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Old 01-20-2016, 12:50 AM   #1
cathartes
LQ Newbie
 
Registered: Oct 2015
Location: U.S.A.
Distribution: Slackware, Tails
Posts: 20

Rep: Reputation: Disabled
dhcpcd repeated "expired option" IPv6-related output to syslog


My machine is running Slackware64 -current (as of 19 Jan 2016), and connects to my router via ethernet, using dhcpcd 6.8.2 managed by NetworkManager 1.0.10. My connection to the router is fine, however I'm vexed by output that is filling my syslog that I do not understand:

Code:
Jan 19 23:21:50 cathartes dhcpcd[687]: eth0: fe80::280:fff:fe11:7000: expired option 256
Jan 19 23:22:21 cathartes dhcpcd[687]: eth0: fe80::280:fff:fe11:7000: expired option 256
Jan 19 23:23:19 cathartes dhcpcd[687]: eth0: fe80::280:fff:fe11:7000: expired option 256
Jan 19 23:24:12 cathartes dhcpcd[687]: eth0: fe80::280:fff:fe11:7000: expired option 256
Jan 19 23:25:49 cathartes last message repeated 2 times
Jan 19 23:26:52 cathartes last message repeated 2 times
Jan 19 23:27:29 cathartes dhcpcd[687]: eth0: fe80::280:fff:fe11:7000: expired option 256
Jan 19 23:28:45 cathartes last message repeated 2 times
Jan 19 23:29:53 cathartes last message repeated 2 times
Jan 19 23:30:40 cathartes dhcpcd[687]: eth0: fe80::280:fff:fe11:7000: expired option 256
Jan 19 23:31:53 cathartes last message repeated 2 times
Jan 19 23:32:32 cathartes dhcpcd[687]: eth0: fe80::280:fff:fe11:7000: expired option 256
Jan 19 23:33:54 cathartes last message repeated 2 times
Jan 19 23:34:34 cathartes dhcpcd[687]: eth0: fe80::280:fff:fe11:7000: expired option 256
Jan 19 23:36:01 cathartes last message repeated 2 times

Since NM does not seem to support IPv6 with dhcpcd, I've disabled IPv6 for my connection using the nm-connections-editor. However, dhcpcd continues to post this output without end.

This is my (mostly) stock /etc/dhcpcd.conf:
Code:
# Allow users of this group to interact with dhcpcd via the control socket.
#controlgroup wheel

# Inform the DHCP server of our hostname for DDNS.
hostname

# Use the hardware address of the interface for the Client ID.
clientid
# or
# Use the same DUID + IAID as set in DHCPv6 for DHCPv4 ClientID as per RFC4361.
# Some non-RFC compliant DHCP servers do not reply with this set.
# In this case, comment out duid and enable clientid above.
#duid

# Persist interface configuration when dhcpcd exits.
persistent

# Rapid commit support.
# Safe to enable by default because it requires the equivalent option set
# on the server to actually work.
option rapid_commit

# A list of options to request from the DHCP server.
option domain_name_servers, domain_name, domain_search, host_name
option classless_static_routes
# Most distributions have NTP support.
option ntp_servers
# Respect the network MTU.
# Some interface drivers reset when changing the MTU so disabled by default.
#option interface_mtu

# A ServerID is required by RFC2131.
require dhcp_server_identifier

# Generate Stable Private IPv6 Addresses instead of hardware based ones
slaac private

# A hook script is provided to lookup the hostname if not set by the DHCP
# server, but it should not be run by default.
nohook lookup-hostname

# We run wpa_supplicant from rc.inet1 and/or NM handles it on its own
nohook wpa_supplicant
A cursory search of the forums and DDG did not suggest an answer other than switching to dhclient (which supports IPv6). But I'm hoping there was another reason that I overlooked in ignorance as to why this output is produced.

Suggestions? Pointers? I'll take anything. Thank you!

Last edited by cathartes; 01-20-2016 at 07:48 PM. Reason: post still not sufficiently descriptive.
 
Old 01-20-2016, 07:46 PM   #2
cathartes
LQ Newbie
 
Registered: Oct 2015
Location: U.S.A.
Distribution: Slackware, Tails
Posts: 20

Original Poster
Rep: Reputation: Disabled
So the issue is not connected with NetworkManager or even dhcpcd at all. The IPv6 address shown (above) in my syslog is my router, and if I'm understanding things correctly, the syslog output is normal with the expiration (& renewal) of my machine's DHCP lease. The problem is that my DHCP leases shouldn't be so short!

But the configuration for my router (a Novatel T1114) claimed that the longevity of leases was already set to 1440 minutes by default. So what's up? Turns out the value showed in the router's web configuration UI, for whatever reason, wasn't the actual value set "under the hood". Setting another large lease value and then saving the change correctly sets the longevity of the lease, and the output literally filling up my syslog goes away.

So the *real* problem was my complete ignorance of IPv6 compounded by a small bug in my router's configuration UI. Sorry, everyone!
 
  


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