aiuto...ci stanno provando?

[X3noN]

Ciao a tutti,

oggi guardando auth.log mi sono accorto che ci sono una miriade ti tentativi di login tramite ssh non andati a buon fine da utenti che non esistono...è qualcuno che ci sta provando?

Mi sto sinceramente preoccupando perchè la cosa è iniziata 5 giorni fa e sta continuando...

vi posto un pezzo del log...

AIUTO!!!

Nov  7 20:09:17 master sshd[14684]: Invalid user admin from ::ffff:81.176.184.20
Nov  7 20:09:17 master sshd[14684]: error: Could not get shadow information for NOUSER
Nov  7 20:09:17 master sshd[14684]: Failed password for invalid user admin from ::ffff:81.176.184.20 port 49515 ssh2
Nov  7 20:09:18 master sshd[14686]: Invalid user user from ::ffff:81.176.184.20
Nov  7 20:09:18 master sshd[14686]: error: Could not get shadow information for NOUSER
Nov  7 20:09:18 master sshd[14686]: Failed password for invalid user user from ::ffff:81.176.184.20 port 49554 ssh2
Nov  7 20:09:19 master sshd[14688]: Failed password for root from ::ffff:81.176.184.20 port 49600 ssh2
Nov  7 20:09:20 master sshd[14690]: Failed password for root from ::ffff:81.176.184.20 port 49634 ssh2
Nov  7 20:09:21 master sshd[14692]: Failed password for root from ::ffff:81.176.184.20 port 49677 ssh2
Nov  7 20:09:22 master sshd[14694]: Invalid user test from ::ffff:81.176.184.20
Nov  7 20:09:22 master sshd[14694]: error: Could not get shadow information for NOUSER
Nov  7 20:09:22 master sshd[14694]: Failed password for invalid user test from ::ffff:81.176.184.20 port 49717 ssh2
Nov  7 20:09:26 master sshd[14696]: Invalid user test from ::ffff:81.176.184.20
Nov  7 20:09:26 master sshd[14696]: error: Could not get shadow information for NOUSER
Nov  7 20:09:26 master sshd[14696]: Failed password for invalid user test from ::ffff:81.176.184.20 port 49773 ssh2
Nov  7 20:09:27 master sshd[14698]: Invalid user test from ::ffff:81.176.184.20
Nov  7 20:09:27 master sshd[14698]: error: Could not get shadow information for NOUSER
Nov  7 20:09:27 master sshd[14698]: Failed password for invalid user test from ::ffff:81.176.184.20 port 49926 ssh2
Nov  7 20:09:28 master sshd[14700]: Invalid user test from ::ffff:81.176.184.20
Nov  7 20:09:28 master sshd[14700]: error: Could not get shadow information for NOUSER
Nov  7 20:09:28 master sshd[14700]: Failed password for invalid user test from ::ffff:81.176.184.20 port 49978 ssh2
Nov  7 20:09:29 master sshd[14702]: Failed password for root from ::ffff:81.176.184.20 port 50018 ssh2
Nov  7 20:09:30 master sshd[14704]: Failed password for root from ::ffff:81.176.184.20 port 50070 ssh2
Nov  7 20:09:31 master sshd[14706]: Failed password for root from ::ffff:81.176.184.20 port 50105 ssh2
Nov  7 20:09:41 master sshd[14708]: Failed password for root from ::ffff:81.176.184.20 port 50139 ssh2
Nov  7 21:25:13 master sshd[14723]: Invalid user test from ::ffff:81.176.184.20
Nov  7 21:25:13 master sshd[14723]: error: Could not get shadow information for NOUSER
Nov  7 21:25:13 master sshd[14723]: Failed password for invalid user test from ::ffff:81.176.184.20 port 34701 ssh2
Nov  7 21:25:14 master sshd[14725]: Invalid user guest from ::ffff:81.176.184.20
Nov  7 21:25:14 master sshd[14725]: error: Could not get shadow information for NOUSER
Nov  7 21:25:14 master sshd[14725]: Failed password for invalid user guest from ::ffff:81.176.184.20 port 34744 ssh2
Nov  7 21:25:15 master sshd[14727]: Invalid user admin from ::ffff:81.176.184.20
Nov  7 21:25:15 master sshd[14727]: error: Could not get shadow information for NOUSER
Nov  7 21:25:15 master sshd[14727]: Failed password for invalid user admin from ::ffff:81.176.184.20 port 34797 ssh2
Nov  7 21:25:16 master sshd[14729]: Invalid user admin from ::ffff:81.176.184.20
Nov  7 21:25:16 master sshd[14729]: error: Could not get shadow information for NOUSER
Nov  7 21:25:16 master sshd[14729]: Failed password for invalid user admin from ::ffff:81.176.184.20 port 34840 ssh2
Nov  7 21:25:18 master sshd[14731]: Invalid user user from ::ffff:81.176.184.20
Nov  7 21:25:18 master sshd[14731]: error: Could not get shadow information for NOUSER
Nov  7 21:25:18 master sshd[14731]: Failed password for invalid user user from ::ffff:81.176.184.20 port 34888 ssh2
Nov  7 21:25:19 master sshd[14733]: Failed password for root from ::ffff:81.176.184.20 port 34951 ssh2
Nov  7 21:25:20 master sshd[14735]: Failed password for root from ::ffff:81.176.184.20 port 34987 ssh2
Nov  7 21:25:21 master sshd[14737]: Failed password for root from ::ffff:81.176.184.20 port 35019 ssh2
Nov  7 21:25:22 master sshd[14739]: Invalid user test from ::ffff:81.176.184.20
Nov  7 21:25:22 master sshd[14739]: error: Could not get shadow information for NOUSER
Nov  7 21:25:22 master sshd[14739]: Failed password for invalid user test from ::ffff:81.176.184.20 port

[HexDEF6]

Anch'io ne ho tonnellate di log del genere....
Spero tu abbia disabilitato l'accesso da root tramite ssh e le password degli utenti normali siano "sicure"!

Ciao!

[X3noN]

si per quello sono abbastanza tranquillo...da remoto root non si può collegare e gli users hanno una pass di almeno 8 char....nella norma direi...

speriamo bene!

[ilsensine]

Decisamente, ci hanno provato E anche con una certa insistenza, direi. Forse con qualche script.

[HexDEF6]

Originariamente inviato da ilsensine
Decisamente, ci hanno provato E anche con una certa insistenza, direi. Forse con qualche script.

io ho circa una decina di macchine connesse in rete con accesso ssh (di solito o firewall o server vari che devo amministrare da remoto) e su tutte mi sono trovato log del genere... direi che sono script...
di solito provano a loggarsi come: root, user, guest, admin ,test, nobody, patrick
inoltre se provi a spostare la porta di ssh i vari "attacchi" si fermano (quindi presumo che se non trovano la 22 aperta nemmeno ci provano)...
Mi sa che provo a farmi un bel port knocking cosi la 22 sembra sempre chiusa!

Ciao!

[HexDEF6]

Ho provato questo:
http://www.zeroflux.org/knock/

in questa maniera ad uno scan delle porte risulta che la 22 e' chiusa... ma basta bussare bene e la porta si apre (solo per l'ip che bussa!

Mi sa che lo installo ovunque..... a meno di controindicazioni (ho dovuto cambiare un attimo il firewall... ma niente di drastico) gravi...

Ciao!

[HexDEF6]

Ecco cosa usano per provare a trovare server ssh con password "deboli":

http://www.k-otik.com/exploits/08202004.brutessh2.c.php

Ciao!