• Share
  • Dark

Why is my server logging: "dhcpd: send_packet: Invalid argument"?

  • Updated on 29 Dec 2016
  • 1 minute to read
  • Contributors 

dhcpd: send_packet: Invalid argumentdhcpd: dhcp.c:3730: Failed to send 300 byte long packet over fallback interface.

This error message is seen due to two different problems:

1.The server has a resource problem - specifically that the ARP cache (sometimes known as 'Neighbour table') is full.

2.The wrong error code (EINVAL instead of ENOBUFS) is being returned by the Operating System Kernel in some circumstances.  This error message was seen from Linux kernel 3.16, but the correct error was logged by Linux kernel 3.2.

The correct message would have reported "No buffer space available" instead of "Invalid argument".

Another message that might also be seen in newer versions of Linux (3.2 and above) in kern.log is:

ipv4: Neighbour table overflow.

Increasing the ARP cache can be achieved by adjusting the gc_thresh2 and gc_thresh3 linux kernel settings.

© 2001-2018 Internet Systems Consortium For assistance with problems and questions for which you have not been able to find an answer in our Knowledge Base, we recommend searching our community mailing list archives and/or posting your question there (you will need to register there first for your posts to be accepted). The bind-users and the dhcp-users lists particularly have a long-standing and active membership. ISC relies on the financial support of the community to fund the development of its open source software products. If you would like to support future product evolution and maintenance as well having peace of mind knowing that our team of experts are poised to provide you with individual technical assistance whenever you call upon them, then please consider our Professional Subscription Support services - details can be found on our main website.

Problems with this site? Email us at marketing@isc.org