如何应对 sshd 蛮力攻击

Question

我最近收到了来自 OSSEC HIDS 的通知，警告我关于 SSHD 暴力攻击。为了完整起见，我在下面报告整个消息：

OSSEC HIDS Notification.
2020 Mar 03 12:00:17

Received From: commodore->/var/log/auth.log
Rule: 5712 fired (level 10) -> "SSHD brute force trying to get access to the system."
Src IP: 188.166.xxx.xxx
Portion of the log(s):

Mar  3 12:00:16 commodore sshd[21661]: Disconnected from invalid user www 188.166.xxx.xxx port 45788 [preauth]
Mar  3 12:00:16 commodore sshd[21661]: Invalid user www from 188.166.xxx.xxx port 45788
Mar  3 11:59:53 commodore sshd[21204]: Disconnected from invalid user weblogic 188.166.xxx.xxx port 34582 [preauth]
Mar  3 11:59:53 commodore sshd[21204]: Invalid user weblogic from 188.166.xxx.xxx port 34582
Mar  3 11:59:08 commodore sshd[21198]: Disconnected from invalid user stack 188.166.xxx.xxx port 40352 [preauth]
Mar  3 11:59:08 commodore sshd[21198]: Invalid user stack from 188.166.xxx.xxx port 40352
Mar  3 11:58:28 commodore sshd[21193]: Disconnected from invalid user jira 188.166.xxx.xxx port 46186 [preauth]
Mar  3 11:58:28 commodore sshd[21193]: Invalid user jira from 188.166.xxx.xxx port 46186

为了加强对我机器的 SSH 访问，我将我的公钥上传到我的 VPS 并禁用了 SSH 密码身份验证。总结一下，我编辑/etc/ssh/sshd_config如下：

PermitRootLogin no
PubkeyAuthentication yes
PasswordAuthentication no
Banner none
AllowTcpForwarding no
GatewayPorts no
AddressFamily inet

目前我的iptables规则是：

-P INPUT ACCEPT
-P FORWARD DROP
-P OUTPUT ACCEPT
-N DOCKER
-N DOCKER-ISOLATION-STAGE-1
-N DOCKER-ISOLATION-STAGE-2
-N DOCKER-USER
-A INPUT -i lo -j ACCEPT
-A INPUT -s 127.0.0.0/8 ! -i lo -j REJECT --reject-with icmp-port-unreachable
-A INPUT -p icmp -m state --state NEW -m icmp --icmp-type 8 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -j ACCEPT
-A INPUT -p tcp -m tcp --dport 80 -m state --state NEW -j ACCEPT
-A INPUT -p tcp -m tcp --dport 443 -m state --state NEW -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables_INPUT_denied: " --log-level 7
-A INPUT -j REJECT --reject-with icmp-port-unreachable
-A FORWARD -j DOCKER-USER
-A FORWARD -j DOCKER-ISOLATION-STAGE-1
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT
-A FORWARD -m limit --limit 5/min -j LOG --log-prefix "iptables_FORWARD_denied: " --log-level 7
-A FORWARD -j REJECT --reject-with icmp-port-unreachable
-A DOCKER-ISOLATION-STAGE-1 -i docker0 ! -o docker0 -j DOCKER-ISOLATION-STAGE-2
-A DOCKER-ISOLATION-STAGE-1 -j RETURN
-A DOCKER-ISOLATION-STAGE-2 -o docker0 -j DROP
-A DOCKER-ISOLATION-STAGE-2 -j RETURN
-A DOCKER-USER -j RETURN

由于我不是经验丰富的管理员，如果您能建议我希望对此类攻击使用什么响应，我将不胜感激。我的 sshd 和防火墙配置是否足够或需要采取进一步措施，例如阻止 188.166.xxx.xxx ip 地址？

Answer 1

您可以使用fail2ban. 这将在尝试过多的情况下临时阻止 ip 地址。

您可以查看：如何在 Ubuntu Server 18.04 上安装 fail2ban。它也适用于其他版本。