How to monitor bandwidth on a Linux router by LAN IP

Question

There are plenty of ways to monitor traffic on a specific interface or even by port. But if I am on a router and suspect one of the workstations is using more bandwidth then others, how to check?

Solution 1

iftop will show the TCP/UDP streams on an interface in realtime, which is often sufficient to identify which host is hogging the bandwidth. If you want something to record this over time, try darkstat or bandwidthd.

Solution 2

iftop can do this and it's easily apt-get'able:

             191Mb      381Mb                 572Mb       763Mb             954Mb     
└────────────┴──────────┴─────────────────────┴───────────┴──────────────────────
box4.local            => box-2.local                      91.0Mb  27.0Mb  15.1Mb
                      <=                                  1.59Mb   761kb   452kb
box4.local            => box.local                         560b   26.8kb  27.7kb
                      <=                                   880b   31.3kb  32.1kb
box4.local            => userify.com                         0b   11.4kb  8.01kb
                      <=                                  1.17kb  2.39kb  1.75kb
box4.local            => b.resolvers.Level3.net              0b     58b    168b
                      <=                                     0b     83b    288b
box4.local            => stackoverflow.com                   0b     42b     21b
                      <=                                     0b     42b     21b
box4.local            => 224.0.0.251                         0b      0b    179b
                      <=                                     0b      0b      0b
224.0.0.251           => box-2.local                         0b      0b      0b
                      <=                                     0b      0b     36b
224.0.0.251           => box.local                           0b      0b      0b
                      <=                                     0b      0b     35b


─────────────────────────────────────────────────────────────────────────────────
TX:           cum:   37.9MB   peak:   91.0Mb     rates:   91.0Mb  27.1Mb  15.2Mb
RX:                  1.19MB           1.89Mb              1.59Mb   795kb   486kb
TOTAL:               39.1MB           92.6Mb              92.6Mb  27.9Mb  15.6Mb

nload is another great tool for monitoring bandwidth in real time, also in the repos, but can't sort by specific destination IP:

Device eth0 [10.10.10.5] (1/2):
=====================================================================================
Incoming:


                               .         ...|    
                               #         ####|   
                           .. |#|  ...   #####.         ..          Curr: 2.07 MBit/s
                          ###.###  #### #######|.     . ##      |   Avg: 1.41 MBit/s
                         ########|#########################.   ###  Min: 1.12 kBit/s
             ........    ###################################  .###  Max: 4.49 MBit/s
           .##########. |###################################|#####  Ttl: 1.94 GByte
Outgoing:
            ##########  ###########    ###########################
            ##########  ###########    ###########################
            ##########. ###########   .###########################
            ########### ###########  #############################
            ########### ###########..#############################
           ############ ##########################################
           ############ ##########################################
           ############ ##########################################  Curr: 63.88 MBit/s
           ############ ##########################################  Avg: 32.04 MBit/s
           ############ ##########################################  Min: 0.00 Bit/s
           ############ ##########################################  Max: 93.23 MBit/s
         ############## ##########################################  Ttl: 2.49 GByte

For automated usage, don't forget about the classic sar and netstat on older *nix and combining with cut, grep, and awk.

Comments

[Alex]

Thank you, any way to monitor across multiple interfaces? either with iftop or similar?

[mgorven]

Looks like you have to run an iftop per interface.