[BR]: nginx-http-auth filter does not match because of two subsequent timestamps from systemd-journald and nginx about fail2ban HOT 7 CLOSED

the error log can not be changed in nginx and it always adds a timestamp to the error message

Imho, it depends on how the log-forwarding to syslog in configured.

Changing the start of the expression from ^\s*[error] to ^.*[error] resolves this problem and the filter matches.

This is ugly workaround, since the RE becomes vulnerable due to broken anchor - because ^.* is quasi the same as if it were missing, so no anchor anymore and REs may match everywhere (also against a user input with an "injection" attempt), additionally it becomes very slow, especially on long messages, since it must search the whole message.

Anyway for people having that format here is interim workaround:

- mdre-auth = ^\s*\[error\] \d+#\d+: \*\d+ user "(?:[^"]+|.*?)":? (?:password mismatch|was not found in "[^\"]*"), client: <HOST>, server: \S*, request: "\S+ \S+ HTTP/\d+\.\d+", host: "\S+"(?:, referrer: "\S+")?\s*$
+ mdre-auth = ^\s*(?:(?!\[)\S+ nginx\[\d+\]: [^\[]*)?\[error\] \d+#\d+: \*\d+ user "(?:[^"]+|.*?)":? (?:password mismatch|was not found in "[^\"]*"), client: <HOST>, server: \S*, request: "\S+ \S+ HTTP/\d+\.\d+", host: "\S+"(?:, referrer: "\S+")?\s*$
- mdre-fallback = ^\s*\[crit\] \d+#\d+: \*\d+ SSL_do_handshake\(\) failed \(SSL: error:\S+(?: \S+){1,3} too (?:long|short)\)[^,]*, client: <HOST>
+ mdre-fallback = ^\s*(?:(?!\[)\S+ nginx\[\d+\]: [^\[]*)?\[crit\] \d+#\d+: \*\d+ SSL_do_handshake\(\) failed \(SSL: error:\S+(?: \S+){1,3} too (?:long|short)\)[^,]*, client: <HOST>

(part (?:(?!\[)\S+ nginx\[\d+\]: [^\[]*)? would optionally match systemd prefix with also optional additional timestamp)

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Thanks a lot for the quick resolution. I suspected that my workaround is a dirty hack.

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mdre-fallback = ^\s*(?:(?!\[)\S+ nginx\[\d+\]: [^\[]*)?\[crit\] \d+#\d+: \*\d+ SSL_do_handshake\(\) failed \(SSL: error:\S+(?: \S+){1,3} too (?:long|short)\)[^,]*, client: <HOST>

Ive apply but always same it return 228 missed... any suggestion?

Debian 11
Fail2ban 0.11.2

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People... nobody can provide any suggestions, if you give zero info.
In order to help you, we need at least one "missed" message you complain about...
Try it with:

fail2ban-regex --print-all-missed systemd-journal 'nginx-http-auth[mode=aggressive]'

and provide few lines that are still missed by filter as an example.

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f2b.txt

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It doesn't look to me that your nginx writes the error-log to systemd journal - there is no one message which should be matched by filter. I see only warnings or start emergency-messages (throwed by start of nginx-unit per worker), nothing else.

If you mean it must be really systemd journal, try to find out (with journalctl in json output) which tags it uses exactly, current filter use _SYSTEMD_UNIT=nginx.service + _COMM=nginx.
For instance:

journalctl -o json | grep nginx

(or something similar)

If not (errorlog is a file) - you must use backend = auto and set proper logpath for this jail.

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ok ok will check later, too many result with journalctl -o json | grep nginx... no time for check all now xD

Thanks for helped me!

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