Hi,

It might be the difference between a missing entry in a zone file, and a missing zone file. Maybe it is the lookup mechanism that fails, rather than it checking the IP address itself. It might be another rule set that is trying to do a reverse lookup (eg hostname), and it barfs out at that point.

Maybe increase the logging verbosity and check the logs again?

Cheers,

Marco

On 10/10/2022 22:54, Ken Smith via GLLUG wrote:

I'm trying to sort out a Rocky 8.5 server that has sendmail installed. (Please don't go on a diversion about how I should tell the owner to dump sendmail and switch to exim or postfix - save that for another thread please. )

I'm pretty good with sendmail but this problem has me a bit foxed. I'd value some suggestions of where to look as I think I'm not seeing the wood for the trees.

It will send from addresses in the local network, without auth, because I have "connect:192.168.123   relay" in the access file - that being the local LAN.

I've tested sasl auth and that is authenticating.

Using telnet from an IP off their LAN (over a VPN) I can connect using TLS (openssl s_client etc etc) and authenticate (perl -MMIME::Base64 etc etc)  it accepts my credentials and then if I try to send a message I get "Relaying denied. IP name lookup failed [my local ip]" The same happens with a test using Thunderbird.

If I do the same test from the host that sendmail is on, it works fine.

Also if I do the same test from another host on the same LAN it works fine.

Somehow its complaining about the source IP in authenticated sessions outside the LAN range.

In the test from my local LAN (172.16.0.x), over a VPN, the remote dns can't resolve the reverse dns of my LAN. I've done a similar test with another sendmail site and remote auth is working fine.

Maybe sendmail is doing reverse DNS when it shouldn't be.

Suggestions most welcome....

Thanks

Ken






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