[SOLVED] The RPC server is unavailable

I'm trying to join a Windows 10 workstation to a Samba Active Directory. Using a "join" too: ForensiT's Traswiz, I attempted the join but it always fails with the message:

The following error occured attempting to connect to the domain hprs.locl: The RPC server is unavailable.

I assume this means an rpc server on the Linux box needs to be running. I started '/usr/sbin/rpcbind -l -w' and '/sbin/rpc.stad', but that didn't help. Another poster elsewhere said this is not the right rpc: "This is not Samba, nor even DCE/RPC, it is another unix-historical RPC system (ONCRPC) used essentially only for NFS".

Does anyone have an idea of what Linux rpc server Windows might be looking for?

I've never seen Windows (native) services use Linux's RPC (portmapper, rpcbind). Run rpcinfo to see your Linux RPC services. Windows (and Samba) does have RPC that is probably what this means (access via rpcclient with is part of Samba). If you have Samba running,

rpcclient  -U "" -N -I 192.168.20.1 -c srvinfo atr2
	ATR2           Wk Sv Tim PrQ Unx NT SNT [ATr2 RG 2023/12/15 09:33:17] atr2 SMB/CIFS 4.19
	platform_id     :	500
	os version      :	6.1
	server type     :	0x809a23

rpcclient  -U "" -N -I 192.168.20.23 -c srvinfo zorah
	ZORAH          Wk Sv NT SNT PtB LMB 
	platform_id     :	500
	os version      :	4.0
	server type     :	0x2059003

where .1 is Linux and .23 is Windows. I've never heard of "ONCRPC" and I've used NFS. I don't know much about modern Windows or AD but at least you know it's not rpcbind now. Probably something in the Samba config or Windows setup.

I figured out my problem. It was a DNS issue. Windows workstations on the "old" DC were able to figure out where the DC DNS was located -- possibly because I used a different DNS backend mechanism on that DC. I fixed the problem by updating the Windows IPv4 settings and explicitly specifying the DC as DNS.

Well, the DC being the DNS wasn't my only issue. After I got past that, subsequent attempts to join using Profwiz continued to fail with the "RPC Server is unavailable" error. I tried numerous things and finally gave up and decided to join to the domain the usual way vial Control Panel > System > Advanced System settings > Computer Name, but when I entered the credentials of the domain admin I got the error that the admin's password was expired! That was interesting because that password was set to never expire. I changed the password on the DC anyway and tried again and this time the join worked. After rebooting I then ran Profwiz on another domain user on that computer and this time it worked, no RPC error.

It seems that Profwiz's "RPC Server is unavailable" is a catch-all error resulting from some underlying problem or problems. In my case a) DNS not pointing to DC and b) "expired" domain admin password. There may be other conditions that would cause the RPC error, but at least I know to check for these two problems in the future.