Linked Questions

34
votes
3answers
80k views

Debugging rules in Iptables [duplicate]

How can I know how many packets were dropped by my iptables rules ?? Is there any debugging mechanism to see which rule is Dropping my packet or Accepting it ??
20
votes
3answers
16k views

Debugging iptables and common firewall pitfalls?

This is a proposed Canonical Question about understanding and debugging the software firewall on Linux systems. In response to EEAA's answer and @Shog's comment that we need a suitable canonical Q&...
12
votes
4answers
17k views

How to Enable IPtables TRACE Target on Debian Squeeze (6)

I am trying to use the TRACE target of IPtables but I can't seem to get any trace information logged. I want to use what is described here: Debugger for Iptables. From the iptables man for TRACE: ...
5
votes
2answers
9k views

View requests that iptables has blocked

Is it possible to view or enable a log that shows what requests iptables is blocking? I am trying to track down a request that iptables is blocking, but shouldn't be (because of an exception rule that ...
1
vote
2answers
1k views

Why does these iptables rules does not work

I think a bit more detail is needed. I have opened a new cafe in my area and people are downloading stuff that are increasing my bills, so I want to block protocols on my router and then re enable it ...
0
votes
1answer
1k views

fail2ban not correctly modifying the iptables effectively?

I just installed fail2ban in NetinVM (a constellation of virtual machines inside a VM) so far so good, I install in a specific machine (10.5.1.13) where ssh is on 2222 (all on root) From other ...
-1
votes
2answers
2k views

Troubleshooting firewall and routing on Linux

Are there any tools or API hooks for troubleshooting iptables or routing on Linux? (besides the obvious -j LOG) In other words: what to do when tables with 200 or 300 firewalling rules after adding a ...
2
votes
1answer
721 views

nmap lists host as up despite being black listed

I have an iptables rule setup that marks addresses as suspicious if they connect on certain ports or any unopen ports. If more than three consecutive connections are made without authentication, then ...
0
votes
0answers
363 views

iptables: How to list a chain as well as its subchains

I want to understand why a kind of specific packets through or not through a chain (OUTPUT for example), but the chain was written in a structured manner which can jump to a lot of sub chains, within ...
1
vote
0answers
130 views

Regulate OpenVPN users' access to specific websites

More specifically, I push the route for 5 websites to the clients via the server config. However, I would like to block CLIENTS's access to one of these websites on an ad-hoc basis. In order to ...