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How dynamic are eircom fibre IPs?

  • 06-11-2013 1:53am
    #1
    sdanseo
    Registered Users, Registered Users 2 Posts: 9,234 ✭✭✭


    I do a bit of admin work on an online gaming community and IP security isn't particularly tight, so I've been hit with DDOS attack a few times recently.

    Wondering if the problem surrounding UPC IPs not changing when you reset the modem could be best sorted by switcing back to the devil I know? Does an eircom eFibre IP definitely change as soon as you reset the modem or is the DHCP lease also impossibly long?


Comments

  • #2
    Bog Standard User
    Registered Users, Registered Users 2 Posts: 847 ✭✭✭Bog Standard User


    sdeire wrote: »
    I do a bit of admin work on an online gaming community and IP security isn't particularly tight, so I've been hit with DDOS attack a few times recently.

    Wondering if the problem surrounding UPC IPs not changing when you reset the modem could be best sorted by switcing back to the devil I know? Does an eircom eFibre IP definitely change as soon as you reset the modem or is the DHCP lease also impossibly long?

    to change your ip on eircom efibre turn off the modem for at least 15 minutes then switch it back on... it will get a new ip address then.

    if an efibre modem is power cycled (turned off and back on with in 15 mins it will get the same ip address again)

    if you are getting ddos attacks from a specific ip address note the mac address of that modem then block it by mac address... then that modem will not be able to ddos attack your site regardless of what ip address it has


  • #3
    MrO
    Registered Users Posts: 193 ✭✭MrO


    Bog Standard User wrote: »
    if you are getting ddos attacks from a specific ip address note the mac address of that modem then block it by mac address... then that modem will not be able to ddos attack your site regardless of what ip address it has

    Does that work? I didn't think you could resolve the mac address of a remote device i.e. something outside of your local lan


  • #4
    Bog Standard User
    Registered Users, Registered Users 2 Posts: 847 ✭✭✭Bog Standard User


    MrO wrote: »
    Does that work? I didn't think you could resolve the mac address of a remote device i.e. something outside of your local lan

    yes if a pc on any router makes a connection to your server you can trace it back. once you get the mac address of the router you can block any traffic that comes through that router to your server.



    you could find it using packet sniffers


  • #5
    MrO
    Registered Users Posts: 193 ✭✭MrO


    Bog Standard User wrote: »
    yes if a pc on any router makes a connection to your server you can trace it back. once you get the mac address of the router you can block any traffic that comes through that router to your server.



    Try nbtstat -a in the command prompt, it give you the mac address of the remote computer


    That's only if the device is on the same subnet as you (unlikely in the case of D-DOS attack).

    As I understand it mac-addresses don't really have a function outside of the link layer. Everytime an ethernet frame encounters a layer 3 device the frame is stripped away, routing lookups are done and the ethernet frame is rebuilt for forwarding (new source and destination mac addresses).


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