Home / ubuntu / Questions / 445186
Accepted
Paulo Coghi
Asked: 2014-04-09 13:07:51 +0800 CST

How to check current MTU value

  • 772

How can I check the MTU value for my current connection?

In my network connection settings, the MTU is set to automatic and I would like to know wich value was automatic selected for it.

networking

3 Answers

  1. Best Answer
    ifconfig

    to view the current MTU. Example (just searching for MTU):

    ifconfig| grep -i MTU
      UP BROADCAST MULTICAST  MTU:1500  Metric:1
      UP LOOPBACK RUNNING  MTU:65536  Metric:1
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
    • 52

  2. Alternative method:

    ip addr | grep mtu

    For example:

     ip addr | grep mtu
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
2: enp0s31f6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1300 qdisc fq_codel state UP group default qlen 1000
3: wlp4s0: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN group default qlen 1000
4: veth0@if5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1400 qdisc noqueue state UP group default qlen 1000
    • 46

  3. You can read the value from the /sys kernel file system:

    cat /sys/class/net/<interface>/mtu

    Replace <interface> with the name of the interface to query.

    • 24