NFS server unable to open connection to tcp6/udp6 networks

This document (7011354) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 11 Service Pack 2

Situation

When starting the nfs server daemon, the following output is received:

sles11sp2:~ # /etc/init.d/nfsserver start
Starting kernel based NFS server: idmapd mountdrpc.mountd: svc_tli_create:
could not open connection for udp6
rpc.mountd: svc_tli_create: could not open connection for tcp6
rpc.mountd: svc_tli_create: could not open connection for udp6
rpc.mountd: svc_tli_create: could not open connection for tcp6
rpc.mountd: svc_tli_create: could not open connection for udp6
rpc.mountd: svc_tli_create: could not open connection for tcp6
statd nfsdrpc.nfsd: address family inet6 not supported by protocol TCP
sm-notify
done
sles11sp2:~ #

Resolution

First, it is important to emphasize that the messages shown above are likely only informational. On a system without IPv6 enabled, it is normal to fail to find ipv6, tcp6, udp6, etc. While those messages may be an annoyance, they are usually cosmetic. There is no real need to disable them, nor be concerned by them, unless ipv6 *is* desired, in which case it should simply be turned on in YaST --> Network Devices --> Network Settings --> Global Options tab.

If IPv6 is intentionally disabled and it is preferred to disable these messages also, it can be done. HOWEVER, this must be used with CAUTION, because if this method is put in place and later the system is upgraded to SLES 12, the rpc layer (rpcbind, aka sunrpc) will fail to initialize, and this change would need to be reversed. (See also TID https://www.suse.com/support/kb/doc?id=7017144 ) Also note that on SLES 12, these the messages don't appear and no effort to suppress them is needed.

Here is the method for SLES 11: Edit /etc/netconfig (a file used by rpcbind) and disable the lines that configure udp6 and tcp6:

udp        tpi_clts      v     inet     udp     -       -
tcp        tpi_cots_ord v     inet     tcp     -       -
#udp6       tpi_clts      v     inet6    udp     -       -
#tcp6       tpi_cots_ord v     inet6    tcp     -       -
rawip      tpi_raw       -     inet      -      -       -
local      tpi_cots_ord -     loopback -      -       -
unix       tpi_cots_ord -     loopback -      -       -

Cause

IPv6 was disabled globally in YaST2 but RPC calls still try to establish connections to tcp6 or udp6 networks as configured in /etc/netconfig.

Disclaimer

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