# Sample file for assignment Z5.3 (course VPS and Linux server administration)
# Server "web1" (Debian 13), login with keys only, fail2ban with maxretry = 5, findtime = 10m, bantime = 1h.
# Output of: sudo journalctl -u ssh --since "2026-11-08 03:00" --until "2026-11-08 09:00"
# and then: sudo fail2ban-client status sshd (at 09:00). All addresses are documentation addresses.

nov 08 03:12:01 web1 sshd-session[1201]: Invalid user admin from 203.0.113.77 port 40112
nov 08 03:12:01 web1 sshd-session[1201]: Connection closed by invalid user admin 203.0.113.77 port 40112 [preauth]
nov 08 03:12:19 web1 sshd-session[1204]: Invalid user oracle from 203.0.113.77 port 40398
nov 08 03:12:19 web1 sshd-session[1204]: Connection closed by invalid user oracle 203.0.113.77 port 40398 [preauth]
nov 08 03:12:40 web1 sshd-session[1210]: Invalid user test from 203.0.113.77 port 40731
nov 08 03:12:40 web1 sshd-session[1210]: Connection closed by invalid user test 203.0.113.77 port 40731 [preauth]
nov 08 03:13:02 web1 sshd-session[1215]: Invalid user ubuntu from 203.0.113.77 port 41020
nov 08 03:13:02 web1 sshd-session[1215]: Connection closed by invalid user ubuntu 203.0.113.77 port 41020 [preauth]
nov 08 03:13:25 web1 sshd-session[1221]: Invalid user postgres from 203.0.113.77 port 41377
nov 08 03:13:25 web1 sshd-session[1221]: Connection closed by invalid user postgres 203.0.113.77 port 41377 [preauth]
nov 08 03:40:12 web1 sshd-session[1302]: Invalid user admin from 198.51.100.140 port 52210
nov 08 03:40:12 web1 sshd-session[1302]: Connection closed by invalid user admin 198.51.100.140 port 52210 [preauth]
nov 08 04:05:44 web1 sshd-session[1350]: Invalid user admin from 198.51.100.140 port 52918
nov 08 04:05:44 web1 sshd-session[1350]: Connection closed by invalid user admin 198.51.100.140 port 52918 [preauth]
nov 08 04:31:09 web1 sshd-session[1399]: Invalid user admin from 198.51.100.140 port 53604
nov 08 04:31:09 web1 sshd-session[1399]: Connection closed by invalid user admin 198.51.100.140 port 53604 [preauth]
nov 08 04:56:30 web1 sshd-session[1441]: Invalid user admin from 198.51.100.140 port 54280
nov 08 04:56:30 web1 sshd-session[1441]: Connection closed by invalid user admin 198.51.100.140 port 54280 [preauth]
nov 08 05:21:58 web1 sshd-session[1490]: Invalid user admin from 198.51.100.140 port 55007
nov 08 05:21:58 web1 sshd-session[1490]: Connection closed by invalid user admin 198.51.100.140 port 55007 [preauth]
nov 08 05:47:21 web1 sshd-session[1532]: Invalid user admin from 198.51.100.140 port 55689
nov 08 05:47:21 web1 sshd-session[1532]: Connection closed by invalid user admin 198.51.100.140 port 55689 [preauth]
nov 08 06:58:03 web1 sshd-session[1604]: Connection closed by authenticating user root 198.51.100.7 port 61002 [preauth]
nov 08 08:31:47 web1 sshd-session[1688]: Accepted publickey for anna from 192.0.2.55 port 50122 ssh2: ED25519 SHA256:q3Vb0Yx8cXk2pR7mW1sTnH4dJ9eLfA6uZ5oGiC2vBQs
nov 08 08:31:47 web1 sshd-session[1688]: pam_unix(sshd:session): session opened for user anna(uid=1000) by anna(uid=0)

anna@web1:~$ sudo fail2ban-client status sshd
Status for the jail: sshd
|- Filter
|  |- Currently failed: 1
|  |- Total failed:     11
|  `- Journal matches:  _SYSTEMD_UNIT=ssh.service + _COMM=sshd
`- Actions
   |- Currently banned: 0
   |- Total banned:     1
   `- Banned IP list:

anna@web1:~$ sudo grep -E "Ban|Unban" /var/log/fail2ban.log | tail -n 2
2026-11-08 03:13:26,004 fail2ban.actions        [811]: NOTICE  [sshd] Ban 203.0.113.77
2026-11-08 04:13:26,117 fail2ban.actions        [811]: NOTICE  [sshd] Unban 203.0.113.77

Questions:
1. Which address tried the most different usernames?
2. Which address logged in successfully, and as which user?
3. Which address was banned, and at what time (hh:mm)?
4. Which address made more than five failed attempts but was not banned?
5. Why was that address not banned?
   a. The address was in ignoreip
   b. The attempts were more than ten minutes (findtime) apart, so there were never five within ten minutes
   c. fail2ban was off between 03:40 and 06:00
   d. Attempts with the name admin do not count