Sad Servers

This repository is a collection of troubleshooting notes for server issues encountered in real-world scenarios. It serves as a reference for developers and system administrators facing similar challenges.

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Notes

#	Title	Tags
1	"Tukaani": XZ LZMA Library Compromised	Shared Library
2	"Belo-Horizonte": A Java Enigma	Java, Swapping
3	"Florence": Database Migration Hell	Database, Migration, Nginx
4	"Constanta": Jumping Frog	CTF, Hack, newgrp, SSH
5	"Roseau": Hack a Web Server	Hack, Web Server
6	Batumi: Troubleshoot "A" cannot connect to "B"	iptables, Postgres, Systemd
7	"Karakorum": WTFIT – What The Fun Is This?	File Access Control, Web Server
8	Kihei: Surely Not Another Disk Space Scenario	Disk, strace, LVM
9	"Jakarta": it's always DNS	DNS, Name Service Switch
10	"Pokhara": SSH and other sshenanigans	SSH, User Account
11	"Monaco": Disappearing Trick	Environment Variable, Hack, Git
12	"Depok": Nginx with Brotli	Nginx, Compression
13	"Moyogalpa": Security Snag. The Trials of Mary and John	SSL, DNS, AppArmor
14	Bangalore: Envoy Panics	Envoy, Health Check, Forward Proxy, Panic Mode
15	"Minneapolis with a Vengeance": Break a CSV file	CSV, Data Processing, Scripting, Min Heap
16	Lisbon: etcd SSL cert troubles	etcd, SSL, iptables
17	Tarifa: Between Two Seas	Container, HAProxy, Nginx, Load Balancing
18	Melbourne: WSGI with Gunicorn	Nginx, Gunicorn, HTTP Header
19	Warsaw: Prometheus can't scrape the webserver	Prometheus, Metric, HTTP Method
20	Atrani: Modify a SQlite3 Database	SQlite, Database, SQL
21	"Singara": Docker and Kubernetes web app not working.	Kubernetes, k3s, Node Port Range
22	Bengaluru: Kubernetes StatefulSet least known characteristic	Kubernetes, At Most Once sematic of StatefulSet
23	Helsingør: The first walls of postgres physical replication	Postgres, Container, Replica
24	Buenos Aires: Kubernetes Pod Crashing	Kubernetes, Role Based Access Control
25	"Bern": Docker web container can't connect to db container.	Container, DNS
26	Salta: Docker container won't start.	Container, Publishing ports
27	Manhattan: can't write data into database	Disk, Systemd, Postgres, Database
28	Tokyo: can't serve web file	iptables, File Permissions
29	Cape Town: Borked Nginx	Nginx, Max Open File Descriptor Limits
30	"Hong-Kong": can't write data into database.	Disk, Database, Postgres
31	Bilbao: Basic Kubernetes Problems	Kubernetes, Scheduling
32	"Ivujivik": Parlez-vous Français?	SQL, Data Processing, CSV
33	Bucharest: Connecting to Postgres	Postgres, Database
34	"Manado": How much do you press?	Compression
35	Geneva: Renew an SSL Certificate	SSL, Reverse Proxy
36	Taipei: Come a-knocking	Port Knocking
37	Tokamachi: Troubleshooting a Named Pipe	Named Pipe, File Locking
38	Gitega: Find the Bad Git Commit	Git
39	Saint John: what is writing to this log file?	List Of Open File
40	Oaxaca: Close an Open File	List Of Open File
41	Saskatoon: counting IPs	Data Processing
42	Hanoi: Find the Multitasking Users	Bash
43	Marrakech: Word Histogram	Bash
44	"Bekasi": Supervisor is still around	Environment Variable
45	Apia: Needle in a Haystack	Diff, Checksum
46	Paris: Where is my webserver?	Hack
47	Yokohama: Linux Users Working Together	Bash, Append-Only File
48	Lhasa: Easy Math	Scripting
49	Unimak Island: Fun with Mr Jason	json, Data Processing
50	Bata: Find in /proc	Data Processing
51	Minneapolis: Break a CSV file	CSV, Data Processing
52	Venice: Am I in a container?	Container
53	Saint Paul: Merge Many CSVs files	CSV, Data Processing
54	"Rosario": Restore a MySQL database	MySQL, Database, Backup
55	"Abaokoro": Restore MySQL Databases Spooked by a Ghost	MySQL, Database, Backup
56	"Chennai": Pull a Rabbit from a Hat	RabbitMQ, Environment Variables, Access Control
57	Bharuch: "Lost in Translation"	Container, CPU Architecture, Emulator
58	"Quito": Control One Container from Another	Container, Mount
59	"Budapest": User Creation	Bash
60	"Tokelau": Delete from history	Bash
61	"Zaragoza": Test changing critical files	Mount
62	"Fukuoka": Forbidden Association	Nginx
63	"Poznań": Helm Chart Issue in Kubernetes	Helm, Kubernetes
64	"Bizerte": The Slow Application	Performance, Redis, Cache
65	"Ruaka": Kubernetes pod in distress	Kubernetes, Helm
66	"Campina Grande": Give me my cert, Vault	Hashicorp Vault, PKI
67	Kampot: "A New Port"	Nginx
68	"Kampala": Strange Script Error	Dos2Unix
69	"Bondo: Split my pile!	Disk, Inode
70	"Atlantis": Not found	Multi-Stage Build, C library
71	"Amygdala": Do you have enough insight to see the secrets?	Kubernetes, Vault