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Burp Collaborator SMTP Interaction Failure

William | Last updated: Sep 30, 2022 08:28AM UTC

OS: Linux JAR: 2022.8.4 Hi! I've set up a Collaborator server following the Portswigger guidance, and now have a successfully deployed instance that allows us to catch call back nicely. No port changes were made, and the template provided on the setup page was used basically without any modification except required fields. However, when running the healthcheck with the Collaborator server in Burpsuite, our collaborator is consistently failing the 'Server SMTP Connection over port 25' poll, with the message 'The SMTP response of the capture server was not as expected, perhaps this is not a collaborator server.'. Not sure why this would be the case given we've deployed it as advised - I've confirmed it's not a network issue as the firewall rules are in place (AWS Security Group), and I'm able to directly poll the Collaborator's SMTP instance on port 25 from the same machine I'm running the Burpsuite Collaborator Healthcheck on. All other healthchecks return green. When running the below command, only DNS collaborator interactions are recorded, not SMTP. 'nc 1bdq3ub2n2gvhk0nzpaa1smfe6kw8l.collaborator.example.com 25 220 ***********************************************' Any advice is appreciated!

Michelle, PortSwigger Agent | Last updated: Oct 03, 2022 08:03AM UTC

Thanks for your message. Can you temporarily stop your Collaborator server and check to see if something else installed on the machine is using port 25? If another service isn't using that port, can you please email a copy of your Collaborator configuration file and the output you see as you start it up to support@portswigger.net, please?

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