Verify fail2ban setup on U24

[laeti-tia]

It seems the fail2ban setup we have is not being activated for Ubuntu 24. jail.local is not copied to the /etc/fail2ban/. We also have the following warnings showing up at installation time:

Setting up fail2ban (1.0.2-3) ...
/usr/lib/python3/dist-packages/fail2ban/tests/fail2banregextestcase.py:224: SyntaxWarning: invalid escape sequence '\s'
  "1490349000 test failed.dns.ch", "^\s*test <F-ID>\S+</F-ID>"
/usr/lib/python3/dist-packages/fail2ban/tests/fail2banregextestcase.py:435: SyntaxWarning: invalid escape sequence '\S'
  '^'+prefix+'<F-ID>User <F-USER>\S+</F-USER></F-ID> not allowed\n'
/usr/lib/python3/dist-packages/fail2ban/tests/fail2banregextestcase.py:443: SyntaxWarning: invalid escape sequence '\S'
  '^'+prefix+'User <F-USER>\S+</F-USER> not allowed\n'
/usr/lib/python3/dist-packages/fail2ban/tests/fail2banregextestcase.py:444: SyntaxWarning: invalid escape sequence '\d'
  '^'+prefix+'Received disconnect from <F-ID><ADDR> port \d+</F-ID>'
/usr/lib/python3/dist-packages/fail2ban/tests/fail2banregextestcase.py:451: SyntaxWarning: invalid escape sequence '\s'
  _test_variants('common', prefix="\s*\S+ sshd\[<F-MLFID>\d+</F-MLFID>\]:\s+")
/usr/lib/python3/dist-packages/fail2ban/tests/fail2banregextestcase.py:537: SyntaxWarning: invalid escape sequence '\['
  'common[prefregex="^svc\[<F-MLFID>\d+</F-MLFID>\] connect <F-CONTENT>.+</F-CONTENT>$"'
/usr/lib/python3/dist-packages/fail2ban/tests/servertestcase.py:1375: SyntaxWarning: invalid escape sequence '\s'
  "`{ nft -a list chain inet f2b-table f2b-chain | grep -oP '@addr-set-j-w-nft-mp\s+.*\s+\Khandle\s+(\d+)$'; } | while read -r hdl; do`",
/usr/lib/python3/dist-packages/fail2ban/tests/servertestcase.py:1378: SyntaxWarning: invalid escape sequence '\s'
  "`{ nft -a list chain inet f2b-table f2b-chain | grep -oP '@addr6-set-j-w-nft-mp\s+.*\s+\Khandle\s+(\d+)$'; } | while read -r hdl; do`",
/usr/lib/python3/dist-packages/fail2ban/tests/servertestcase.py:1421: SyntaxWarning: invalid escape sequence '\s'
  "`{ nft -a list chain inet f2b-table f2b-chain | grep -oP '@addr-set-j-w-nft-ap\s+.*\s+\Khandle\s+(\d+)$'; } | while read -r hdl; do`",
/usr/lib/python3/dist-packages/fail2ban/tests/servertestcase.py:1424: SyntaxWarning: invalid escape sequence '\s'
  "`{ nft -a list chain inet f2b-table f2b-chain | grep -oP '@addr6-set-j-w-nft-ap\s+.*\s+\Khandle\s+(\d+)$'; } | while read -r hdl; do`",
Created symlink /etc/systemd/system/multi-user.target.wants/fail2ban.service → /usr/lib/systemd/system/fail2ban.service.

and this when trying to startup the service:

2024-06-18T16:28:32.591580+00:00 psu24 systemd[1]: Started fail2ban.service - Fail2Ban Service.
2024-06-18T16:28:32.724886+00:00 psu24 fail2ban-server[21860]: 2024-06-18 16:28:32,723 fail2ban.configreader   [21860]: WARNING 'allowipv6' not defined in 'Definition'. Using default one: 'auto'
2024-06-18T16:28:32.745787+00:00 psu24 fail2ban-server[21860]: 2024-06-18 16:28:32,745 fail2ban                [21860]: ERROR   No module named 'asynchat'
2024-06-18T16:28:32.768414+00:00 psu24 systemd[1]: fail2ban.service: Main process exited, code=exited, status=255/EXCEPTION

[laeti-tia]

A new installation on U24 keeps the same warning messages as above but seems to be good wrt service status:

laeti@psu24:)~-⚧ sudo systemctl status fail2ban
● fail2ban.service - Fail2Ban Service
     Loaded: loaded (/usr/lib/systemd/system/fail2ban.service; enabled; preset: enabled)
     Active: active (running) since Wed 2024-09-25 16:10:00 UTC; 4min 13s ago
       Docs: man:fail2ban(1)
   Main PID: 25251 (fail2ban-server)
      Tasks: 5 (limit: 28832)
     Memory: 18.7M (peak: 19.2M)
        CPU: 753ms
     CGroup: /system.slice/fail2ban.service
             └─25251 /usr/bin/python3 /usr/bin/fail2ban-server -xf start

Sep 25 16:10:00 psu24 systemd[1]: Started fail2ban.service - Fail2Ban Service.
Sep 25 16:10:00 psu24 fail2ban-server[25251]: 2024-09-25 16:10:00,775 fail2ban.configreader   [25251]: WARNING 'allowipv6' not defined in 'Definition'. Using default one: 'auto'
Sep 25 16:10:01 psu24 fail2ban-server[25251]: Server ready
laeti@psu24:)~-⚧ sudo fail2ban-client status
Status
|- Number of jail:	1
`- Jail list:	sshd
laeti@psu24:)~-⚧ sudo fail2ban-client set sshd banip 172.17.0.2 127.0.0.1
2
laeti@psu24:)~-⚧ sudo fail2ban-client status sshd
Status for the jail: sshd
|- Filter
|  |- Currently failed:	0
|  |- Total failed:	0
|  `- Journal matches:	_SYSTEMD_UNIT=sshd.service + _COMM=sshd
`- Actions
   |- Currently banned:	2
   |- Total banned:	2
   `- Banned IP list:	172.17.0.2 127.0.0.1