Domain Name System Nfs Not Allowing Hosts Specif

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Asked 3 years ago

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I am having an issue where NFS is refusing to allow hosts that are specified in the config file to mount the share.

I am running an NFS server on Debian 10, BTRFS filesystem.

my /etc/exports reads:

/share  192.220.189.0/24(rw,sync,no_subtree_check) *.domain.lan(rw,sync,no_subtree_check)

I am trying to mount from host.domain.lan, but when I try to mount the share I get the following:

mount.nfs: access denied by server while mounting server.domain.lan:/share

The server log reads:

rpc.mountd[PID]: refused mount request from <host.domain.lan's ip> for /share (/share): unmatched host

I have verified that the server can resolve host.domain.lan’s hostname courtesy of a local DNS server.

The mounting DOES work if I explicitly specify host.domain.lan in /etc/exports as opposed to *.domain.lan. This will not do however as I want to serve the folder to an entire subdomain of FQDNs.

I can find nothing about this online, and I have exhausted every option I can think of, please help!

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asked Aug 14, 2021 at 7:52

](https://serverfault.com/users/798036/james)

james

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Is that your only export?

– Michael Hampton

Commented Aug 14, 2021 at 13:03
@MichaelHampton No, I have another export set up exactly like the one in the post.

– james

Commented Aug 14, 2021 at 16:02

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1 Answer

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Likely the domain name is not resolving correctly in DNS.

What do you get if you use the host command on the server to try to resolve the client’s ip address to a hostname? DNS may not have the correct reverse mapping set up for this to work.

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answered Aug 14, 2021 at 14:55

](https://serverfault.com/users/675696/user10489)

user10489

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It returns Host not found: 3(NXDOMAIN). Which is weird, because if I explicitly specify host.domain.lan, it mounts just fine.

– james

Commented Aug 14, 2021 at 16:05
It’s not weird… it’s not even unusual. The name is registered for forward resolution but not reverse resolution. It has to be registered for both directions for this to work.

– user10489

Commented Aug 14, 2021 at 19:05
Works perfectly after setting up reverse DNS resolution. Thank you! For anyone reading this in the future, when setting up your PTR records, remember to use host.domain.lan., not host.domain.lan. Would have saved me hours knowing this.

– james

Commented Aug 14, 2021 at 19:52