# Troubleshooting Idrops in netstat



## drhowarddrfine (Aug 2, 2016)

I have a VPS server running FreeBSD 10.3-RELEASE-p4 and nginx so this might belong in the "Web Services" category. It contains three very low volume web sites that have  been up for about three years, all listening on the same nginx server. I was tinkering  with TLS and SSL ciphers on one of the clients by eliminating TLSv1 and TLSv1.1 with  different ciphers when I noticed my daily "Network interface status" report one  morning saying I was getting Idrops of 48665.


```
Network interface status:
    Name    Mtu Network       Address              Ipkts Ierrs Idrop    Opkts  Oerrs  Coll  Drop
    em0    1500 <Link#1>      xx:xx:3c:cd:7e:c7 225569570     0 48665    923463     0     0     0
    em0       - xxxx::xxx:3cf fe80::216:3cff:fe        0     -     -    4     -     -     -
    em0       - 107.xxx.xx.xx mysite1.co    94833     -     -        0    -     -     -
    em0       - 107.xxx.xx.0  mysite2.co   479981     -     -   920067    -     -     -
    lo0   16384 <Link#2>                             783     0     0    783     0     0     0
    lo0       - ::1           ::1                      0     -     -    0     -     -     -
    lo0       - xxxx::1%lo0   xxxx::1%lo0              0     -     -    0     -     -     -
    lo0       - your-net      localhost              783     -     -    783     -     -     -
```

I reverted my TLS/SSL changes but, the next day, that exact same number of Idrops happened and continued for a couple of days afterwards. I just don't know what I could have done to cause this and am looking for troubleshooting help since it's been so long since I've had to deal with this and forgotten nearly everything. All the sites seem to function normally and I should note that, besides the nginx server, there are also two nodejs servers listening via proxy. I do nothing with IPv6.

Here is part of `vmstat -z` where I notice FAILs:


```
ITEM                   SIZE  LIMIT     USED     FREE      REQ FAIL SLEEP

    UMA Hash:               128,      0,       5,      26,       7,   0,   0
    4 Bucket:                16,      0,       8,     496,   21344,   0,   0
    6 Bucket:                24,      0,       0,     336,     121,   0,   0
    8 Bucket:                32,      0,       2,     376,    1600,   0,   0
    12 Bucket:               48,      0,       0,       0,   97831,   0,   0
    16 Bucket:               64,      0,      12,     303,    9585,   8,   0
    32 Bucket:              128,      0,      14,     389,   46423,   0,   0
    64 Bucket:              256,      0,      20,     235,   48362,   0,   0
    128 Bucket:             512,      0,      19,     101,   23133,   0,   0

    mbuf_packet:            256,  30975,     256,     253,455561904,97330,   0
    mbuf:                   256,  30975,       2,     254, 2124523,   0,   0
    mbuf_cluster:          2048,   4840,     509,       3,   17874,194660,   2
    mbuf_jumbo_page:       4096,   2419,       0,       2,   10659,   0,   0
    mbuf_jumbo_9k:         9216,    716,       0,       0,       0,   0,   0
    mbuf_jumbo_16k:       16384,    403,       0,       0,       0,   0,   0
    mbuf_ext_refcnt:          4,      0,       0,       0,       0,   0,   0

    256 Bucket:            1024,      0,      27,      45,   56839,5856,   0
    vmem btag:               28,      0,    6648,    1848,   68924,  58,   0
```

I ran `netstat -s` and can post that here if it's OK for something that big or if someone wants something specific from that.

In addition, what can I do to see these drops without having to wait till the next day for the report? I know I can do `netstat -i` but that contains drops for the current day.


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