security/py-fail2ban: Add support for sshd-session

Now that sshd has been split into sshd and sshd-session, sshd-session
is now the producer of syslog messages. We cannot replace the existing
*sshd.conf files because this port must also run on older systems with
older OpenSSH. Therefore we add new filters to support both.

Reported by:	sef (private email)
MFH:		2025Q1
This commit is contained in:
Cy Schubert 2025-03-27 08:44:16 -07:00
parent d2fbfa68af
commit c98813ccb0
3 changed files with 187 additions and 1 deletions

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@ -1,6 +1,6 @@
PORTNAME= fail2ban
DISTVERSION= 1.1.0
PORTREVISION= 1
PORTREVISION= 2
CATEGORIES= security python
PKGNAMEPREFIX= ${PYTHON_PKGNAMEPREFIX}

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@ -0,0 +1,44 @@
--- bsd-sshd-session.conf.orig 2025-03-27 08:35:58.483811000 -0700
+++ bsd-sshd-session.conf 2025-03-27 08:41:34.639425000 -0700
@@ -0,0 +1,41 @@
+# Fail2Ban configuration file
+#
+# Author: Cyril Jaquier
+#
+# $Revision: 663 $
+#
+
+[INCLUDES]
+
+# Read common prefixes. If any customizations available -- read them from
+# common.local
+before = common.conf
+
+
+[Definition]
+
+_daemon = sshd-session
+
+# Option: failregex
+# Notes.: regex to match the password failures messages in the logfile. The
+# host must be matched by a group named "host". The tag "<HOST>" can
+# be used for standard IP/hostname matching and is only an alias for
+# (?:::f{4,6}:)?(?P<host>\S+)
+# Values: TEXT
+#
+failregex = ^%(__prefix_line)s(?:error: PAM: )?[A|a]uthentication (?:failure|error) for .* from <HOST>\s*$
+ ^%(__prefix_line)sDid not receive identification string from <HOST>$
+ ^%(__prefix_line)sFailed [-/\w]+ for .* from <HOST>(?: port \d*)?(?: ssh\d*)?$
+ ^%(__prefix_line)sROOT LOGIN REFUSED.* FROM <HOST>\s*$
+ ^%(__prefix_line)s[iI](?:llegal|nvalid) user .* from <HOST>\s*$
+ ^%(__prefix_line)s[iI](?:llegal|nvalid) user .* from <HOST> port \d*$
+ ^%(__prefix_line)sUser \S+ from <HOST> not allowed because not listed in AllowUsers$
+ ^%(__prefix_line)sauthentication failure; logname=\S* uid=\S* euid=\S* tty=\S* ruser=\S* rhost=<HOST>(?:\s+user=.*)?\s*$
+ ^%(__prefix_line)srefused connect from \S+ \(<HOST>\)\s*$
+ ^%(__prefix_line)sreverse mapping checking getaddrinfo for .* \[<HOST>\] .* POSSIBLE BREAK-IN ATTEMPT!$
+
+# Option: ignoreregex
+# Notes.: regex to ignore. If this regex matches, the line is ignored.
+# Values: TEXT
+#
+ignoreregex =

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@ -0,0 +1,142 @@
--- sshd-session.conf.orig 2025-03-27 08:42:15.550403000 -0700
+++ sshd-session.conf 2025-03-27 08:42:34.056893000 -0700
@@ -0,0 +1,139 @@
+# Fail2Ban filter for openssh
+#
+# If you want to protect OpenSSH from being bruteforced by password
+# authentication then get public key authentication working before disabling
+# PasswordAuthentication in sshd_config.
+#
+#
+# "Connection from <HOST> port \d+" requires LogLevel VERBOSE in sshd_config
+#
+
+[INCLUDES]
+
+# Read common prefixes. If any customizations available -- read them from
+# common.local
+before = common.conf
+
+[DEFAULT]
+
+_daemon = sshd-session
+
+# optional prefix (logged from several ssh versions) like "error: ", "error: PAM: " or "fatal: "
+__pref = (?:(?:error|fatal): (?:PAM: )?)?
+# optional suffix (logged from several ssh versions) like " [preauth]"
+#__suff = (?: port \d+)?(?: \[preauth\])?\s*
+__suff = (?: (?:port \d+|on \S+|\[preauth\])){0,3}\s*
+__on_port_opt = (?: (?:port \d+|on \S+)){0,2}
+# close by authenticating user (don't use <HOST> after %(__authng_user)s because of catch-all `.*?`):
+__authng_user = (?: (?:by|from))?(?: (?:invalid|authenticating) user <F-USER>\S+|.*?</F-USER>)?(?: from)?
+
+# for all possible (also future) forms of "no matching (cipher|mac|MAC|compression method|key exchange method|host key type) found",
+# see ssherr.c for all possible SSH_ERR_..._ALG_MATCH errors.
+__alg_match = (?:(?:\w+ (?!found\b)){0,2}\w+)
+
+# PAM authentication mechanism, can be overridden, e. g. `filter = sshd[__pam_auth='pam_ldap']`:
+__pam_auth = pam_[a-z]+
+
+[Definition]
+
+prefregex = ^<F-MLFID>%(__prefix_line)s</F-MLFID>%(__pref)s<F-CONTENT>.+</F-CONTENT>$
+
+cmnfailre = ^[aA]uthentication (?:failure|error|failed) for <F-USER>.*?</F-USER> (?:from )?<HOST>( via \S+)?%(__suff)s$
+ ^User not known to the underlying authentication module for <F-USER>.*?</F-USER> (?:from )?<HOST>%(__suff)s$
+ <cmnfailre-failed-pub-<publickey>>
+ ^Failed <cmnfailed> 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 ).)*)$)
+ ^<F-USER>ROOT</F-USER> LOGIN REFUSED FROM <HOST>
+ ^[iI](?:llegal|nvalid) user <F-USER>.*?</F-USER> (?:from )?<HOST>%(__suff)s$
+ ^User <F-USER>\S+|.*?</F-USER> (?:from )?<HOST> not allowed because not listed in AllowUsers%(__suff)s$
+ ^User <F-USER>\S+|.*?</F-USER> (?:from )?<HOST> not allowed because listed in DenyUsers%(__suff)s$
+ ^User <F-USER>\S+|.*?</F-USER> (?:from )?<HOST> not allowed because not in any group%(__suff)s$
+ ^refused connect from \S+ \(<HOST>\)
+ ^Received <F-MLFFORGET>disconnect</F-MLFFORGET> from <HOST>%(__on_port_opt)s:\s*3: .*: Auth fail%(__suff)s$
+ ^User <F-USER>\S+|.*?</F-USER> (?:from )?<HOST> not allowed because a group is listed in DenyGroups%(__suff)s$
+ ^User <F-USER>\S+|.*?</F-USER> (?:from )?<HOST> not allowed because none of user's groups are listed in AllowGroups%(__suff)s$
+ ^<F-NOFAIL>%(__pam_auth)s\(sshd:auth\):\s+authentication failure;</F-NOFAIL>(?:\s+(?:(?:logname|e?uid|tty)=\S*)){0,4}\s+ruser=<F-ALT_USER>\S*</F-ALT_USER>\s+rhost=<HOST>(?:\s+user=<F-USER>\S*</F-USER>)?%(__suff)s$
+ ^maximum authentication attempts exceeded for (?:invalid user )?<F-USER>.*?</F-USER> (?:from )?<HOST>%(__on_port_opt)s(?: ssh\d*)?%(__suff)s$
+ ^User <F-USER>\S+|.*?</F-USER> not allowed because account is locked%(__suff)s
+ ^<F-MLFFORGET>Disconnecting</F-MLFFORGET>(?: from)?(?: (?:invalid|authenticating)) user <F-USER>\S+</F-USER> <HOST>%(__on_port_opt)s:\s*Change of username or service not allowed:\s*.*\[preauth\]\s*$
+ ^Disconnecting: Too many authentication failures(?: for <F-USER>\S+|.*?</F-USER>)?%(__suff)s$
+ ^<F-NOFAIL>Received <F-MLFFORGET>disconnect</F-MLFFORGET></F-NOFAIL> from <HOST>%(__on_port_opt)s:\s*11:
+ <mdre-<mode>-other>
+ ^<F-MLFFORGET><F-MLFGAINED>Accepted \w+</F-MLFGAINED></F-MLFFORGET> for <F-USER>\S+</F-USER> from <HOST>(?:\s|$)
+
+cmnfailed-any = \S+
+cmnfailed-ignore = \b(?!publickey)\S+
+cmnfailed-invalid = <cmnfailed-ignore>
+cmnfailed-nofail = (?:<F-NOFAIL>publickey</F-NOFAIL>|\S+)
+cmnfailed = <cmnfailed-<publickey>>
+
+mdre-normal =
+# used to differentiate "connection closed" with and without `[preauth]` (fail/nofail cases in ddos mode)
+mdre-normal-other = ^<F-NOFAIL><F-MLFFORGET>(?:Connection (?:closed|reset)|Disconnect(?:ed|ing))</F-MLFFORGET></F-NOFAIL>%(__authng_user)s <ADDR>%(__on_port_opt)s(?:: (?!Too many authentication failures)[^\[]+)?(?: \[preauth\])?\s*$
+
+mdre-ddos = ^(?:Did not receive identification string from|Timeout before authentication for) <HOST>
+ ^kex_exchange_identification: (?:read: )?(?:[Cc]lient sent invalid protocol identifier|[Cc]onnection (?:closed by remote host|reset by peer))
+ ^Bad protocol version identification '(?:[^']|.*?)' (?:from )?<HOST>%(__suff)s$
+ ^<F-NOFAIL>SSH: Server;Ltype:</F-NOFAIL> (?:Authname|Version|Kex);Remote: <HOST>-\d+;[A-Z]\w+:
+ ^Read from socket failed: Connection <F-MLFFORGET>reset</F-MLFFORGET> by peer
+ ^(?:banner exchange|ssh_dispatch_run_fatal): Connection from <HOST><__on_port_opt>: (?:invalid format|(?:message authentication code incorrect|[Cc]onnection corrupted) \[preauth\])
+
+# same as mdre-normal-other, but as failure (without <F-NOFAIL> with [preauth] and with <F-NOFAIL> on no preauth phase as helper to identify address):
+mdre-ddos-other = ^<F-MLFFORGET>(?:Connection (?:closed|reset)|Disconnect(?:ed|ing))</F-MLFFORGET>%(__authng_user)s <ADDR>%(__on_port_opt)s(?:: (?!Too many authentication failures)[^\[]+)?\s+\[preauth\]\s*$
+ ^<F-NOFAIL><F-MLFFORGET>(?:Connection (?:closed|reset)|Disconnect(?:ed|ing))</F-MLFFORGET></F-NOFAIL>%(__authng_user)s <ADDR>(?:%(__on_port_opt)s(?:: (?!Too many authentication failures)[^\[]+)?|\s*)$
+
+mdre-extra = ^Received <F-MLFFORGET>disconnect</F-MLFFORGET> from <HOST>%(__on_port_opt)s:\s*14: No(?: supported)? authentication methods available
+ ^Unable to negotiate with <HOST>%(__on_port_opt)s: no matching <__alg_match> found.
+ ^Unable to negotiate a <__alg_match>
+ ^no matching <__alg_match> found:
+# part of mdre-ddos-other, but user name is supplied (invalid/authenticating) on [preauth] phase only:
+mdre-extra-other = ^<F-MLFFORGET>Disconnected</F-MLFFORGET>(?: from)?(?: (?:invalid|authenticating)) user <F-USER>\S+|.*?</F-USER> (?:from )?<HOST>%(__on_port_opt)s \[preauth\]\s*$
+
+mdre-aggressive = %(mdre-ddos)s
+ %(mdre-extra)s
+# mdre-extra-other is fully included within mdre-ddos-other:
+mdre-aggressive-other = %(mdre-ddos-other)s
+
+# Parameter "publickey": nofail (default), invalid, any, ignore
+publickey = nofail
+# consider failed publickey for invalid users only:
+cmnfailre-failed-pub-invalid = ^Failed publickey for invalid user <F-USER>(?P<cond_user>\S+)|(?:(?! from ).)*?</F-USER> from <HOST>%(__on_port_opt)s(?: ssh\d*)?(?(cond_user): |(?:(?:(?! from ).)*)$)
+# consider failed publickey for valid users too (don't need RE, see cmnfailed):
+cmnfailre-failed-pub-any =
+# same as invalid, but consider failed publickey for valid users too, just as no failure (helper to get IP and user-name only, see cmnfailed):
+cmnfailre-failed-pub-nofail = <cmnfailre-failed-pub-invalid>
+# don't consider failed publickey as failures (don't need RE, see cmnfailed):
+cmnfailre-failed-pub-ignore =
+
+cfooterre = ^<F-NOFAIL>Connection from</F-NOFAIL> <HOST>
+
+failregex = %(cmnfailre)s
+ <mdre-<mode>>
+ %(cfooterre)s
+
+# Parameter "mode": normal (default), ddos, extra or aggressive (combines all)
+# Usage example (for jail.local):
+# [sshd]
+# mode = extra
+# # or another jail (rewrite filter parameters of jail):
+# [sshd-aggressive]
+# filter = sshd[mode=aggressive]
+#
+mode = normal
+
+#filter = sshd[mode=aggressive]
+
+ignoreregex =
+
+maxlines = 1
+
+journalmatch = _SYSTEMD_UNIT=sshd.service + _COMM=sshd
+
+# DEV Notes:
+#
+# "Failed \S+ for .*? from <HOST>..." failregex uses non-greedy catch-all because
+# it is coming before use of <HOST> which is not hard-anchored at the end as well,
+# and later catch-all's could contain user-provided input, which need to be greedily
+# matched away first.
+#
+# Author: Cyril Jaquier, Yaroslav Halchenko, Petr Voralek, Daniel Black and Sergey Brester aka sebres
+# Rewritten using prefregex (and introduced "mode" parameter) by Serg G. Brester.