• 20 Posts
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Joined 11 个月前
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Cake day: 2025年3月3日

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  • whitelist of allowed ips

    Not exactly.

    If source is whitelisted, Accept (avoid being locked out myself)

    So all IP’s are allowed to begin with, but some (“my” IP’s like at home, my office etc) are on a whitelist ahead of everything else. They can’t become blacklisted to avoid myself becoming locked out. Then it’s the drop all on the blacklisted, followed by portscan detection. Only after that the ‘normal’ rules (allow https, smtp etc) begin.



  • Well, here is the CPU load:

    And there is no increase on delay’s or jitter compared to what i’m already facing on the WAN itself.

    It keep’s 6000+ hosts with possible harmful intend away from the ports I need/want open to the world. Actually, the router -while still being bored- offloads the services behind it. I really can’t see a reason not to keep doing it. But, sure, it’s a personal choice.



  • I’m using RouterOS. In the firewall rules you can create a rule that if an IP touches a port, it get added to a address list (optional with a time-out). So my FW rules begin like this:

    1. If source is whitelisted, Accept (avoid being locked out myself)
    2. If source IP is in the blacklist, drop all
    3. if source IP tries to connect to port 21,22,25,137-139, 113 (and a bunch of others) add it to the blacklist

    So using a portscanner will touch ports I’m not running any service on (like telnet) and you’ll be blocked. A time-out of one week on the blacklist usually gives me an blacklist of 6500+ addresses.

    This too has endless possibilities. t.ex. like port knocking. (‘touch’ one or more ports in a specified sequence in a specified time to be allowed to access the actual service port)





  • It does not. It does not uses ports at all. Fail2ban monitors your logfiles and activates the firewall to block IP’s that matched your rules.

    t.ex. You can block an IP that tried to access https://<url>/admin. You can block an IP that used wrong credentials x times to login on an ssh port. Or block one that tried to relay via your mailserver. The duration is configurable and alternative duration can be configured for recidivists.

    And yes, you can whitelist IP’s to avoid locking yourself out. The possibilities are endless.