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Which networked services are already running?

There are multiple networked services running on your VM right now. To output the networked services running on the VM use netstat (install using apt).

  • Question 1a: What command did you use to display the networked services? netstat -p (I'm not very sure because I can't understand very well what is "networked services")

  • Question 1b: Paste the output of the command. Active Internet connections (w/o servers)

Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp6       0      0 10.0.2.15:ssh           _gateway:64390          ESTABLISHED 1354/sshd: lucus [p
udp        0      0 ubuntu1:bootpc          _gateway:bootps         ESTABLISHED 757/NetworkManager
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags       Type       State         I-Node   PID/Program name     Path
unix  3      [ ]         STREAM     CONNECTED     30231    1457/dbus-daemon     /run/user/126/at-spi/bus
unix  3      [ ]         STREAM     CONNECTED     27268    1374/pipewire-pulse
...

  • Question 1c: Choose one service from the output and describe what it does. sshd: providing secure remote access to another system over a network. NetworkManager: providing network configuration and management for Linux-based operating systems.

  • Question 2a: What is the systemctl command to show whether bind9 is running or not? systemctl status bind9

  • Question 2b: Why does the dig command (dig ocf.berkeley.edu) work if @localhost is not present at the end (if bind9 is not started) but times out when @localhost is added? Because with "@localhost" the dig send the request to the specified localhost DNS server (in this case bind9) but the bind9(Berkeley Internet Name Domain) has been closed so the command eventually times out. Without "@localhost" it will send the request to other DNS may have the response.

  • Question 2c: What additional entries did you add to your DNS server config (the db.example.com file)?

;
; BIND data file example.com
;
$TTL    604800
@       IN      SOA     ns.example.com. root.example.com. (
                                1                     ; Serial
                                604800          ; Refresh
                                86400             ; Retry
                                2419200         ; Expire
                                604800 )        ; Negative Cache TTL
;
        IN      NS      ns.example.com.

ns  IN  A   127.0.0.1                ; IP for name server (random ip)
@   IN      A       1.2.3.4          ; A record for example.com (random ip)
test IN A 93.184.216.34
@ IN AAAA 2001:0db8:85a3:0000:0000:8a2e:0370:7334
@ IN MX 10 mail.example.com
; Add more records (Ex. CNAME, AAAA, MX, subdomains...)

";" means ignore by the DNS server this is for human to read "@" means the main the domain "example.com"

  • Question 2d: What commands did you use to make requests to the local DNS server for your additional entries? dig @localhost example.com AAAA

  • Question 3a: Do you notice any pattern when you refresh the page multiple times? Hi, I am ID x

  • Question 3b: What load balancing algorithm are you using? roundrobin and leastconn

  • Question 3c: What did you add to the haproxy config? (just copy and paste the lines you added to the bottom into here)

listen stats
  bind    0.0.0.0:7001
  mode    http
  stats   enable
  stats   hide-version
  stats   uri /stats

frontend my_frontend
bind 127.0.0.1:7000
default_backend my_backend

backend my_backend
balance leastconn
default-server check maxconn 5
server server0 127.0.0.1:8080
server server1 127.0.0.1:8081
server server2 127.0.0.1:8082
server server3 127.0.0.1:8083
server server4 127.0.0.1:8084
server server5 127.0.0.1:8085

  • Question 3d: What do you notice has changed on the stats page after adding health checks? What color are each of the servers in the backend now? before: ![[Screenshot 2024-02-02 at 11.13.12 pm.png]] after:![[Screenshot 2024-02-02 at 11.13.52 pm.png]]

  • Question 3e: What changes in the stats page when you crash a worker? What happened to the pattern from before? ![[Pasted image 20240202231705.png]]

  • Question 3f: What HTTP status code (or error message) does HAProxy return if you crash all of the workers? 503 Service Unavailable No server is available to handle this request.