lab 4 Feature/lab4

.github/pull_request_template.md

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+# Goal
+Making the lab
+# Changes
+Added submission1.md and .github/pull_request_template.md to make the lab for every tasks
+# Testing
+Checking acceptable points 

labs/submission1.md

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+# Lab 1 Submission
+
+## Task 1 — SSH Commit Signing
+
+### Benefits of Signed Commits
+Прочитав документации, можно сказть, что подпись коммитов важна, так как она позволяет проверять личность автора изменений git с помощью GPG или SSH-ключей, гарантировать, что содержимое коммита не было изменено после подписания, подтверждать, что коммит создан доверенным источником, а не злоумышленником, выполнять требования безопасности в регулируемых или open-source проектах, обнаруживать изменения
+
+### Setup Evidence
+Сгенерирован SSH ключ `~/.ssh/id_ed25519`, скриншот ключа в профиле
+![alt text](image.png)
+
+### Signed Commit
+Создан файл submission1.md и сделаны несколько коммитов при редактировании, скриншот од ного из них с комментарием
+![alt text](image-1.png)
+
+### Why Important in DevOps?
+В DevOps подпись коммитов критична для безопасности цепочки поставок (supply chain security). Она предотвращает внедрение вредоносного кода от имени других разработчиков.

labs/submission4.md

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+# Lab 4 — Operating Systems & Networking
+
+**Goal**: Analyze operating system fundamentals and conduct network diagnostics to develop core DevOps infrastructure skills.
+
+## Task 1 — Operating System Analysis
+
+### Boot Performance Analysis
+
+> systemd-analyze
+Startup finished in 1.292s (userspace) graphical.target reached after 1.272s in userspace.
+
+> systemd-analyze blame
+653ms landscape-client.service
+301ms snapd.seeded.service
+211ms snapd.service
+210ms dev-sdd.device
+140ms wsl-pro.service
+118ms snapd.socket
+108ms logrotate.service
+99ms user@1000.service
+88ms systemd-resolved.service
+80ms systemd-journal-flush.service
+69ms rsyslog.service
+59ms systemd-udev-trigger.service
+43ms systemd-timesyncd.service
+38ms systemd-udevd.service
+36ms systemd-logind.service
+34ms user-runtime-dir@1000.service
+33ms dpkg-db-backup.service
+32ms e2scrub_reap.service
+32ms dbus.service
+31ms systemd-journald.service
+
+`sysatem-analze` shows time wasted for system startup 
+`sysatem-analze blame` output list of all running services and time each one took to start
+
+### Check System Load
+
+> uptime
+10:18:21 up 12 min,  1 user,  load average: 0.00, 0.00, 0.00
+> w
+10:18:24 up 12 min,  1 user,  load average: 0.00, 0.00, 0.00
+USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU  WHAT
+dhehehe  pts/1    -                10:05   12:40   0.00s   ?    -bash
+
+`uptime` outputs current time in device, system running time since boot, logged in users count, average CPU load over 1, 5, and 15 minutes
+
+`w` shows who is logged in and what they are doing
+
+#### Key Observations:
+- **Boot time:** System boots very quickly 
+- **Slowest service:** `landscape-client.service` takes **653ms**
+- **Current uptime:** System has been running for **12 minutes** since 10:05 AM bu user dhehehe
+
+### Process Forensics
+
+> ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%mem | head -n 6
+    PID    PPID CMD                         %MEM %CPU
+    207       1 /usr/bin/python3 /usr/share  0.1  0.0   
+   1641       1 /usr/libexec/packagekitd     0.1  0.0   
+     40       1 /usr/lib/systemd/systemd-jo  0.0  0.0   
+    153       1 /usr/lib/systemd/systemd-re  0.0  0.0   
+      1       0 /usr/lib/systemd/systemd --  0.0  0.0 
+
+> ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%cpu | head -n 6
+    PID    PPID CMD                         %MEM %CPU
+      1       0 /usr/lib/systemd/systemd --  0.0  0.0   
+     89       1 /usr/lib/systemd/systemd-ud  0.0  0.0   
+   1641       1 /usr/libexec/packagekitd     0.1  0.0   
+   1054       1 /usr/lib/polkit-1/polkitd -  0.0  0.0   
+   1217       1 /usr/libexec/wsl-pro-servic  0.0  0.0 
+
+`ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%mem | head -n 6` shows processes sorted by memory usage (highest first)
+
+`ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%cpu | head -n 6` shows processes sorted by CPU usage (highest first)
+
+#### Key Observations:
+- **Overall resource usage:** All processes show *0.0-0.1%* CPU and memory 
+- **Memory leaders:** Python script (PID 207) and PackageKit (PID 1641) at 0.1% each
+- **CPU leaders:** systemd (PID 1) shows 0.0% — no active CPU consumers
+
+> The top memory-consuming process is `/usr/bin/python3` (PID 207) at 0.1% memory, tied with `packagekitd` (PID 1641).
+
+
+### Service Dependencies
+
+> systemctl list-dependencies
+> systemctl list-dependencies multi-user.target
+default.target
+○ ├─display-manager.service
+○ ├─systemd-update-utmp-runlevel.service
+○ ├─wslg.service
+● └─multi-user.target
+○   ├─apport.service
+●   ├─console-setup.service
+●   ├─cron.service
+●   ├─dbus.service
+○   ├─dmesg.service
+○   ├─e2scrub_reap.service
+○   ├─landscape-client.service
+○   ├─networkd-dispatcher.service
+●   ├─rsyslog.service
+○   ├─snapd.apparmor.service
+○   ├─snapd.autoimport.service
+○   ├─snapd.core-fixup.service
+○   ├─snapd.recovery-chooser-trigger.service
+●   ├─snapd.seeded.service
+○   ├─snapd.service
+multi-user.target
+○ ├─apport.service
+● ├─console-setup.service
+● ├─cron.service
+● ├─dbus.service
+○ ├─dmesg.service
+○ ├─e2scrub_reap.service
+○ ├─landscape-client.service
+○ ├─networkd-dispatcher.service
+● ├─rsyslog.service
+○ ├─snapd.apparmor.service
+○ ├─snapd.autoimport.service
+○ ├─snapd.core-fixup.service
+○ ├─snapd.recovery-chooser-trigger.service
+● ├─snapd.seeded.service
+○ ├─snapd.service
+● ├─systemd-ask-password-wall.path
+● ├─systemd-logind.service
+○ ├─systemd-update-utmp-runlevel.service
+● ├─systemd-user-sessions.service
+
+`systemctl list-dependencies`shows a tree of all units and their dependencies
+
+`systemctl list-dependencies multi-user.target` shows everything that needs to start to reach multi-user mode
+
+### User Sessions
+
+> who -a
+           system boot  2026-02-22 10:05
+           run-level 5  2026-02-22 10:05
+LOGIN      tty1         2026-02-22 10:05               209 id=tty1
+LOGIN      console      2026-02-22 10:05               200 id=cons
+dhehehe  - pts/1        2026-02-22 10:05 01:11         382
+
+> last -n 5
+reboot   system boot  6.6.87.2-microso Sun Feb 22 10:05   still running
+reboot   system boot  6.6.87.2-microso Wed Feb 18 12:39 - 12:42  (00:02)
+reboot   system boot  6.6.87.2-microso Wed Feb 11 14:29 - 15:37 (1+01:07)
+reboot   system boot  6.6.87.2-microso Wed Feb  4 16:06 - 13:25 (3+21:19)
+reboot   system boot  6.6.87.2-microso Wed Feb  4 15:50 - 16:06  (00:15)
+
+wtmp begins Sat Dec 20 16:09:18 2025
+
+#### Key Observations:
+- **Runlevel:** 5 
+- **Logged in user:** `dhehehe` on pts/1 since 10:05, idle for **1 hour 11 minutes**
+- **Boot history:** Most sessions are very short (2 min, 15 min) except one 3-day session
+- **Kernel version:** `6.6.87.2-microso`  Microsoft-optimized kernel for WSL
+- **Longest session:** 3 days, 21 hours from Feb 4-8
+
+### Memory Ananlysis
+
+> free -h
+               total        used        free      shared  buff/cache   available
+Mem:            15Gi       587Mi        14Gi       3.6Mi       238Mi        14Gi
+Swap:          4.0Gi          0B       4.0Gi
+
+> cat /proc/meminfo | grep -e MemTotal -e SwapTotal -e MemAvailable
+MemTotal:       16048316 kB
+MemAvailable:   15448540 kB
+SwapTotal:       4194304 kB
+
+#### Key Observations:
+- **Total RAM:** 15 GiB (approximately 16 GB)
+- **Used memory:** 587 MiB (about 3.8% of total)
+- **Available memory:** 14 GiB 
+- **Swap usage:** 4 GB swap allocated but **completely unused (0B)**
+- **Memory efficiency:** System is very lightweight with minimal memory consumption
+- **Buffers/cache:** 238 MiB used for caching 
+
+**Memory Usage Pattern:** Memory usage is extremely low, with the top processes using only 0.1% each. This suggests either a freshly booted system or one with very light workload
+
+## Task 2 — Networking Analysis
+
+### Network Path Tracing
+
+> traceroute github.com
+traceroute to github.com (140.82.121.3), 64 hops max    
+  1   172.30.208.1  0.702ms  0.181ms  0.113ms
+  2   10.91.48.1  7.046ms  3.109ms  2.702ms
+  3   10.252.6.1  3.756ms  2.559ms  3.229ms
+  4   188.170.164.34  6.608ms  7.139ms  11.476ms        
+  5   *  *  *
+  6   *  *  *
+  7   *  *  *
+  8   *  *  *
+  9   83.169.204.82  58.098ms  47.133ms  41.556ms       
+ 10   194.68.123.180  44.541ms  73.244ms  45.322ms      
+ 11   *  *  *
+ 12   *  *  * 
+ 13   *  *  * 
+ 14   *  *  * 
+ 15   94.103.180.54  59.053ms  57.009ms  56.883ms 
+ 16   94.103.180.24  55.210ms  56.990ms  54.972ms 
+ 17   45.153.82.37  59.970ms  61.112ms  56.139ms 
+ 18   *  *  * 
+ ......
+ 64   *  *  *
+
+> dig github.com
+
+; <<>> DiG 9.18.39-0ubuntu0.24.04.2-Ubuntu <<>> github.com
+;; global options: +cmd
+;; Got answer:
+;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 15449
+;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
+
+;; OPT PSEUDOSECTION:
+; EDNS: version: 0, flags:; udp: 4096
+;; QUESTION SECTION:
+;github.com.                    IN      A
+
+;; ANSWER SECTION:
+github.com.             5       IN      A       140.82.121.4
+
+;; Query time: 20 msec
+;; SERVER: 10.255.255.254#53(10.255.255.254) (UDP)      
+;; WHEN: Sun Feb 22 12:33:59 MSK 2026
+;; MSG SIZE  rcvd: 55
+#### Key Observations:
+**IP Address Mismatch**: Traceroute shows destination IP 140.82.121.3, while dig returns 140.82.121.4 — GitHub uses multiple IPs for load balancing (both in the same /24 subnet).
+
+**Geographical Latency Jump**: Latency jumps from ~11 ms (hop 4) to ~58 ms (hop 9) — a +47 ms increase indicating intercontinental transition (likely Europe → USA).
+
+**Hidden Nodes**: Asterisks on hops 5-8, 11-14, and 18-64 -  routers configured not to respond to ICMP requests (standard security practice).
+
+### Packet Capture
+> sudo timeout 10 tcpdump -c 5 -i any 'port 53' -nn
+tcpdump: data link type LINUX_SLL2
+tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
+listening on any, link-type LINUX_SLL2 (Linux cooked v2), snapshot length 262144 bytes
+
+0 packets captured
+0 packets received by filter
+0 packets dropped by kernel
+
+> dig -x 8.8.4.4
+> dig -x 1.1.2.2
+
+; <<>> DiG 9.18.39-0ubuntu0.24.04.2-Ubuntu <<>> -x 8.8.4.4
+;; global options: +cmd
+;; Got answer:
+;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 37050
+;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
+
+;; OPT PSEUDOSECTION:
+; EDNS: version: 0, flags:; udp: 4096
+;; QUESTION SECTION:
+;4.4.8.8.in-addr.arpa.          IN      PTR
+
+;; ANSWER SECTION:
+4.4.8.8.in-addr.arpa.   5020    IN      PTR     dns.google.
+
+;; Query time: 39 msec
+;; SERVER: 10.255.255.254#53(10.255.255.254) (UDP)      
+;; WHEN: Sun Feb 22 12:48:42 MSK 2026
+;; MSG SIZE  rcvd: 73
+
+
+; <<>> DiG 9.18.39-0ubuntu0.24.04.2-Ubuntu <<>> -x 1.1.2.2
+;; global options: +cmd
+;; Got answer:
+;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 20093
+;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
+
+;; OPT PSEUDOSECTION:
+; EDNS: version: 0, flags:; udp: 4096
+;; QUESTION SECTION:
+;2.2.1.1.in-addr.arpa.          IN      PTR
+
+;; AUTHORITY SECTION:
+1.in-addr.arpa.         669     IN      SOA     ns.apnic.net. read-txt-record-of-zone-first-dns-admin.apnic.net. 23597 7200 1800 604800 3600
+
+;; Query time: 306 msec
+;; SERVER: 10.255.255.254#53(10.255.255.254) (UDP)      
+;; WHEN: Sun Feb 22 12:48:42 MSK 2026
+;; MSG SIZE  rcvd: 137
+
+**DNS Server**: Local provider DNS at 10.255.255.254 handles all queries with good response times.
+**Query Types:** Standard A record query for github.com, PTR queries for reverse lookups.
+**Response Status:**
+github.com: NOERROR with A record
+8.8.4.4: NOERROR with PTR record  
+1.1.2.2: NXDOMAIN
+**Response Time Variation:**
+github.com: 20 ms
+8.8.4.4: 39 ms
+1.1.2.2: 306 ms
+
+### One example DNS query from packet capture
+> sudo timeout 15 tcpdump -c 5 -i any 'port 53' -nn
+tcpdump: data link type LINUX_SLL2
+tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
+13:28:58.590048 lo    In  IP 10.255.255.254.35297 > 10.255.255.254.53: 52971+ [1au] A? yandex.ru. (50)
+13:28:58.595934 lo    In  IP 10.255.255.254.53 > 10.255.255.254.35297: 52971 1/0/1 A 213.180.193.56 (54)
+13:28:58.619182 lo    In  IP 10.255.255.254.42813 > 10.255.255.254.53: 64820+ [1au] A? github.com. (51)
+5 packets captured
+14 packets received by filter
+