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Thread: No IP from dhcpd with softAP/Airbase-ng

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  1. #1
    Just burned his ISO
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    Default No IP from dhcpd with softAP/Airbase-ng [PARTLY SOLVED]

    Hello,

    Before I'm losing my mind completely, I thought I should ask you about suggestions.

    I'm trying to set up an soft AP with my Alfa AWUS036H
    I'll start with a short description and we will see if someone already can pinpoint the problem from there. Otherwise I'm going to be more specific:

    • I put my Alfa-interace in monitor mode with airmon-ng
    • I start airbase-ng on the monitor interface
    • I have configured my dhcpd.conf file and told the dhcp-deamon to work on the tap interface which is newly created with command airbase
    • I set the IP on the tap interface (at0) to map to the correct IP which also is specified in dhcpd.conf as router and set the mtu to 1400 and bring up the at0-interface.
    • I add the correct route to the specified net with the gateway set to the same IP as I specified on at0.
    • I start the dhcpd and everything seems OK.
      ("Wrote 0 leases to leases file")


    From my other laptop I'm able to see the newly created AP and I can connect to it but I don't get an IP from dhcpd.
    If I run tcpdump on at0 the only thing I see is:
    "12:24.069960 TheClient'sMAC (oui Unknown) Null > Broadcast Unknown DSAP 0x08 Supervisory, Receiver not Ready, rcv seq 0, Flags [Command], length 330"

    What the h am I doing wrong? I am also able to see the client's request coming in:
    "12:24 Client TheClient'sMAC associated (unencrypted) to ESSID: "secret"

    I'm happy to give away all the conf-files and detailed descriptions, but I thought that I'll start with this light description and see if someone comes up with the solution or ideas.

    Thanks / Alex

  2. #2
    Just burned his ISO
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    Default

    The adapter I have is an Alfa 802.11g USB AWUS036H and I'm running backtrack 4 Final Release.

    Has anyone been able to set up an softAP (using dhcpd) with Bactrack 4 Final Release and Alfa AWUS036H/USB out of the box?

    I have tried different howtos but they all end up with the same problem. I can't get an IP from the DHCP-server on the laptop where airbase is also running.
    But I spot the AP and from the Airbase konsole I spot the client connect.

    Right now, I also observed this in the syslog:
    bt dhcpd: Wrote 0 leases to leases file.
    bt kernel: hpet1: lost 1 rtc interrupts


    Now when I got my hands on my girlfriend's Asus EEE notebook I was able to connect to the dhcp-service and get an correct IP address! (she wasn't as happy as I was)
    But the SSID only shows up with empty squares (unprintable characters i windows). And besides this it is very strange why my other laptop will not connect but her laptop will.

  3. #3
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    I'm so relieved.

    Applying the patch below did solve the issue with the weired SSID/empty squares (and an issue with the SSID filling up the client's list of available APs):
    hxxp://trac.aircrack-ng.org/ticket/714

    The question is if this changes anything with the problem I had with connecting from my other laptop? I'll try tomorrow, but doesn't it seems a bit unreasonable?

    Anyhow, the dhcpd service is working perfectly and the issue is with the source code to airbase-ng and the rtl8187 drivers.

  4. #4
    Junior Member FrankFruter's Avatar
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    dhcpd.conf
    Code:
    option domain-name-servers 10.0.0.1;
    
    default-lease-time 60;
    max-lease-time 72;
    
    ddns-update-style none;
    
    authoritative;
    
    log-facility local7;
    
    subnet 10.0.0.0 netmask 255.255.255.0 {
      range 10.0.0.100 10.0.0.254;
      option routers 10.0.0.1;
      option domain-name-servers 208.67.222.222, 208.67.220.220;
    }
    :cool::cool::cool::cool:

  5. #5
    Just burned his ISO
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    Well, thanks Mr FrankFruter but as I said there is no problem with my dhcp-config.

    I have now tested with my other laptop but I didn't manage to connect despite the patch (but from my girlfriend's laptop everything went smooth).

    But when I enabled WEP on the SoftAP it worked!! Now I can continue with my experiments but it would be nice in the future to be able to connect to the SoftAP from my DELL machine without any encryption.

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