I've run into an interesting problem with the spamd SMTP banner. I have a few OpenBSD 3.7 mail gateways running Postfix that are members (from a DNS perspective) of an internal DNS domain such as mail.company.org. They are MX destinations for mail for company.com, and postfix reports to external SMTP servers as mail.company.com (the servers are NAT translated).
The issue I have is that spamd uses gethostname to build the SMTP banner so the name shown in the banner is of course mail.company.org and not mail.company.com. Postfix of course reports as mail.company.com. I'm wondering if changes could be made to spamd to accommodate this perhaps by allowing more customisation of the spamd SMTP banner, or perhaps adding a simple command line switch where the hostname could be supplied (eg: spamd -H mail.company.com). For the moment, although my C knowledge isn't that great, I have compiled a custom version of spamd with hard coded hostnames and this works OK. My interest with this is that initial connections to spamd are thus exposing the servers internal name. Whilst this is not really a great security problem in this situation it is undesirable. Any thoughts? Cheers, Tim.
