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Known dnsmasq warnings

Warnings commonly seen in dnsmasq's log file (/var/log/pihole.log) and the Pi-hole diagnosis system.

ignoring zone transfer request from ADDRESS

Zone transfer requests (AXFR) are refused unless auth-sec-servers or auth-peers is set. The address requesting the AXFR is logged.

DHCP request for unsupported hardware type (X) received on Y

dnsmasq only supports Ethernet on *BSD. The integer X describes the hardware type (see /usr/include/linux/if_arp.h for definitions). Y is the name of the receiving interface.

Unknown protocol version from route socket

As the warning says. No action is performed in this case.

No IPv4 address found for HOSTNAME

Lookup for an A record in the cache returned no result.

HOSTNAME is a CNAME, not giving it to the DHCP lease of ADDRESS

A hostname claimed by a DHCP client is a known CNAME. dnsmasq does not allow the DHCP clients to take this name.

not giving name HOSTNAME to the DHCP lease of ADDRESS because the name exists in SOURCE with address CACHE_ADDR

If HOSTNAME is known through a HOSTS file or config (see SOURCE) and the DHCP address ADDRESS does not match the address in the cache (CACHE_ADDR), dnsmasq prevents giving the name to a DHCP client. This prevents possible hostname hijacking by malicious devices.

unknown interface IF_NAME in bridge-interface

If the interface on which the DHCPv6 request was received is an alias of some other interface (as specified by the bridge-interface option), dnsmasq needs to look for DHCPv6 contexts associated with the aliased interface instead of with the aliasing one. This warning complains that the referenced interface does not exist.

DHCP packet received on IF_NAME which has no address

No DHCP context has been configured for this interface. Check your DHCP settings.

Error sending DHCP packet to ADDRESS: MSG

This can fail when, e.g., iptables DROPS destination 255.255.255.255. Check your firewall settings.

DHCP range ADDRESS_FROM -- ADDRESS_TO is not consistent with netmask SUBNET_MASK

This warning highlights that one of the two addresses is outside of the configured subnet mask. As a consequence, not all addresses may be reachable from configured hosts leading to unexpected behavior on the clients. Make your DHCP settings consistent.

Ignoring duplicate dhcp-option OPTNUM

DHCP options specified more than once are ignored. The corresponding option ID is given by OPTNUM

HOSTNAME has more than one address in hostsfile, using ADDRESS for DHCP

Some people like to keep all static IP addresses in /etc/hosts. dnsmasq goes through /etc/hosts and sets static addresses for any DHCP config records which don't have an address and whose name matches where dnsmasq maintains the invariant that any IP address can appear in at least one DHCP host.

duplicate IP address ADDRESS (HOSTNAME) in dhcp-config directive

As the warning says.

cache size greater than 10000 may cause performance issues, and is unlikely to be useful.

This causes the cache to consume a lot on memory and slows down cache lookups. As expiring cache entries naturally make room for new records, a large cache does not give any advantages beyond a certain level. This level is typically not very high. Try reducing the cache. Watch out for cache-evictions. If they are zero over a long time, your cache is larger than what you need.

warning: failed to change owner of PIDFILE: MSG

Changing the ownership of the PID file (PIDFILE) to the user dnsmasq will be running as failed. A descriptive error message (MSG) is given to explain why the chown failed.

setting --bind-interfaces option because of OS limitations

Only affects non-Linux builds. bind-dynamic is not supported on non-Linux. dnsmasq falls back to bind-interfaces

warning: interface NAME does not currently exist

As the warning says. Likely caused by an interface=NAME option where the interface NAME does not exist. Check if your operating system may have changed from simple (like eth0) to predictable (like enp2s0) interface names. Update your configuration accordingly.

warning: ignoring resolv-file flag because no-resolv is set

This points to a conflicting configuration that may not behave as expected. Remove either the resolv-file or the --no-resolv option.

warning: no upstream servers configured

Only local names can be answered as no server=... lines are defined.

warning: PATH inaccessible

The TFTP prefix (set by tftp-prefix) is inaccessible or not a directory.

warning: TFTP directory PATH inaccessible

One of the defined TFTP prefix (comma-separated arguments of tftp-prefix) is inaccessible or not a directory.

restricting maximum simultaneous TFTP transfers to NUMBER

If a limited range of ports is in use, this also limits the number of concurrent TFTP transfers.

script process killed by signal SIGNUM

A script helper was killed by an external signal (SIGNUM).

script process exited with status EXITCODE

A script helper exited with a non-success return code (EXITCODE).

failed to access RESOLV_FILE: MSG

This line is logged when dnsmasq fails to access one of the files defined through resolv-file. This warning is printed only once per file.

no servers found in RESOLV_FILE, will retry

The read file was empty. dnsmasq will read it again. This warning is printed only once per file.

Insecure DS reply received for DOMAIN, check domain configuration and upstream DNS server DNSSEC support

A query was marked BOGUS because a DS query could not be validated (returned INSECURE).

discarding DNS reply: subnet option mismatch

When the EDNS0 option add-subnet is in use, dnsmasq needs to check the reply. If the returned subnet does not match, the reply is treated as invalid.

nameserver ADDRESS refused to do a recursive query

Upstream at address ADDRESS is missing the RA (recursion available) bit. This warning is printed only once per server.

possible DNS-rebind attack detected: NAME

A and AAAA answers are checked against possible rebind attacks when stop-dns-rebind is enabled. See rebind-domain-ok=/domain/ for adding exceptions.

reducing DNS packet size for nameserver ADDRESS to SAFE_PKTSZ

When receiving answers from upstream only with a smaller maximum DNS packet size, dnsmasq warns about this and remembers this decision per server for some time (defaulting to 60 seconds).

If you see this message continuously, you are affected by some unusual truncation on the path from your Pi-hole to the configured upstream server. You can get rid of the warning by adding a config file like /etc/dnsmasq.d/99-edns.conf and adding

edns-packet-max=1232

After running pihole restartdns your Pi-hole will not even try larger packet sizes (the default is 4096). Check out our unbound guide for a comment about the particular value of 1232.

Ignoring query from non-local network

dnsmasq can be configured to only accept queries from at-most-one-hop-away addresses using the option local-service. Other queries are discarded in this case.

This is ment to be a safe default to keep otherwise unconfigured installations safe. Note that local-service is ignored if any access-control config is in place (interface, except-interface, listen-address or auth-server).

Maximum number of concurrent DNS queries reached (max: NUMBER)

The configured maximum number of concurrent DNS queries for a given server is reached. The system is either very busy at the moment or not receiving queries from the configured upstream. Check your connectivity or the upstream DNS server status.

The warning can also be printed when being spammed with an excessive amount of duplicates or when the upstream server never replies for specific domains. Check your logs and try to identify similarities between the query directly preceding this warning and earlier queries in /var/log/pihole.log. Try to find out if your upstream does maybe never reply to specific domains and fix this.

This warning is printed at most once every five seconds (per upstream server) to help mitigate unlimited log file growth.

Maximum number of concurrent DNS queries to DOMAIN reached (max: NUMBER)

Same as above but for a specific domain.

ignoring invalid line in lease database: STRING STRING STRING STRING ...

An invalid line in the lease file has been skipped.

ignoring invalid line in lease database, bad address: ADDRESS

Address found in the lease file is neither a valid IPv4 nor a valid IPv6 address. The line is skipped.

Ignoring domain CONFIG_DOMAIN for DHCP host name HOSTNAME

A DHCP client is not allowed to claim name HOSTNAME in the current DHCP configuration.

overflow: NUMBER log entries lost

When using asynchroneous logging and the disk is too slow, we can loose log lines during busy times. This can be avoided by decreasing the system load or switching to synchroneous logging. Note that synchroneous logging has the disadvantage of blocking DNS resolution when waiting for the log to be written to disk.

failed to create listening socket for ADDRESS: MSG

A failure to bind addresses given by listen-address is accepted when dnsmasq is configured with bind-dynamic.

failed to create listening socket for port NUMBER: MSG

Same as above but for a port rather than an address.

LOUD WARNING: listening on ADDRESSS may accept requests via interfaces other than IFNAME

When using bind-interfaces, the only access control is the addresses dnsmasq is listening on. There's nothing to avoid a query to the address of an internal interface arriving via an external interface where we don't want to accept queries, except that in the usual case the addresses of internal interfaces are RFC1918. When bind-interfaces in use, and we listen on an address that looks like it's probably globally routeable, this warning is printed.

LOUD WARNING: use --bind-dynamic rather than --bind-interfaces to avoid DNS amplification attacks via these interface(s)

Advise printed when above's warning is printed. This warning is printed only once.

warning: using interface IF_NAME instead

When configuring an interface alias (like eth0:0), dnsmasq will be listening on the physical (e.g. eth0) interface, instead.

warning: no addresses found for interface IF_NAME

dnsmasq has been configured to listen on an interface that has no address assigned to it.

ignoring nameserver ADDRESS - local interface

At least one server directive is redundant and point to the dnsmasq instance itself. The server is ignored.

ignoring nameserver ADDRESS - cannot make/bind socket: MSG

dnsmasq failed to allocate a socket for the mentioned server. The server is ignored.

no address range available for DHCP request with subnet selector SUBNET

No DHCP context has been configured for this subnet selector. Check your DHCP settings.

no address range available for DHCP request via ADDRESS

No DHCP context has been configured for this address. Check your DHCP settings.

no address range available for DHCP request via IF_NAME

No DHCP context has been configured for this interface. Check your DHCP settings.

This warning is expected during debug log generation as Pi-hole is trying to request a DHCP lease on all available interfaces. We do this to test that the server replies properly.

When an interface does not have a DHCP configuration (such as the loopback interface lo, or other special interfaces such as docker0), this warning is printed. You can safely ignore it when it happens only during DHCP testing, e.g., during Pi-hole debug log generation. If it happens often, you can use the option no-dhcp-interface=IF_NAME (insert the interface name here) to specifically disable DHCP on this interface.

disabling DHCP static address ADDRESS for HOSTNAME

Static DHCP leases are disabled when sending a DHCPDECLINE packet.

not using configured address ADDRESS because it is leased to MAC

Not handing out configured address because it is already actively used to another device with hardware address MAC.

not using configured address ADDRESS because it is in use by the server or relay

Handing out addresses used by known critical infrastructure (like the DHCP server or a relay) is prevented to avoid IP address duplication issues.

This can happen when you have configured a static address assignment for the IP address of your Pi-hole. As this could result in an IP address conflict, Pi-hole offers a different free address from your configured DHCP pool. As this means Pi-hole behaves differently than you configured it to, it issues a warning.

The solution would be to either remove the static reservation for the Pi-hole itself (see ADDRESS in the warning) or simply accept this warning as it should only happen during debug log generation. When this warning appears outside of a running DHCP test, check that your Pi-hole is indeed using a static address.

not using configured address ADDRESS because it was previously declined

As the warning says. Check your log file for reasons of a prior refusal to hand out this lease. This warning is at most logged once every 10 minutes for a given address.

cannot send DHCP/BOOTP option NUMBER: no space left in packet

Use less DHCP options as the space for options is limited and cannot be extended (RFC2131).

cannot send RFC3925 option: too many options for enterprise number NUMBER

A maximum packet length of 250 bytes has to be ensured for dhcp-option = vi-encap:13,17,... configurations.

no address range available for DHCPv6 request from relay at ADDRESS

No DHCPv6 context has been configured for this address. Check your DHCPv6 settings.

no address range available for DHCPv6 request via IF_NAME

No DHCPv6 context has been configured for this interface. Check your DHCPv6 settings.

If you do not have an upstreams IPv6 connection (use, e.g., test-ipv6.com for testing), Pi-hole does not have any address prefix it could use to build DHCPv6 addresses causing this warning on every DHCPv6 request. The solution will be to disable DHCPv6 in your Pi-hole.

disabling DHCP static address ADDRESS for TIME

Static DHCPv6 leases are disabled when sending a DHCP(6)DECLINE packet.

IPset: error: MSG

A non-critical error was encountered when trying to access an IPset device. A human-readable message explains it further.

warning: DIOCRADDADDRS: MSG

A non-critical error was encountered when trying to add an address to an existing ipset. A human-readable message explains it further.

warning: DIOCRDELADDRS: MSG

A non-critical error was encountered when trying to remove an address from an existing ipset. A human-readable message explains it further.


Last update: December 28, 2021
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