the tunnel stops running and I have to reboot the server to be able to connect to the ...
0
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1answer
152 views

Diagnosing why apache virtual host has stopped working

We have an Apache (IBM HTTP Server that is a fork of Apache: http://www-03.ibm.com/software/products/en/http-servers) server that runs virtual hosts that listen to port 80, 8000, and others (this for ...

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