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72 lines
1.9 KiB
Markdown
72 lines
1.9 KiB
Markdown
# iblock
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iblock is an inetd program adding the client IP to a Packet Filter table.
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It is meant to be used to block scanner connecting on unused ports.
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Upon connection, the IP is added to a PF table and all established connections with this IP are killed. You need to use a PF bloking rule using the table.
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# How to use
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## Add a dedicated user
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```
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useradd -s /sbin/nologin _iblock
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```
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## Configure doas
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Add in `/etc/doas.conf`:
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```
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permit nopass _iblock cmd /sbin/pfctl
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```
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## Configure inetd
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Start inetd service with this in `/etc/inetd.conf`:
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```
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666 stream tcp nowait _iblock /usr/local/sbin/iblock iblock
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666 stream tcp6 nowait _iblock /usr/local/sbin/iblock iblock
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```
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You can change the PF table by adding it as a parameter like this:
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In this example, the parameter `blocklist` will add IPs to the `blocklist` PF table.
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```
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666 stream tcp nowait _iblock /usr/local/sbin/iblock iblock blocklist
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666 stream tcp6 nowait _iblock /usr/local/sbin/iblock iblock blocklist
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```
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Default is "iblocked" table.
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## Configure packet filter
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Use this in `/etc/pf.conf`, choose which ports will trigger the ban from the variable:
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```
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# services triggering a block
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blocking_tcp="{ 21 23 53 111 135 137:139 445 1433 25565 5432 3389 3306 27019 }"
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table <blocked> persist
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block in quick from <blocked> label iblock
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pass in quick on egress inet proto tcp to port $blocking_tcp rdr-to 127.0.0.1 port 666
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pass in quick on egress inet6 proto tcp to port $blocking_tcp rdr-to ::1 port 666
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```
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Don't forget to reload the rules with `pfctl -f /etc/pf.conf`.
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# Get some statistics
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Done! You can see IP banned using `pfctl -t blocked -T show` and iBlock will send blocked addresses to syslog.
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In the example I added a label to the block rule, you can use `pfctl -s labels` to view statistics from this rule, [see documentation for column meaning](https://man.openbsd.org/pfctl#s~8).
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# TODO
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- A proper man page
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