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train_wreck

Member

Registered: 2011-10-22

Posts: 97

dhcpcd keeps deleting & re-adding IPv6 default route every 5-10 second

I have Arch on an Intel NUC that is connected via WiFi to a Cisco RV340W router. The router has dual-stack IPv4 and IPv6 from Comcast, using IPv6 prefix delegation on the WAN interface, and IPv6 router advertisements providing internal LAN clients with IPv6 addresses. Every other device on this network is working fine, both IPv4 and v6. The NUC is using wpa_supplicant to automatically connect to the WiFi network on boot.

On the Arch NUC, it appears that dhcpcd keeps trying to intervene and make modifications to the IPv6 default route. I see the following in the systemd logs:

Jun 03 04:12:10 STREAMCLIENT dhcpcd[409]: wlp58s0: fe80::eebd:1dff:fe45:1ba2: no longer a default router
Jun 03 04:12:10 STREAMCLIENT dhcpcd[409]: wlp58s0: deleting default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:10 STREAMCLIENT dhcpcd[409]: wlp58s0: adding default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:15 STREAMCLIENT dhcpcd[409]: wlp58s0: fe80::eebd:1dff:fe45:1ba2: no longer a default router
Jun 03 04:12:15 STREAMCLIENT dhcpcd[409]: wlp58s0: deleting default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:15 STREAMCLIENT dhcpcd[409]: wlp58s0: adding default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:20 STREAMCLIENT dhcpcd[409]: wlp58s0: fe80::eebd:1dff:fe45:1ba2: no longer a default router
Jun 03 04:12:20 STREAMCLIENT dhcpcd[409]: wlp58s0: deleting default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:21 STREAMCLIENT dhcpcd[409]: wlp58s0: adding default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:26 STREAMCLIENT dhcpcd[409]: wlp58s0: fe80::eebd:1dff:fe45:1ba2: no longer a default router
Jun 03 04:12:26 STREAMCLIENT dhcpcd[409]: wlp58s0: deleting default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:26 STREAMCLIENT dhcpcd[409]: wlp58s0: adding default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:31 STREAMCLIENT dhcpcd[409]: wlp58s0: fe80::eebd:1dff:fe45:1ba2: no longer a default router
Jun 03 04:12:31 STREAMCLIENT dhcpcd[409]: wlp58s0: deleting default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:32 STREAMCLIENT dhcpcd[409]: wlp58s0: adding default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:37 STREAMCLIENT dhcpcd[409]: wlp58s0: fe80::eebd:1dff:fe45:1ba2: no longer a default router
Jun 03 04:12:37 STREAMCLIENT dhcpcd[409]: wlp58s0: deleting default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:37 STREAMCLIENT dhcpcd[409]: wlp58s0: adding default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:42 STREAMCLIENT dhcpcd[409]: wlp58s0: fe80::eebd:1dff:fe45:1ba2: no longer a default router
Jun 03 04:12:42 STREAMCLIENT dhcpcd[409]: wlp58s0: deleting default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:43 STREAMCLIENT dhcpcd[409]: wlp58s0: adding default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:48 STREAMCLIENT dhcpcd[409]: wlp58s0: fe80::eebd:1dff:fe45:1ba2: no longer a default router
Jun 03 04:12:48 STREAMCLIENT dhcpcd[409]: wlp58s0: deleting default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:48 STREAMCLIENT dhcpcd[409]: wlp58s0: adding default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:53 STREAMCLIENT dhcpcd[409]: wlp58s0: fe80::eebd:1dff:fe45:1ba2: no longer a default router
Jun 03 04:12:53 STREAMCLIENT dhcpcd[409]: wlp58s0: deleting default route via fe80::eebd:1dff:fe45:1ba2
Jun 03 04:12:53 STREAMCLIENT dhcpcd[409]: wlp58s0: adding default route via fe80::eebd:1dff:fe45:1ba2

Every time this happens, I lose IPv6 connectivity for a second, breaking v6 traffic entirely.

Here is the output of /etc/wpa_supplicant/wpa_supplicant.conf:

ctrl_interface=/run/wpa_supplicant
ctrl_interface_group=wheel
update_config=1
ap_scan=1
country=US
network={
        ssid="TestRV340W"
        psk="password"
}

Here is the output of /etc/dhcpcd.conf. I tried adding "nodhcp6" to disable DHCPv6, but this did nothing:

# A sample configuration for dhcpcd.
# See dhcpcd.conf(5) for details.

# 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
# Respect the network MTU. This is applied to DHCP routes.
option interface_mtu

# Most distributions have NTP support.
#option ntp_servers

# A ServerID is required by RFC2131.
require dhcp_server_identifier

# Generate SLAAC address using the Hardware Address of the interface
#slaac hwaddr
# OR generate Stable Private IPv6 Addresses based from the DUID
slaac private
noipv4ll

So how do I stop dhcpcd from doing this? I would ideally like to disable DHCPv6 entirely, and have dhcpcd use only IPv4, since the router is sending IPv6 RA messages to configure hosts. DHCPv6 is not necessary.

seth

Member

Registered: 2012-09-03

Posts: 61,182

Re: dhcpcd keeps deleting & re-adding IPv6 default route every 5-10 second

Tried any of

noipv6rs
noipv6
ipv4only

?

Don't forget to restart dhcpcd.

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rsmarples

Member

Registered: 2009-05-12

Posts: 287

Re: dhcpcd keeps deleting & re-adding IPv6 default route every 5-10 second

I'm pretty sure wpa_supplicant has nothing to do with this error and it's probably not a dhcpcd configuration error either.
The telling line is this:

wlp58s0: fe80::eebd:1dff:fe45:1ba2: no longer a default router

In dhcpcd, that diagnostic is logged if the router used to be a default router but has now announced it no longer is by setting it's lifetime to zero.
https://roy.marples.name/cgit/dhcpcd.gi … nd.c#n1065

Verify this by capturing a tcpdump or wireshark trace

Zod

Member

From: Hoosiertucky

Registered: 2019-03-10

Posts: 634

Re: dhcpcd keeps deleting & re-adding IPv6 default route every 5-10 second

Disable IPv6...

https://wiki.archlinux.org/index.php/IPv6#Disable_IPv6