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sshd: additionally aggressive filter rules - no matching cipher resp. no matching key exchange method (gh-1545, gh-1117)

pull/1209/head
sebres 2016-11-14 12:59:37 +01:00 committed by sebres
parent 628789f9a9
commit 3276bd6d54
2 changed files with 21 additions and 6 deletions
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15
config/filter.d/sshd.conf
View File

@ -22,6 +22,7 @@ _daemon = sshd
__pref = (?:(?:error|fatal): (?:PAM: )?)?
# optional suffix (logged from several ssh versions) like " [preauth]"
__suff = (?: \[preauth\])?\s*
__on_port_opt = (?: port \d+)?(?: on \S+(?: port \d+)?)?
# single line prefix:
__prefix_line_sl = %(__prefix_line)s%(__pref)s
@ -33,24 +34,26 @@ mode = %(normal)s
normal = ^%(__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>(?: port \d+)?(?: ssh\d*)?(?(cond_user): |(?:(?:(?! from ).)*)$)
^%(__prefix_line_sl)sFailed \S+ for (?P<cond_inv>invalid user )?(?P<user>(?P<cond_user>\S+)|(?(cond_inv)(?:(?! from ).)*?|[^:]+)) from <HOST>%(__on_port_opt)s(?: ssh\d*)?(?(cond_user): |(?:(?:(?! from ).)*)$)
^%(__prefix_line_sl)sROOT LOGIN REFUSED.* FROM <HOST>\s*%(__suff)s$
^%(__prefix_line_sl)s[iI](?:llegal|nvalid) user .*? from <HOST>(?: port \d+)?\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$
^%(__prefix_line_sl)sUser .+ from <HOST> not allowed because listed in DenyUsers\s*%(__suff)s$
^%(__prefix_line_sl)sUser .+ from <HOST> not allowed because not in any group\s*%(__suff)s$
^%(__prefix_line_sl)srefused connect from \S+ \(<HOST>\)\s*%(__suff)s$
^%(__prefix_line_sl)sReceived disconnect from <HOST>: 3: .*: Auth fail%(__suff)s$
^%(__prefix_line_sl)sReceived disconnect from <HOST>%(__on_port_opt)s: 3: .*: Auth fail%(__suff)s$
^%(__prefix_line_sl)sUser .+ from <HOST> not allowed because a group is listed in DenyGroups\s*%(__suff)s$
^%(__prefix_line_sl)sUser .+ from <HOST> not allowed because none of user's groups are listed in AllowGroups\s*%(__suff)s$
^%(__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=<HOST>\s.*%(__suff)s$
^%(__prefix_line_sl)s(error: )?maximum authentication attempts exceeded for .* from <HOST>(?: port \d*)?(?: ssh\d*)? \[preauth\]$
^%(__prefix_line_sl)s(error: )?maximum authentication attempts exceeded for .* from <HOST>%(__on_port_opt)s(?: ssh\d*)? \[preauth\]$
^%(__prefix_line_ml1)sUser .+ not allowed because account is locked%(__prefix_line_ml2)sReceived disconnect from <HOST>: 11: .+%(__suff)s$
^%(__prefix_line_ml1)sDisconnecting: Too many authentication failures for .+?%(__prefix_line_ml2)sConnection closed by <HOST>%(__suff)s$
^%(__prefix_line_ml1)sConnection from <HOST> port \d+(?: on \S+ port \d+)?%(__prefix_line_ml2)sDisconnecting: Too many authentication failures for .+%(__suff)s$
^%(__prefix_line_ml1)sConnection from <HOST>%(__on_port_opt)s%(__prefix_line_ml2)sDisconnecting: Too many authentication failures for .+%(__suff)s$
ddos = ^%(__prefix_line_sl)sDid not receive identification string from <HOST>%(__suff)s$
^%(__prefix_line_sl)sReceived disconnect from <HOST>: 14: No supported authentication methods available%(__suff)s$
^%(__prefix_line_sl)sReceived disconnect from <HOST>%(__on_port_opt)s: 14: No supported authentication methods available%(__suff)s$
^%(__prefix_line_sl)sUnable to negotiate with <HOST>%(__on_port_opt)s: no matching (?:cipher|key exchange method) found.
^%(__prefix_line_ml1)sConnection from <HOST>%(__on_port_opt)s%(__prefix_line_ml2)sUnable to negotiate a (?:cipher|key exchange method)%(__suff)s$
^%(__prefix_line_ml1)sSSH: Server;Ltype: (?:Authname|Version|Kex);Remote: <HOST>-\d+;[A-Z]\w+:.*%(__prefix_line_ml2)sRead from socket failed: Connection reset by peer%(__suff)s$
aggressive = %(normal)s

12
fail2ban/tests/files/logs/sshd-ddos
View File

@ -25,3 +25,15 @@ Nov 24 23:46:43 host sshd[32686]: fatal: Read from socket failed: Connection res
Nov 25 01:34:12 srv sshd[123]: Received disconnect from 127.0.0.1: 14: No supported authentication methods available [preauth]
# failJSON: { "time": "2004-11-25T01:35:13", "match": true , "host": "127.0.0.1", "desc": "No supported authentication methods" }
Nov 25 01:35:13 srv sshd[123]: error: Received disconnect from 127.0.0.1: 14: No supported authentication methods available [preauth]
# gh-1545:
# failJSON: { "time": "2004-11-26T13:03:29", "match": true , "host": "192.0.2.1", "desc": "No matching cipher" }
Nov 26 13:03:29 srv sshd[45]: Unable to negotiate with 192.0.2.1 port 55419: no matching cipher found. Their offer: aes256-cbc,rijndael-cbc@lysator.liu.se,aes192-cbc,aes128-cbc,arcfour128,arcfour,3des-cbc,none [preauth]
# gh-1117:
# failJSON: { "time": "2004-11-26T13:03:30", "match": true , "host": "192.0.2.2", "desc": "No matching key exchange method" }
Nov 26 13:03:30 srv sshd[45]: fatal: Unable to negotiate with 192.0.2.2 port 55419: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1
# failJSON: { "match": false }
Nov 26 15:03:30 host sshd[22440]: Connection from 192.0.2.3 port 39678 on 192.168.1.9 port 22
# failJSON: { "time": "2004-11-26T15:03:31", "match": true , "host": "192.0.2.3", "desc": "Multiline - no matching key exchange method" }
Nov 26 15:03:31 host sshd[22440]: fatal: Unable to negotiate a key exchange method [preauth]