Error on trying to run a simple RPC program

Question

I am trying to run a simple RPC program which I have created using rpcgen. Its a simple factorial program. This is my first RPC program. The make works fine.Executables are also created. But when trying to run the executables, I get this error:

$sudo ./fact_server 
Cannot register service: RPC: Unable to receive; errno = Connection refused
unable to register (FACTPROGRAM, FACTVERSION, udp).

I tried running the same program on another pc with the same OS (ubuntu). It runs perfect there.

Answer 1

First you check that portmapper is working or not, use rpcinfo to check it. If you get any error then install portmap

Answer 2

Check whether the service is running using rpcinfo. Here's what I get.

$ rpcinfo 
   program version netid     address                service    owner
    100000    4    tcp6      ::.0.111               portmapper superuser
    100000    3    tcp6      ::.0.111               portmapper superuser
    100000    4    udp6      ::.0.111               portmapper superuser
    100000    3    udp6      ::.0.111               portmapper superuser
    100000    4    tcp       0.0.0.0.0.111          portmapper superuser
    100000    3    tcp       0.0.0.0.0.111          portmapper superuser
    100000    2    tcp       0.0.0.0.0.111          portmapper superuser
    100000    4    udp       0.0.0.0.0.111          portmapper superuser
    100000    3    udp       0.0.0.0.0.111          portmapper superuser
    100000    2    udp       0.0.0.0.0.111          portmapper superuser
    100000    4    local     /run/rpcbind.sock      portmapper superuser
    100000    3    local     /run/rpcbind.sock      portmapper superuser
        24    5    udp       0.0.0.0.3.99           -          superuser
        24    5    tcp       0.0.0.0.3.100          -          superuser

If the service is not running, you have to start it with rpcbind. On Ubuntu I needed root privileges to run the service.

Answer 3

There is a bug/feature in recent Linux releases of rpcbind - it is now not active/running after system boot, but should somehow be "socket activated" according to systemctl configuration rpcbind.service file in /usr/lib/systemd/system/:

[Install] 
Also=rpcbind.socket

Check this thread on same bug/feature caused Ubuntu issues (https://bugs.launchpad.net/ubuntu/+source/rpcbind/+bug/1558196).

The short answer to yours (ours) issue with rpcbind is - in order to run the RPC server code, do this amendment to systemctrl configuration of your system:

sudo systemctl add-wants multi-user.target rpcbind

Now, the intended way to set rpcbind running is to somehow access /var/run/rpcbind.sock, I would owe much to some Unix/Linux guru that may enlighten me on what RPC server application code shall do in order to achieve this rpcbind "socket activation" effect.