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Firewall Selectively dropping DHCP on a single vlan interface with rule_id=0

Hi,

I implemented a new network and set DHCP up on it. I have a wired device that gets DHCP all of the time and a wireless device that is rejected by rule_id_0 every time.

2018-04-13 05:08:45Firewallmessageid="02002" log_type="Firewall" log_component="Appliance Access" log_subtype="Denied" status="Deny" con_duration="0" fw_rule_id="0" policy_type="0" user="" user_group="" web_policy_id="0" ips_policy_id="0" appfilter_policy_id="0" app_name="" app_risk="0" app_technology="" app_category="" in_interface="Port4.255" out_interface="" src_mac="98:22:ef:dc:c6:9f" src_ip="0.0.0.0" src_country="" dst_ip="255.255.255.255" dst_country="" protocol="UDP" src_port="68" dst_port="67" packets_sent="0" packets_received="0" bytes_sent="0" bytes_received="0" src_trans_ip="" src_trans_port="0" dst_trans_ip="" dst_trans_port="0" src_zone_type="" src_zone="" dst_zone_type="" dst_zone="" con_direction="" con_id="" virt_con_id="" hb_status="No Heartbeat" message="" appresolvedby="Signature"

I do not even have a firewall rule_id 0 that is visible from the GUI, but from what I gather - it is built in somewhere.

Does someone know why this happens? Successful device first, failure second.. (capture from Sophos)

Success::

tcpdump: 05:04:08.541151 Port4.255, IN: IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 70:88:6b:8f:45:98, length 300, xid 0xd74be678, secs 6, Flags [none]
      Client-Ethernet-Address 70:88:6b:8f:45:98
      Vendor-rfc1048 Extensions
        Magic Cookie 0x63825363
        DHCP-Message Option 53, length 1: Request
        Requested-IP Option 50, length 4: 192.168.255.101
        Parameter-Request Option 55, length 18:
          Subnet-Mask, BR, Time-Zone, Classless-Static-Route
          Domain-Name, Domain-Name-Server, Hostname, YD
          YS, NTP, MTU, Option 119
          Default-Gateway, Classless-Static-Route, Classless-Static-Route-Microsoft, Static-Route
          Option 252, NTP
        Client-ID Option 61, length 23: hardware-type 255, 6b:8f:45:98:00:04:ff:93:53:e8:0f:ea:43:93:bb:0f:d7:94:41:60:9a:c5
   0x0000: ffff ffff ffff 7088 6b8f 4598 0800 4510 ......p.k.E...E.
   0x0010: 0148 0000 0000 8011 3996 0000 0000 ffff .H......9.......
   0x0020: ffff 0044 0043 0134 f9eb 0101 0600 d74b ...D.C.4.......K
   0x0030: e678 0006 0000 0000 0000 0000 0000 0000 .x..............
   0x0040: 0000 0000 0000 7088 6b8f 4598 0000 0000 ......p.k.E.....
   0x0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0060: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0070: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0080: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0090: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0100: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0110: 0000 0000 0000 6382 5363 3501 0332 04c0 ......c.Sc5..2..
   0x0120: a8ff 6537 1201 1c02 790f 060c 2829 2a1a ..e7....y...()*.
   0x0130: 7703 79f9 21fc 2a3d 17ff 6b8f 4598 0004 w.y.!.*=..k.E...
   0x0140: ff93 53e8 0fea 4393 bb0f d794 4160 9ac5 ..S...C.....A`..
   0x0150: ff00 0000 0000                           ......
05:04:08.541380 Port4.255, OUT: IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    192.168.255.1.67 > 192.168.255.101.68: BOOTP/DHCP, Reply, length 300, xid 0xd74be678, secs 6, Flags [none]
      Your-IP 192.168.255.101
      Client-Ethernet-Address 70:88:6b:8f:45:98
      Vendor-rfc1048 Extensions
        Magic Cookie 0x63825363
        DHCP-Message Option 53, length 1: ACK
        Server-ID Option 54, length 4: 192.168.255.1
        Lease-Time Option 51, length 4: 85839
        Subnet-Mask Option 1, length 4: 255.255.255.0
        Domain-Name Option 15, length 12: "homeunix.com"
        Domain-Name-Server Option 6, length 4: 192.168.255.1
        Default-Gateway Option 3, length 4: 192.168.255.1
   0x0000: 7088 6b8f 4598 00ec accf 0043 0800 4510 p.k.E......C..E.
   0x0010: 0148 0000 0000 8011 b9dc c0a8 ff01 c0a8 .H..............
   0x0020: ff65 0043 0044 0134 e573 0201 0600 d74b .e.C.D.4.s.....K
   0x0030: e678 0006 0000 0000 0000 c0a8 ff65 0000 .x...........e..
   0x0040: 0000 0000 0000 7088 6b8f 4598 0000 0000 ......p.k.E.....
   0x0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0060: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0070: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0080: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0090: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0100: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0110: 0000 0000 0000 6382 5363 3501 0536 04c0 ......c.Sc5..6..
   0x0120: a8ff 0133 0400 014f 4f01 04ff ffff 000f ...3...OO.......
   0x0130: 0c68 6f6d 6575 6e69 782e 636f 6d06 04c0 .homeunix.com...
   0x0140: a8ff 0103 04c0 a8ff 01ff 0000 0000 0000 ................
   0x0150: 0000 0000 0000                           ......
05:04:14.490943 Port4.255, IN: IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 70:88:6b:8f:45:98, length 300, xid 0x29324d7d, Flags [none]
      Client-Ethernet-Address 70:88:6b:8f:45:98
      Vendor-rfc1048 Extensions
        Magic Cookie 0x63825363
        DHCP-Message Option 53, length 1: Request
        Requested-IP Option 50, length 4: 192.168.255.101
        Parameter-Request Option 55, length 18:
          Subnet-Mask, BR, Time-Zone, Classless-Static-Route
          Domain-Name, Domain-Name-Server, Hostname, YD
          YS, NTP, MTU, Option 119
          Default-Gateway, Classless-Static-Route, Classless-Static-Route-Microsoft, Static-Route
          Option 252, NTP
        Client-ID Option 61, length 23: hardware-type 255, 6b:8f:45:98:00:04:ff:93:53:e8:0f:ea:43:93:bb:0f:d7:94:41:60:9a:c5
   0x0000: ffff ffff ffff 7088 6b8f 4598 0800 4510 ......p.k.E...E.
   0x0010: 0148 0000 0000 8011 3996 0000 0000 ffff .H......9.......
   0x0020: ffff 0044 0043 0134 4107 0101 0600 2932 ...D.C.4A.....)2
   0x0030: 4d7d 0000 0000 0000 0000 0000 0000 0000 M}..............
   0x0040: 0000 0000 0000 7088 6b8f 4598 0000 0000 ......p.k.E.....
   0x0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0060: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0070: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0080: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0090: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0100: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0110: 0000 0000 0000 6382 5363 3501 0332 04c0 ......c.Sc5..2..
   0x0120: a8ff 6537 1201 1c02 790f 060c 2829 2a1a ..e7....y...()*.
   0x0130: 7703 79f9 21fc 2a3d 17ff 6b8f 4598 0004 w.y.!.*=..k.E...
   0x0140: ff93 53e8 0fea 4393 bb0f d794 4160 9ac5 ..S...C.....A`..
   0x0150: ff00 0000 0000                           ......
05:04:14.491088 Port4.255, OUT: IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    192.168.255.1.67 > 192.168.255.101.68: BOOTP/DHCP, Reply, length 300, xid 0x29324d7d, Flags [none]
      Your-IP 192.168.255.101
      Client-Ethernet-Address 70:88:6b:8f:45:98
      Vendor-rfc1048 Extensions
        Magic Cookie 0x63825363
        DHCP-Message Option 53, length 1: ACK
        Server-ID Option 54, length 4: 192.168.255.1
        Lease-Time Option 51, length 4: 85833
        Subnet-Mask Option 1, length 4: 255.255.255.0
        Domain-Name Option 15, length 12: "homeunix.com"
        Domain-Name-Server Option 6, length 4: 192.168.255.1
        Default-Gateway Option 3, length 4: 192.168.255.1
   0x0000: 7088 6b8f 4598 00ec accf 0043 0800 4510 p.k.E......C..E.
   0x0010: 0148 0000 0000 8011 b9dc c0a8 ff01 c0a8 .H..............
   0x0020: ff65 0043 0044 0134 328f 0201 0600 2932 .e.C.D.42.....)2
   0x0030: 4d7d 0000 0000 0000 0000 c0a8 ff65 0000 M}...........e..
   0x0040: 0000 0000 0000 7088 6b8f 4598 0000 0000 ......p.k.E.....
   0x0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0060: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0070: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0080: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0090: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0100: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0110: 0000 0000 0000 6382 5363 3501 0536 04c0 ......c.Sc5..6..
   0x0120: a8ff 0133 0400 014f 4901 04ff ffff 000f ...3...OI.......
   0x0130: 0c68 6f6d 6575 6e69 782e 636f 6d06 04c0 .homeunix.com...
   0x0140: a8ff 0103 04c0 a8ff 01ff 0000 0000 0000 ................
   0x0150: 0000 0000 0000                           ......

Failure::

tcpdump: 05:08:18.991129 Port4.255, IN: IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 98:22:ef:dc:c6:9f, length 300, xid 0x5a01a844, Flags [none]
      Client-Ethernet-Address 98:22:ef:dc:c6:9f
      Vendor-rfc1048 Extensions
        Magic Cookie 0x63825363
        DHCP-Message Option 53, length 1: Discover
        Parameter-Request Option 55, length 18:
          Subnet-Mask, BR, Time-Zone, Classless-Static-Route
          Domain-Name, Domain-Name-Server, Hostname, YD
          YS, NTP, MTU, Option 119
          Default-Gateway, Classless-Static-Route, Classless-Static-Route-Microsoft, Static-Route
          Option 252, NTP
        Client-ID Option 61, length 23: hardware-type 255, ef:dc:c6:9f:00:04:ff:93:53:e8:0f:ea:43:93:bb:0f:d7:94:41:60:9a:c5
   0x0000: ffff ffff ffff 9822 efdc c69f 0800 4510 ......."......E.
   0x0010: 0148 0000 0000 8011 3996 0000 0000 ffff .H......9.......
   0x0020: ffff 0044 0043 0134 981e 0101 0600 5a01 ...D.C.4......Z.
   0x0030: a844 0000 0000 0000 0000 0000 0000 0000 .D..............
   0x0040: 0000 0000 0000 9822 efdc c69f 0000 0000 ......."........
   0x0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0060: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0070: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0080: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0090: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x00f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0100: 0000 0000 0000 0000 0000 0000 0000 0000 ................
   0x0110: 0000 0000 0000 6382 5363 3501 0137 1201 ......c.Sc5..7..
   0x0120: 1c02 790f 060c 2829 2a1a 7703 79f9 21fc ..y...()*.w.y.!.
   0x0130: 2a3d 17ff efdc c69f 0004 ff93 53e8 0fea *=..........S...
   0x0140: 4393 bb0f d794 4160 9ac5 ff00 0000 0000 C.....A`........
   0x0150: 0000 0000 0000                           ......

Thanks for any insight!

-Greg

This thread was automatically locked due to age.

0 LuCar Toni over 7 years ago

Hi,

Thanks for the dump!

Do you use static DHCP mapping on XG?

Is 98:22:ef:dc:c6:9f used in the DHCP mapping?

Cheers
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0 Greg Oliver over 7 years ago in reply to LuCar Toni

This subnet has no static mappings, but another subnet has a static mapping for both devices included here.

I think this may be an issue with the cheap ass Zyxel switch I bought.

My setup is ISP router with all packets forwarded to Sophos on a direct connection (DMZ which moves the WAN IP to the DMZ host). Somehow, the DHCP request is also hitting the Sophos WAN port - which I assume is why it is dropping it. I di=o not see how since the WAN port on Sophos is not connected to the switch at all.

I am out for the wweekend, but will be looking at this again Sunday night and trying other thigs to narrrow it down. I do this type of stuff for a living, so will let you know how I solve it.

Thanks,

Greg
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0 Greg Oliver over 7 years ago in reply to Greg Oliver

Just getting to revisit this -

So like i figured the Zyxel switch (very cheap PoE+ switch for powering cameras and my APs), is sending out the port 67/68 traffic on both the vlan it came in on as well as the pvid.

Zyxel is going to make a new firmware (someday), but is there some way I can disable rule 0? I really do not like firewalls that do things behing my back anyhow, but if I can disable it temoprarily (or just the duplicate packet rule it is hitting), that is good for me.

Thanks,

Greg
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