Questions tagged [iptables]
iptables allow creation of rules to define packet filtering behavior. The most reliable way to provide an iptables ruleset in a question is with the output of (as root): iptables-save -c
2,703 questions
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Docker iptables behavior
I have two Redhat 8 virtual machines. I'm running Docker on both, in this case as a host for the application called Graphite. The VMs started out identical to each other, and I pulled the same Docker ...
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1 answer
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iptables changes not having any effect [closed]
I was attempting to interrupt a TCP connection on my system, and was altering iptables rules using the iptables command. Nothing I did seemed to have any effect, though. Inserting and deleting rules ...
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2 votes
1 answer
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How to enable internet access for a bridge inside a Linux network namespace?
I've created two Linux network namespaces (ns1 and ns2), and inside each, I have: A bridge (ns1-br0, ns2-br0) A TAP device (tap0, tap1) connected to the respective bridge Each TAP device gets an IP ...
1 vote
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How packet can get lost between filter INPUT and security INPUT chains of iptables?
From this flowchart https://stuffphilwrites.com/wp-content/uploads/2024/05/FW-IDS-iptables-Flowchart-v2024-05-22.png I know that packet goes from the INPUT chain of the filter table right into the ...
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1 answer
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Iptables does not apply drop policy for other ports
I'm running a server where iptables is configured with a default DROP policy and I’ve only explicitly allowed certain ports (e.g., HTTP, HTTPS, SSH on port 22, etc.). Despite never adding a rule for ...
1 vote
0 answers
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What does the phrase "consider native interface" refer to when the nftables wiki says that xt_bpf match is unsupported
In this list of unsupported xtables features. xt_bpf is listed as one of the unsupported features. The comment says to "consider native interface". But what interface is being referred to ...
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1 vote
2 answers
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IPIP tunnel between two docker containers on separate servers
Thank you in advance for your attention to my question and your help. I have a rather specific task. I need to set up an IPIP tunnel between two Docker containers located on different physical servers....
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1 answer
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How to set `iptables` so NTP works while internet access is blocked
I want to configure iptables such that it blocks everything except Date time synchronization over the internet using NTP and Access from machines in the LAN. I wrote the following script: # Reset ...
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