ntop / ntop/nProbe

[cento] Bridge mode: banned hosts are not blocked

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Description

Our nProbe Cento version is:
banned_allowed.zip

sudo cento-bridge --version
v.1.18.230113
Built OS:      Ubuntu 18.04.6 LTS
System Id:     L12030D0200000792--U12030D0288924EBB--OL
GIT rev:       1.18-stable:fd21960eff2b6e8a982905afff5d4cc93adba35b:20230113
License:       A6ooFU9tOYlxJucJ1kWEXMyplTIwW9TPhqGphubx+hqEtv7Y/fuuIK8eydrpS/Di
               0oP8CIEfMElXlKLpSOueLzjX5+o9NQ4lbexJU17o+e9PSFRNyL8l/rTHMQSF22Rc
               AZied00KOTvzAr7GlR16HxoKKdKtRWn1QfYWUQPAamZvH7LnmQgavMz9SqJE7pnO
               za4ATg3H0eAGv0Joww4xCJfTIk0DmTdeMWm6fuO6qLEnYhgabgVTVHC8fmeWzzV3
               MRrS8pVShgAH1ojhDCekUEIQ9OoLDt0nnOmzyTn554n4cBTBPchVxbBphLGAommY
               RHSVEA5iMNmj0gGf6JolUA==
License Hash:  80F15EBC2E2F46036A77877E04B05FCE1674571903FBB1CF23 [valid license]
License Type:  Time-limited License
Lic. Duration: Until Tue Jan 24 15:51:43 2023 [6 days left]

Right now we have the following issue with nProbe Cento:
cento is standing as a bridge between two different physical interfaces (eth0 and eth1). It forwards client's traffic to the internet with filtering capabilities.
In order to filter blocklisted website (website id is defined as HTTP Host or TLS SNI) we've configured the following:

# cat bridge.conf
[bridge]
default = forward
banned-hosts = discard

# cat banned.example
[example.org](http://example.org/)
[google.com](http://google.com/)
[www.google.com](http://www.google.com/)

# cento execution:
sudo cento-bridge -i eth0,eth1 --bridge-conf bridge.conf --banned-hosts banned.example --dpi-level 2

However we're out of success: specified banned hosts are not blocked what we can check this out by executing the cmd on the client side (that's a separate virtual machine):

curl -L [example.org](http://example.org/)  
curl -L [google.com](http://google.com/) 
curl -L [www.google.com](http://www.google.com/)

We expect that HTTP(S) requests to the hosts specified in banned.example should be discarded (dropped) but this does not happened.

The pcap file is attached.

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the supplied bridge.conf, banned.example, execution command, and pcap, using the reported Ubuntu 18.04.6 environment as the reproduction context. Check why HTTP Host and TLS SNI matches for the listed hosts are not discarded in bridge mode; done means requests to those hosts are blocked while other traffic is forwarded.

Written by the indexing model from the issue text.

Assessment

Tech stack
linux
Domain
networking
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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