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Accepted
Mike
Asked: 2010-10-29 09:55:17 +0800 CST

Monitor number of bytes transferred to/from IP address on port

  • 772

Can anyone recommend a linux command line tool to monitor the number of bytes transferred between the local server and a specified IP address/port.

The equivalent tcpdump command would be:

tcpdump -s 0 -i any -w mycapture.trc port 80 host google.com

which outputs :

46 packets captured
131 packets received by filter
0 packets dropped by kernel

I'd like something similar that outputs:

54 bytes out, 176 bytes in

I'd like it to work on RHEL and be free/open-source. It would be good if there was an existing tool which I was just missing too!

linux tcpdump packet-analyzer tshark packet-capture

4 Answers

  1. Best Answer

    You could use iptables. If you're not already using it, you can use an open Accept configuration, but have a rule in place to do the counting.

    For example, on RHEL your /etc/sysconfig/iptables file could look something like:

    *filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A FORWARD -j INPUT
-A INPUT -s 10.10.1.1 -p tcp -m tcp --sport 80 -j ACCEPT
-A OUTPUT -d 10.10.1.1 -p tcp -m tcp --dport 80 -j ACCEPT

    Where 10.10.1.1:80 is the host:port you want to count traffic to (you can't use a hostname). You can then check traffic counted with the command iptables -nvxL as root.

    Example output:

    Chain INPUT (policy ACCEPT 7133268 packets, 1057227727 bytes)
    pkts      bytes target     prot opt in     out     source               destination     
 7133268 1057227727 ACCEPT     tcp  --  *      *       10.10.1.1            0.0.0.0/0              tcp spt:80


Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
    pkts      bytes target     prot opt in     out     source               destination     
       0          0 INPUT      all  --  *      *       0.0.0.0/0            0.0.0.0/0       

Chain OUTPUT (policy ACCEPT 7133268 packets, 1057227727 bytes)
    pkts      bytes target     prot opt in     out     source               destination     
 7133268 1057227727 ACCEPT     tcp  --  *      *       0.0.0.0/0            10.10.1.1              tcp dpt:80
    • 15

  2. I was about to suggest wireshark (for it's many 'conversation' features), but it is not a command-line tool. You could try tshark though, which is a command-line analyzer tool that is closes to wireshark. The output should have (somewhat) what you're looking for (example below):

    tshark -R "ip.addr == 10.2.3.67" -z conv,ip -p -f "tcp port 22"

    Result:

                                         |       <-      | |       ->      | |     Total     |
                                     | Frames  Bytes | | Frames  Bytes | | Frames  Bytes |
10.2.3.23           <-> 10.2.3.67        42     15341      35      4890      77     20231
    • 10

  3. There is also a tool called 'iftop' which displays bandwidth usage on an interface by host. I think iftop can do what you described but normally its interface is something like 'top'.

    So for your example, I think that you can just create config file to provide your filter-code.

    So here is my filter-code in my config file.

    $ cat /tmp/conf
filter-code: port http and host google.com

    Then, I ran the following to see the network traffice.

    $ sudo iftop -c /tmp/conf

    Not sure if this is the best option but certainly one way to achieve what you need. HTH.

    • 7

  4. You can also try "iptraf" it's lightweight and simple. It can filter by port and gives you high level info, no payload data, etc.

    • 3