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stop ban of legitimate users with multiple public keys (e. g. git, etc), thereby 

differentiate between "invalid user" (going banned earlier) and valid users with public keys, for which the rejects of not valid public keys (failures) will be retarded up to "Too many authentication failures" resp. disconnect without success (accepted public key).
pull/2014/head
sebres 2018-01-10 19:07:20 +01:00
parent c36fbdf743
commit 2112145eb4
3 changed files with 30 additions and 4 deletions
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4
config/filter.d/sshd.conf
View File

@ -34,7 +34,8 @@ prefregex = ^<F-MLFID>%(__prefix_line)s</F-MLFID>%(__pref)s<F-CONTENT>.+</F-CONT
cmnfailre = ^[aA]uthentication (?:failure|error|failed) for <F-USER>.*</F-USER> from <HOST>( via \S+)?\s*%(__suff)s$
^User not known to the underlying authentication module for <F-USER>.*</F-USER> from <HOST>\s*%(__suff)s$
^Failed \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 ).)*)$)
^Failed \S+ for invalid user <F-USER>(?P<cond_user>\S+)|(?:(?! from ).)*?</F-USER> from <HOST>%(__on_port_opt)s(?: ssh\d*)?(?(cond_user): |(?:(?:(?! from ).)*)$)
^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 ).)*)$)
^<F-USER>ROOT</F-USER> LOGIN REFUSED.* FROM <HOST>\s*%(__suff)s$
^[iI](?:llegal|nvalid) user <F-USER>.*?</F-USER> from <HOST>%(__on_port_opt)s\s*$
^User <F-USER>.+</F-USER> from <HOST> not allowed because not listed in AllowUsers\s*%(__suff)s$
@ -50,6 +51,7 @@ cmnfailre = ^[aA]uthentication (?:failure|error|failed) for <F-USER>.*</F-USER>
^<F-MLFFORGET>Disconnecting</F-MLFFORGET>: Too many authentication failures(?: for <F-USER>.+?</F-USER>)?%(__suff)s
^<F-NOFAIL>Received <F-MLFFORGET>disconnect</F-MLFFORGET></F-NOFAIL> from <HOST>: 11:
^<F-NOFAIL>Connection <F-MLFFORGET>closed</F-MLFFORGET></F-NOFAIL> by <HOST>%(__suff)s$
^<F-MLFFORGET><F-NOFAIL>Accepted publickey</F-NOFAIL></F-MLFFORGET> for \S+ from <HOST>(?:\s|$)
mdre-normal =

3
fail2ban/tests/config/filter.d/zzz-sshd-obsolete-multiline.conf
View File

@ -31,7 +31,8 @@ __alg_match = (?:(?:\w+ (?!found\b)){0,2}\w+)
cmnfailre = ^%(__prefix_line_sl)s[aA]uthentication (?:failure|error|failed) for .* from <HOST>( via \S+)?\s*%(__suff)s$
^%(__prefix_line_sl)sUser not known to the underlying authentication module for .* from <HOST>\s*%(__suff)s$
^%(__prefix_line_sl)sFailed \S+ for (?P<cond_inv>invalid user )?(?P<user>(?P<cond_user>\S+)|(?(cond_inv)(?:(?! from ).)*?|[^:]+)) from <HOST>%(__on_port_opt)s(?: ssh\d*)?(?(cond_user): |(?:(?:(?! from ).)*)$)
^%(__prefix_line_sl)sFailed \S+ for invalid user <F-USER>(?P<cond_user>\S+)|(?:(?! from ).)*?</F-USER> from <HOST>%(__on_port_opt)s(?: ssh\d*)?(?(cond_user): |(?:(?:(?! from ).)*)$)
^%(__prefix_line_sl)sFailed \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 ).)*)$)
^%(__prefix_line_sl)sROOT LOGIN REFUSED.* FROM <HOST>\s*%(__suff)s$
^%(__prefix_line_sl)s[iI](?:llegal|nvalid) user .*? from <HOST>%(__on_port_opt)s\s*$
^%(__prefix_line_sl)sUser .+ from <HOST> not allowed because not listed in AllowUsers\s*%(__suff)s$

27
fail2ban/tests/files/logs/sshd
View File

@ -141,10 +141,33 @@ Nov 11 08:04:52 redbamboo sshd[2737]: Failed password for invalid user test from
# failJSON: { "time": "2004-11-11T08:04:52", "match": true , "host": "127.0.0.1", "desc": "More complex injecting on auth-info ssh test@localhost, auth-info: ' from 10.10.1.2 port 55555 ssh2'" }
Nov 11 08:04:52 redbamboo sshd[2737]: Failed password for invalid user test from 127.0.0.1 port 58946 ssh2: from 10.10.1.2 port 55555 ssh2
# Failure on connect of invalid user with public keys:
# failJSON: { "time": "2005-07-05T18:22:44", "match": true , "host": "127.0.0.1", "desc": "Failed publickey for ..." }
Jul 05 18:22:44 mercury sshd[4669]: Failed publickey for graysky from 127.0.0.1 port 37954 ssh2: RSA SHA256:v3dpapGleDaUKf$4V1vKyR9ZyUgjaJAmoCTcb2PLljI
Jul 05 18:22:44 mercury sshd[4669]: Failed publickey for invalid user graysky from 127.0.0.1 port 37954 ssh2: RSA SHA256:v3dpapGleDaUKf$4V1vKyR9ZyUgjaJAmoCTcb2PLljI
# failJSON: { "time": "2005-07-05T18:22:45", "match": true , "host": "aaaa:bbbb:cccc:1234::1:1", "desc": "Failed publickey for ..." }
Jul 05 18:22:45 mercury sshd[4670]: Failed publickey for graysky from aaaa:bbbb:cccc:1234::1:1 port 37955 ssh2: RSA SHA256:v3dpapGleDaUKf$4V1vKyR9ZyUgjaJAmoCTcb2PLljI
Jul 05 18:22:45 mercury sshd[4670]: Failed publickey for invalid user graysky from aaaa:bbbb:cccc:1234::1:1 port 37955 ssh2: RSA SHA256:v3dpapGleDaUKf$4V1vKyR9ZyUgjaJAmoCTcb2PLljI
# Ignore tries of legitimate users with multiple public keys (gh-1263):
# failJSON: { "match": false }
Nov 28 09:16:03 srv sshd[32307]: Failed publickey for git from 192.0.2.1 port 57904 ssh2: ECDSA 0e:ff:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
# failJSON: { "match": false }
Nov 28 09:16:03 srv sshd[32307]: Failed publickey for git from 192.0.2.1 port 57904 ssh2: RSA 04:bc:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
# failJSON: { "match": false }
Nov 28 09:16:03 srv sshd[32307]: Postponed publickey for git from 192.0.2.1 port 57904 ssh2 [preauth]
# failJSON: { "match": false }
Nov 28 09:16:03 srv sshd[32307]: Accepted publickey for git from 192.0.2.1 port 57904 ssh2: DSA 36:48:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
# failJSON: { "match": false, "desc": "Should be forgotten by success/accepted public key" }
Nov 28 09:16:03 srv sshd[32307]: Connection closed by 192.0.2.1 [preauth]
# Failure on connect with valid user-name but wrong public keys (retarded to disconnect/too many errors, because of gh-1263):
# failJSON: { "match": false }
Nov 28 09:16:05 srv sshd[32310]: Failed publickey for git from 192.0.2.111 port 57910 ssh2: ECDSA 1e:fe:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
# failJSON: { "match": false }
Nov 28 09:16:05 srv sshd[32310]: Failed publickey for git from 192.0.2.111 port 57910 ssh2: RSA 14:ba:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
# failJSON: { "match": false }
Nov 28 09:16:05 srv sshd[32310]: Disconnecting: Too many authentication failures for git [preauth]
# failJSON: { "time": "2004-11-28T09:16:05", "match": true , "host": "192.0.2.111", "desc": "Should catch failure - no success/no accepted public key" }
Nov 28 09:16:05 srv sshd[32310]: Connection closed by 192.0.2.111 [preauth]
# failJSON: { "match": false }
Nov 23 21:50:19 sshd[8148]: Disconnecting: Too many authentication failures for root [preauth]