On Sun, Jul 22, 2012 at 5:18 PM, Joe <j...@jretrading.com> wrote: > On Sun, 22 Jul 2012 16:44:13 +0800 > lina <lina.lastn...@gmail.com> wrote: > >> >> Checked, now only 22 80 open with 443 closed. >> another thing is that the nmap can scan my MAC address correctly. >> is it bad? (I guess I will feel comfortable if the MAC address is >> hidden) >> > > All network communication is actually based on MAC addresses, if it > can't be seen, you can't talk. > > Try arp -a as root to see what other computers yours has recently > talked to. A cache is kept to speed things up, but only for a few > minutes, otherwise your computer has to broadcast to look up a link > between IP address and MAC. Thanks, packet looks for the IP address first or MAC address first? (seems I read something before, it's a book/document written in 2001, kinda of aged? still don't understand.) > > If you have a rainy afternoon to while away, install Wireshark and have > a play with it. Try various network connections while a capture is > running, and play with the filtering. One day you will need to use it > in anger. (Here "in anger", you implied that the wireshark was not so much fun to play with? just curious... I installed but never see how can it be useful, or mainly I don't know what/how to check among so much information it popped up.) > > Here is a fragment of a capture showing my workstation trying to find > the server using the ARP protocol. It hasn't connected for a time, so > the server isn't in its cache: > > No. Time Source Destination Protocol Length Info > > 5 5.007111000 Giga-Byt_xx:xx:xx Hewlett-_xx:xx:xx ARP 42 > Who has 192.168.99.3? Tell 192.168.99.101 > > 6 5.007315000 Hewlett-_xx:xx:xx Giga-Byt_xx:xx:xx ARP 60 > 192.168.99.3 is at xx:xx:xx:xx:xx:xx > > Sorry about the wrap, but email isn't designed for this sort of thing. > Note that the first half of the MAC is a vendor ID, and Wireshark > decodes it.
Thank you. I will do a try, Best regards, > > -- > Joe > > > -- > To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org > with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org > Archive: http://lists.debian.org/20120722101816.4e778...@jretrading.com > -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/cag9cjmk2cbbn6s7ujmddt1odc0sxr1p19u75gktd9k79mbw...@mail.gmail.com
