SSHパスワードへの攻撃(ブルートフォースアタック)が頻発しているようです。
Guess what? SSH again!
While I'm aware that ISC readers probably don't have to be told, let's nevertheless try again to get the word out: If you are running any SSH server open to the Internet, and your usernames and passwords aren't at least 8 characters or so, your box is either owned by now, or about to be. It doesn't matter one bit what sort of device it is - those who run these scans have proven to be equally apt at taking over a Cisco router as they are at
subverting an iMac.
- Filter (by IP) who can get to your SSH. Firewalls rule! Who can't get to your SSH can't brute-force your SSH.
- Reconfigure your SSH to only use password protected SSH keys and not permit plain passwords anymore
- Use hard to guess usernames. Yes, usernames.
- Move your SSH off port 22 to some obscure corner of the port space
- Scan your own network to find out where you have SSH running before others do. You might be surprised ...
- Use "fail2ban", though this doesn't help a lot anymore against the distributed scans we see lately
- Educate your users to use good passwords. Yes, even those users who have proven to be immune to enlightment.
- Watch your logs. It's a great way to learn. And knowing what the "daily noise" looks like is imperative to spot "oddities"
Update: http://wiki.centos.org/HowTos/Network/SecuringSSH contains a decent list of tips on how to secure sshd.
Firewallの段階でIP制限を掛けるのが最強ですね(笑)
そのあと、TCP Wrapperを掛け~の、Password強度を上げ~の、システムログを見ぃ~のという対策を講じます。
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はい・・どこですか? rootのログインを平文Passwordで許可してるのは?(苦笑)