Red Hat Enterprise Linux Server release 6.5 (Santiago)

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We see snmpd[2055]: Wrong netlink message type 3 errors in message file..How can we fix it?

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Netlink transfers information between kernel and user space processes. Does the server have a working network connection?

We've seen this before, however the customer was using a third-party snmpd so we didn't investigate further.

This is printed by snmpd in agent/mibgroup/ip-mib/data_access/arp_netlink.c function fillup_entry_info() but I don't know the SNMP code so I'm not precisely sure why it gets printed.

The RT netlink messages start at 16 (see include/uapi/linux/rtnetlink.h in the kernel source) so there's no message type of 3. It's possible the snmpd is just catching a NLMSG_DONE indicating the end of a Netlink message (see include/uapi/linux/netlink.h in the kernel source) and this is just harmless noise.

The print of the line in snmpd looks like it's in a debug wrapper, so turning snmp debugging off or raising the default log level could be an option:

static int 
fillup_entry_info(netsnmp_arp_entry *entry, struct nlmsghdr *nlmp)
{
    struct ndmsg   *rtmp;
    struct rtattr  *tb[NDA_MAX + 1], *rta;
    int             length;

    rtmp = (struct ndmsg *) NLMSG_DATA(nlmp);
    switch (nlmp->nlmsg_type) {
    case RTM_NEWNEIGH:
        if (rtmp->ndm_state == NUD_FAILED)
            entry->flags = NETSNMP_ACCESS_ARP_ENTRY_FLAG_DELETE;
        else
            entry->flags = 0;
        break;
    case RTM_DELNEIGH:
        entry->flags = NETSNMP_ACCESS_ARP_ENTRY_FLAG_DELETE;
        break;
    case RTM_GETNEIGH:
        return 0;
    default:
        DEBUGMSGTL(("access:netlink:arp",
                    "Wrong Netlink message type %d\n", nlmp->nlmsg_type));
        return -1; 
    }   

If you're using the snmpd supplied and supported by Red Hat, feel free to raise a support case and mention this Discussions thread in the case description.

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