106 lines
5.2 KiB
Plaintext
106 lines
5.2 KiB
Plaintext
# Fail2Ban filter for openssh
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#
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# If you want to protect OpenSSH from being bruteforced by password
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# authentication then get public key authentication working before disabling
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# PasswordAuthentication in sshd_config.
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#
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#
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# "Connection from <HOST> port \d+" requires LogLevel VERBOSE in sshd_config
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#
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[INCLUDES]
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# Read common prefixes. If any customizations available -- read them from
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# common.local
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before = common.conf
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[DEFAULT]
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_daemon = sshd
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# optional prefix (logged from several ssh versions) like "error: ", "error: PAM: " or "fatal: "
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__pref = (?:(?:error|fatal): (?:PAM: )?)?
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# optional suffix (logged from several ssh versions) like " [preauth]"
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__suff = (?: \[preauth\])?\s*
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__on_port_opt = (?: port \d+)?(?: on \S+(?: port \d+)?)?
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# for all possible (also future) forms of "no matching (cipher|mac|MAC|compression method|key exchange method|host key type) found",
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# see ssherr.c for all possible SSH_ERR_..._ALG_MATCH errors.
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__alg_match = (?:(?:\w+ (?!found\b)){0,2}\w+)
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[Definition]
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prefregex = ^<F-MLFID>%(__prefix_line)s</F-MLFID>%(__pref)s<F-CONTENT>.+</F-CONTENT>$
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cmnfailre = ^[aA]uthentication (?:failure|error|failed) for <F-USER>.*</F-USER> from <HOST>( via \S+)?\s*%(__suff)s$
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^User not known to the underlying authentication module for <F-USER>.*</F-USER> from <HOST>\s*%(__suff)s$
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^Failed \S+ for invalid user <F-USER>(?P<cond_user>\S+)|(?:(?! from ).)*?</F-USER> from <HOST>%(__on_port_opt)s(?: ssh\d*)?(?(cond_user): |(?:(?:(?! from ).)*)$)
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^Failed \b(?!publickey)\S+ for (?P<cond_inv>invalid user )?<F-USER>(?P<cond_user>\S+)|(?(cond_inv)(?:(?! from ).)*?|[^:]+)</F-USER> from <HOST>%(__on_port_opt)s(?: ssh\d*)?(?(cond_user): |(?:(?:(?! from ).)*)$)
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^<F-USER>ROOT</F-USER> LOGIN REFUSED.* FROM <HOST>\s*%(__suff)s$
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^[iI](?:llegal|nvalid) user <F-USER>.*?</F-USER> from <HOST>%(__on_port_opt)s\s*$
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^User <F-USER>.+</F-USER> from <HOST> not allowed because not listed in AllowUsers\s*%(__suff)s$
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^User <F-USER>.+</F-USER> from <HOST> not allowed because listed in DenyUsers\s*%(__suff)s$
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^User <F-USER>.+</F-USER> from <HOST> not allowed because not in any group\s*%(__suff)s$
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^refused connect from \S+ \(<HOST>\)\s*%(__suff)s$
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^Received <F-MLFFORGET>disconnect</F-MLFFORGET> from <HOST>%(__on_port_opt)s:\s*3: .*: Auth fail%(__suff)s$
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^User <F-USER>.+</F-USER> from <HOST> not allowed because a group is listed in DenyGroups\s*%(__suff)s$
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^User <F-USER>.+</F-USER> from <HOST> not allowed because none of user's groups are listed in AllowGroups\s*%(__suff)s$
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^pam_unix\(sshd:auth\):\s+authentication failure;\s*logname=\S*\s*uid=\d*\s*euid=\d*\s*tty=\S*\s*ruser=<F-USER>\S*</F-USER>\s*rhost=<HOST>\s.*%(__suff)s$
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^(error: )?maximum authentication attempts exceeded for <F-USER>.*</F-USER> from <HOST>%(__on_port_opt)s(?: ssh\d*)?%(__suff)s$
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^User <F-USER>.+</F-USER> not allowed because account is locked%(__suff)s
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^<F-MLFFORGET>Disconnecting</F-MLFFORGET>: Too many authentication failures(?: for <F-USER>.+?</F-USER>)?%(__suff)s
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^<F-NOFAIL>Received <F-MLFFORGET>disconnect</F-MLFFORGET></F-NOFAIL> from <HOST>: 11:
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^<F-NOFAIL>Connection <F-MLFFORGET>closed</F-MLFFORGET></F-NOFAIL> by <HOST>%(__suff)s$
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^<F-MLFFORGET><F-NOFAIL>Accepted publickey</F-NOFAIL></F-MLFFORGET> for \S+ from <HOST>(?:\s|$)
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mdre-normal =
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mdre-ddos = ^Did not receive identification string from <HOST>%(__suff)s$
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^Connection <F-MLFFORGET>reset</F-MLFFORGET> by <HOST>%(__on_port_opt)s%(__suff)s
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^<F-NOFAIL>SSH: Server;Ltype:</F-NOFAIL> (?:Authname|Version|Kex);Remote: <HOST>-\d+;[A-Z]\w+:
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^Read from socket failed: Connection <F-MLFFORGET>reset</F-MLFFORGET> by peer%(__suff)s
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mdre-extra = ^Received <F-MLFFORGET>disconnect</F-MLFFORGET> from <HOST>%(__on_port_opt)s:\s*14: No supported authentication methods available%(__suff)s$
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^Unable to negotiate with <HOST>%(__on_port_opt)s: no matching <__alg_match> found.
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^Unable to negotiate a <__alg_match>%(__suff)s$
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^no matching <__alg_match> found:
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mdre-aggressive = %(mdre-ddos)s
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%(mdre-extra)s
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cfooterre = ^<F-NOFAIL>Connection from</F-NOFAIL> <HOST>
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failregex = %(cmnfailre)s
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<mdre-<mode>>
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%(cfooterre)s
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# Parameter "mode": normal (default), ddos, extra or aggressive (combines all)
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# Usage example (for jail.local):
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# [sshd]
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# mode = extra
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# # or another jail (rewrite filter parameters of jail):
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# [sshd-aggressive]
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# filter = sshd[mode=aggressive]
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#
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mode = normal
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#filter = sshd[mode=aggressive]
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ignoreregex =
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maxlines = 1
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journalmatch = _SYSTEMD_UNIT=sshd.service + _COMM=sshd
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datepattern = {^LN-BEG}
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# DEV Notes:
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#
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# "Failed \S+ for .*? from <HOST>..." failregex uses non-greedy catch-all because
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# it is coming before use of <HOST> which is not hard-anchored at the end as well,
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# and later catch-all's could contain user-provided input, which need to be greedily
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# matched away first.
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#
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# Author: Cyril Jaquier, Yaroslav Halchenko, Petr Voralek, Daniel Black and Sergey Brester aka sebres
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# Rewritten using prefregex (and introduced "mode" parameter) by Serg G. Brester.
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