NFS and dynamic IP

[sabersong]

I have two linux machines networked using NFS through a Dynex wireless router. There is no way in the router to assign static IPs to the two computers, and I have three other devices also using the wireless router. Sometimes, the power goes out, sometimes my wife turns off one or both of the linux machines, sometimes we have to reset the router. In all these cases, IP addresses are subject to change. Is there any way to automatically mount an NFS share with a dynamic IP address?

[netztier]

Is there any way to automatically mount an NFS share with a dynamic IP address?

Try mDNS resolution as provided by avahi. Machines in a common broadcast domain can refer to each other by "hostname.local" [1]. I've found this to work out-of-the-box with Ubuntu Desktop installations. Ubuntu Server might need the additional installation of the package avahi-daemon.

Avahi is a Zeroconf implementation - Apple Inc. call theirs "Bonjour".


For example, two of my machines are called blaze and cube:

marc@cube:~$ ping blaze.local
PING blaze.local (172.20.125.30) 56(84) bytes of data.
64 bytes from blaze.mydomain.com (172.20.125.30): icmp_seq=1 ttl=64 time=0.131 ms
64 bytes from blaze.mydomain.com (172.20.125.30): icmp_seq=2 ttl=64 time=0.128 ms
^C
--- blaze.local ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.128/0.129/0.131/0.011 ms

and in the other direction:

marc@blaze:~$ ping cube.local
PING cube.local (172.20.125.31) 56(84) bytes of data.
64 bytes from cube.mydomain.com (172.20.125.31): icmp_seq=1 ttl=64 time=0.075 ms
64 bytes from cube.mydomain.com (172.20.125.31): icmp_seq=2 ttl=64 time=0.143 ms
...
^C
--- cube.local ping statistics ---
11 packets transmitted, 11 received, 0% packet loss, time 9999ms
rtt min/avg/max/mdev = 0.075/0.120/0.166/0.025 ms

Try using <hostname>.local in your /etc/fstab - it might just work.

regards

Marc


[1] note: if the DNS servers your systems are using (as per the content of /etc/resolv.conf) are considering themselves authoritative for the .local toplevel domain, avahi will detect this on startup and disable itself. You might want to involve the maintainer of your DNS in some discussions - I had to do the same with mine.

[sabersong]

Thank you! That was exactly what I needed.