From 5561423be3b2d4636f5484183c3ad470fd326d06 Mon Sep 17 00:00:00 2001 From: sebres Date: Wed, 15 Mar 2017 18:00:53 +0100 Subject: [PATCH] filter.d/sshd.conf: fixed failregex format - some parts are optional, new ddos more precise rule (Connection reset by with host entry); closes gh-1719 --- config/filter.d/sshd.conf | 7 ++++--- .../tests/config/filter.d/zzz-sshd-obsolete-multiline.conf | 5 +++-- fail2ban/tests/files/logs/sshd | 7 ++++++- 3 files changed, 13 insertions(+), 6 deletions(-) diff --git a/config/filter.d/sshd.conf b/config/filter.d/sshd.conf index 8163aa03..320ab59c 100644 --- a/config/filter.d/sshd.conf +++ b/config/filter.d/sshd.conf @@ -41,17 +41,18 @@ cmnfailre = ^[aA]uthentication (?:failure|error|failed) for .* ^User .+ from not allowed because a group is listed in DenyGroups\s*%(__suff)s$ ^User .+ from not allowed because none of user's groups are listed in AllowGroups\s*%(__suff)s$ ^pam_unix\(sshd:auth\):\s+authentication failure;\s*logname=\S*\s*uid=\d*\s*euid=\d*\s*tty=\S*\s*ruser=\S*\s*rhost=\s.*%(__suff)s$ - ^(error: )?maximum authentication attempts exceeded for .* from %(__on_port_opt)s(?: ssh\d*)? \[preauth\]$ + ^(error: )?maximum authentication attempts exceeded for .* from %(__on_port_opt)s(?: ssh\d*)?%(__suff)s$ ^User .+ not allowed because account is locked%(__suff)s - ^Disconnecting: Too many authentication failures for .+?%(__suff)s + ^Disconnecting: Too many authentication failures(?: for .+?)?%(__suff)s ^Received disconnect from : 11: ^Connection closed by %(__suff)s$ mdre-normal = mdre-ddos = ^Did not receive identification string from %(__suff)s$ + ^Connection reset by %(__on_port_opt)s%(__suff)s ^SSH: Server;Ltype: (?:Authname|Version|Kex);Remote: -\d+;[A-Z]\w+: - ^Read from socket failed: Connection reset by peer \[preauth\] + ^Read from socket failed: Connection reset by peer%(__suff)s mdre-extra = ^Received disconnect from %(__on_port_opt)s:\s*14: No supported authentication methods available%(__suff)s$ ^Unable to negotiate with %(__on_port_opt)s: no matching (?:cipher|key exchange method) found. diff --git a/fail2ban/tests/config/filter.d/zzz-sshd-obsolete-multiline.conf b/fail2ban/tests/config/filter.d/zzz-sshd-obsolete-multiline.conf index 4f28e60f..d6eecd4b 100644 --- a/fail2ban/tests/config/filter.d/zzz-sshd-obsolete-multiline.conf +++ b/fail2ban/tests/config/filter.d/zzz-sshd-obsolete-multiline.conf @@ -40,12 +40,13 @@ cmnfailre = ^%(__prefix_line_sl)s[aA]uthentication (?:failure|error|failed) for ^%(__prefix_line_sl)spam_unix\(sshd:auth\):\s+authentication failure;\s*logname=\S*\s*uid=\d*\s*euid=\d*\s*tty=\S*\s*ruser=\S*\s*rhost=\s.*%(__suff)s$ ^%(__prefix_line_sl)s(error: )?maximum authentication attempts exceeded for .* from %(__on_port_opt)s(?: ssh\d*)? \[preauth\]$ ^%(__prefix_line_ml1)sUser .+ not allowed because account is locked%(__prefix_line_ml2)sReceived disconnect from : 11: .+%(__suff)s$ - ^%(__prefix_line_ml1)sDisconnecting: Too many authentication failures for .+?%(__prefix_line_ml2)sConnection closed by %(__suff)s$ - ^%(__prefix_line_ml1)sConnection from %(__on_port_opt)s%(__prefix_line_ml2)sDisconnecting: Too many authentication failures for .+%(__suff)s$ + ^%(__prefix_line_ml1)sDisconnecting: Too many authentication failures(?: for .+?)?%(__suff)s%(__prefix_line_ml2)sConnection closed by %(__suff)s$ + ^%(__prefix_line_ml1)sConnection from %(__on_port_opt)s%(__prefix_line_ml2)sDisconnecting: Too many authentication failures(?: for .+?)?%(__suff)s$ mdre-normal = mdre-ddos = ^%(__prefix_line_sl)sDid not receive identification string from %(__suff)s$ + ^%(__prefix_line_sl)sConnection reset by %(__on_port_opt)s%(__suff)s ^%(__prefix_line_ml1)sSSH: Server;Ltype: (?:Authname|Version|Kex);Remote: -\d+;[A-Z]\w+:.*%(__prefix_line_ml2)sRead from socket failed: Connection reset by peer%(__suff)s$ mdre-extra = ^%(__prefix_line_sl)sReceived disconnect from %(__on_port_opt)s:\s*14: No supported authentication methods available%(__suff)s$ diff --git a/fail2ban/tests/files/logs/sshd b/fail2ban/tests/files/logs/sshd index b53b3d96..fe19591c 100644 --- a/fail2ban/tests/files/logs/sshd +++ b/fail2ban/tests/files/logs/sshd @@ -168,7 +168,7 @@ Feb 12 04:09:21 localhost sshd[26713]: Disconnecting: Too many authentication fa # failJSON: { "match": false } Feb 12 04:09:18 localhost sshd[26713]: Connection from 115.249.163.77 port 51353 on 127.0.0.1 port 22 # failJSON: { "time": "2005-02-12T04:09:21", "match": true , "host": "115.249.163.77", "desc": "Multiline match with interface address" } -Feb 12 04:09:21 localhost sshd[26713]: Disconnecting: Too many authentication failures for root [preauth] +Feb 12 04:09:21 localhost sshd[26713]: Disconnecting: Too many authentication failures [preauth] # failJSON: { "time": "2004-11-23T21:50:37", "match": true , "host": "61.0.0.1", "desc": "New logline format as openssh 6.8 to replace prev multiline version" } Nov 23 21:50:37 myhost sshd[21810]: error: maximum authentication attempts exceeded for root from 61.0.0.1 port 49940 ssh2 [preauth] @@ -208,6 +208,11 @@ Nov 24 23:46:41 host sshd[32686]: SSH: Server;Ltype: Authname;Remote: 127.0.0.1- # failJSON: { "time": "2004-11-24T23:46:43", "match": true , "host": "127.0.0.1", "desc": "Multiline for connection reset by peer (3)" } Nov 24 23:46:43 host sshd[32686]: fatal: Read from socket failed: Connection reset by peer [preauth] +# gh-1719: +# failJSON: { "time": "2005-03-15T09:20:57", "match": true , "host": "192.0.2.39", "desc": "Singleline for connection reset by" } +Mar 15 09:20:57 host sshd[28972]: Connection reset by 192.0.2.39 port 14282 [preauth] + + # filterOptions: {"mode": "extra"} # several other cases from gh-864: