windows: vista slow network

we've been having slow network traffic on vista PCs connected to our network. to try to resolve we disabled their IPv6 interfaces. we're not using them anyway.

so far their network connection has been more stable.

among other things we tried, we adjusted their network speeds and restarted and even replaced network switches.

linux: pcap (packet capture) using tcpdump

to capture network packets traffic using tcpdump...

dump and save traffic of network on file:
# tcpdump -w <filename> -i <network interface> -s 0
ex. # tcpdump -w host.pcap -i eth0 -s 0

note: "-s 0" parameter is for capturing all of the response and not do a "S"nap
note too: you can use '((tcp) and (port 80))' to only dump communication using tcp protocol on port 80
ex. # tcpdump -w host.pcap -i eth0 '((tcp) and (port 80))' -s 0

read dump file:
# tcpdump -ttttnr <filename>

(source/s: http://bikulov.org/post/34917160303/tools-for-tracing-a-pcap-file-in-linux-bash, http://quimicefa.wordpress.com/2009/07/16/tcpdump-%E2%80%93-packet-size-limited-during-capture-eng/)

i recently used this to show successful communication between hosts, making sure packets are sent and received.

ps. if you're using wireshark to view your pcap file, filtering by source and destination ip helped me find specific tcp streams (Filter: ip.src==<ip> or ip.dst==<ip>)

linux: network usage with iftop

been experiencing network slowdown in our LAN these past months and have been guessing what's eating the bandwidth. found a tool named iftop a couple of weeks ago that displays network bandwidth usage. you can get it from: http://pkgs.repoforge.org/iftop/

to launch, run: # iftop
press h to toggle help

here's a sample of what it can show:

now network hugging users can be identified ;)

linux: adjusting network speed using mii-tool

i started my machine on linux (Ubuntu 11.04 - Natty Narwhal) and noticed its very slow browsing speed. i remembered this problem i have when connected to this specific network wherein i have to change my network speed to get better connection.

how do you change your network speed on linux? i use mii-tool

first, i did a test ping which showed 20% packet loss

next, i checked my current network speed setting

then, i set my network speed to 10mbps and redid a test ping

tada! 0% packet loss!

now i have to figure out why my machine wouldn't budge on this network using 100mbps.