Update cheatsheets

tldr/linux/arptables

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+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# arptables
+
+> Manage ARP filtering rules using the `nftables` backend.
+> Part of the `xtables-nft` suite for ARP packet filtering.
+> More information: <https://manned.org/arptables>.
+
+- List all ARP rules in the filter table:
+
+`sudo arptables {{[-L|--list]}}`
+
+- Append a rule to drop ARP packets from a specific IP address:
+
+`sudo arptables {{[-A|--append]}} INPUT {{[-s|--source-ip]}} {{192.168.0.1}} {{[-j|--jump]}} DROP`
+
+- Delete a specific rule from the INPUT chain by its rule number:
+
+`sudo arptables {{[-D|--delete]}} INPUT {{rule_number}}`
+
+- Flush all rules in the filter table:
+
+`sudo arptables {{[-F|--flush]}}`
+
+- Set the default policy of the OUTPUT chain to ACCEPT:
+
+`sudo arptables {{[-P|--policy]}} OUTPUT ACCEPT`
+
+- Save the current ARP rules to a file:
+
+`sudo arptables-save > {{path/to/file}}`