No Internet from WIFI connection on Router from 2nd LAN subnet

Jan 16, 2020, 3:36 PM

On pfSense DHCP logs, I see "3 bad IP checksums seen in 5 packets"

Jan 16 06:57:11 dhcrelay Listening on BPF/ix2/a0:36:9f:1a:4c:6c
Jan 16 06:57:11 dhcrelay Sending on BPF/ix2/a0:36:9f:1a:4c:6c
Jan 16 06:57:11 dhcrelay Listening on BPF/ix3/a0:36:9f:1a:4c:6e
Jan 16 06:57:11 dhcrelay Sending on BPF/ix3/a0:36:9f:1a:4c:6e
Jan 16 06:57:11 dhcrelay Sending on Socket/fallback
Jan 16 06:58:13 dhcrelay 3 bad IP checksums seen in 5 packets
Jan 16 06:58:51 dhcrelay 3 bad IP checksums seen in 5 packets
Jan 16 06:59:30 dhcrelay 3 bad IP checksums seen in 5 packets
Jan 16 07:00:09 dhcrelay 3 bad IP checksums seen in 5 packets
Jan 16 07:00:46 dhcrelay 3 bad IP checksums seen in 5 packets
Jan 16 07:01:24 dhcrelay 3 bad IP checksums seen in 5 packets
Jan 16 07:27:07 dhcrelay 3 bad IP checksums seen in 5 packets

I also tried connecting a laptop directly to the asus router and dhcp logs give same message as above.

Not sure what that means! I'll try googling it.

stephenw10 · Jan 16, 2020, 3:38 PM

Try disabling 'Hardware Checksum Offloading' in System > Advanced > Networking. You may need to reboot to apply that change.

Nothing showing as blocked in the firewall log though?

Steve

Jan 16, 2020, 3:40 PM

@stephenw10 Okay, i'll try that right now!

Sorry, in my firewall logs I see:

🔒 Log in to view

stephenw10 · Jan 16, 2020, 3:47 PM

You might have to filter that for only udp destination port 67 on the devices LAN. That only shows 12s of logs so you could easily miss connection attempts otherwise.

Steve

Jan 16, 2020, 3:50 PM

@stephenw10 I disabled "Hardware Checksum Offloading" and DHCP logs are no longer getting the "3 bad IP checksums seen in 5 packets" error. But no IP from DHCP still.

Jan 16, 2020, 4:03 PM

@stephenw10 I'm getting "No logs to display" or did I do the filter wrong? Not sure if/what I need to put in source and destination IP.

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stephenw10 · Jan 16, 2020, 4:09 PM

That looks correct, you should see blocked dhcp traffic there if was being blocked.

Check for port 67 states when the client is trying to connect in the state table. In Diag > States filter by :67, you will have to refresh that to see them.

Steve

Jan 16, 2020, 4:13 PM

Okay!

Please see below for Diag > States filtered by :67

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10.1.10.8 is my DHCP server

stephenw10 · Jan 16, 2020, 4:20 PM

Hmm, yet no state on DEVICES_LAN.... the client was definitely trying to connect at that point?

Jan 16, 2020, 4:23 PM

@stephenw10 Yeet! Sorry, I mis-understood.

Nothing was trying to connect at that moment I did the filter.

I re-did it when my phone was trying to connect to wifi:

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Jan 16, 2020, 4:25 PM

@stephenw10 Here is one of my laptop, directly connected to the asus router with ethernet:

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stephenw10 · Jan 16, 2020, 4:58 PM

Hmm, that looks correct in terms of open states. But nothing going back to the client. Anything logged on the server?

Might have to pcap on LAN filtered by the server IP to see if the requests are actually going to it.

Steve

Jan 16, 2020, 5:33 PM

:(

Here is packet capture that I did on pfSense when my phone was trying to connect to wifi:

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09:29:42.457022 IP (tos 0x0, ttl 64, id 43572, offset 0, flags [none], proto UDP (17), length 328)
10.1.10.1.67 > 10.1.10.8.67: [udp sum ok] BOOTP/DHCP, Request from fe:3d:88:34:f1:48, length 300, hops 1, xid 0x14fd712, secs 5, Flags [none] (0x0000)
Gateway-IP 10.1.13.1
Client-Ethernet-Address fe:3d:88:34:f1:48
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether fe:3d:88:34:f1:48
MSZ Option 57, length 2: 1500
Vendor-Class Option 60, length 15: "android-dhcp-10"
Parameter-Request Option 55, length 10:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name
MTU, BR, Lease-Time, RN
RB, Vendor-Option
Agent-Information Option 82, length 5:
Circuit-ID SubOption 1, length 3: ix2
09:29:47.474145 IP (tos 0x0, ttl 64, id 11403, offset 0, flags [none], proto UDP (17), length 328)
10.1.10.1.67 > 10.1.10.8.67: [udp sum ok] BOOTP/DHCP, Request from fe:3d:88:34:f1:48, length 300, hops 1, xid 0x14fd712, secs 10, Flags [none] (0x0000)
Gateway-IP 10.1.13.1
Client-Ethernet-Address fe:3d:88:34:f1:48
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether fe:3d:88:34:f1:48
MSZ Option 57, length 2: 1500
Vendor-Class Option 60, length 15: "android-dhcp-10"
Parameter-Request Option 55, length 10:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name
MTU, BR, Lease-Time, RN
RB, Vendor-Option
Agent-Information Option 82, length 5:
Circuit-ID SubOption 1, length 3: ix2
09:29:47.635729 IP (tos 0x0, ttl 128, id 5587, offset 0, flags [none], proto UDP (17), length 82)
10.1.10.8.58751 > 10.1.10.1.53: [udp sum ok] 55300+ [1au] A? eus-oi-ods-b.cloudapp.net. ar: . OPT UDPsize=4000 (54)
09:29:47.650479 IP (tos 0x0, ttl 64, id 4119, offset 0, flags [none], proto UDP (17), length 98)
10.1.10.1.53 > 10.1.10.8.58751: [udp sum ok] 55300 q: A? eus-oi-ods-b.cloudapp.net. 1/0/1 eus-oi-ods-b.cloudapp.net. A 40.79.154.85 ar: . OPT UDPsize=4096 (70)
09:29:55.696010 IP (tos 0x0, ttl 64, id 26722, offset 0, flags [none], proto UDP (17), length 328)
10.1.10.1.67 > 10.1.10.8.67: [udp sum ok] BOOTP/DHCP, Request from fe:3d:88:34:f1:48, length 300, hops 1, xid 0x14fd712, secs 18, Flags [none] (0x0000)
Gateway-IP 10.1.13.1
Client-Ethernet-Address fe:3d:88:34:f1:48
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether fe:3d:88:34:f1:48
MSZ Option 57, length 2: 1500
Vendor-Class Option 60, length 15: "android-dhcp-10"
Parameter-Request Option 55, length 10:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name
MTU, BR, Lease-Time, RN
RB, Vendor-Option
Agent-Information Option 82, length 5:
Circuit-ID SubOption 1, length 3: ix2
09:30:12.750834 IP (tos 0x0, ttl 64, id 41397, offset 0, flags [none], proto UDP (17), length 328)
10.1.10.1.67 > 10.1.10.8.67: [udp sum ok] BOOTP/DHCP, Request from fe:3d:88:34:f1:48, length 300, hops 1, xid 0x14fd712, secs 35, Flags [none] (0x0000)
Gateway-IP 10.1.13.1
Client-Ethernet-Address fe:3d:88:34:f1:48
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether fe:3d:88:34:f1:48
MSZ Option 57, length 2: 1500
Vendor-Class Option 60, length 15: "android-dhcp-10"
Parameter-Request Option 55, length 10:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name
MTU, BR, Lease-Time, RN
RB, Vendor-Option
Agent-Information Option 82, length 5:
Circuit-ID SubOption 1, length 3: ix2
09:30:16.207646 IP (tos 0x0, ttl 64, id 38410, offset 0, flags [none], proto UDP (17), length 328)
10.1.10.1.67 > 10.1.10.8.67: [udp sum ok] BOOTP/DHCP, Request from fe:3d:88:34:f1:48, length 300, hops 1, xid 0xa26f2a53, Flags [none] (0x0000)
Gateway-IP 10.1.13.1
Client-Ethernet-Address fe:3d:88:34:f1:48
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether fe:3d:88:34:f1:48
MSZ Option 57, length 2: 1500
Vendor-Class Option 60, length 15: "android-dhcp-10"
Parameter-Request Option 55, length 10:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name
MTU, BR, Lease-Time, RN
RB, Vendor-Option
Agent-Information Option 82, length 5:
Circuit-ID SubOption 1, length 3: ix2
09:30:21.213556 IP (tos 0x0, ttl 64, id 60954, offset 0, flags [none], proto UDP (17), length 328)
10.1.10.1.67 > 10.1.10.8.67: [udp sum ok] BOOTP/DHCP, Request from fe:3d:88:34:f1:48, length 300, hops 1, xid 0xa26f2a53, secs 5, Flags [none] (0x0000)
Gateway-IP 10.1.13.1
Client-Ethernet-Address fe:3d:88:34:f1:48
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether fe:3d:88:34:f1:48
MSZ Option 57, length 2: 1500
Vendor-Class Option 60, length 15: "android-dhcp-10"
Parameter-Request Option 55, length 10:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name
MTU, BR, Lease-Time, RN
RB, Vendor-Option
Agent-Information Option 82, length 5:
Circuit-ID SubOption 1, length 3: ix2
09:30:25.183289 IP (tos 0x0, ttl 64, id 56349, offset 0, flags [none], proto UDP (17), length 328)
10.1.10.1.67 > 10.1.10.8.67: [udp sum ok] BOOTP/DHCP, Request from fe:3d:88:34:f1:48, length 300, hops 1, xid 0xa26f2a53, secs 8, Flags [none] (0x0000)
Gateway-IP 10.1.13.1
Client-Ethernet-Address fe:3d:88:34:f1:48
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether fe:3d:88:34:f1:48
MSZ Option 57, length 2: 1500
Vendor-Class Option 60, length 15: "android-dhcp-10"
Parameter-Request Option 55, length 10:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name
MTU, BR, Lease-Time, RN
RB, Vendor-Option
Agent-Information Option 82, length 5:
Circuit-ID SubOption 1, length 3: ix2
09:30:32.659175 IP (tos 0x0, ttl 64, id 38685, offset 0, flags [none], proto UDP (17), length 328)
10.1.10.1.67 > 10.1.10.8.67: [udp sum ok] BOOTP/DHCP, Request from fe:3d:88:34:f1:48, length 300, hops 1, xid 0xa26f2a53, secs 16, Flags [none] (0x0000)
Gateway-IP 10.1.13.1
Client-Ethernet-Address fe:3d:88:34:f1:48
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Discover
Client-ID Option 61, length 7: ether fe:3d:88:34:f1:48
MSZ Option 57, length 2: 1500
Vendor-Class Option 60, length 15: "android-dhcp-10"
Parameter-Request Option 55, length 10:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name
MTU, BR, Lease-Time, RN
RB, Vendor-Option
Agent-Information Option 82, length 5:
Circuit-ID SubOption 1, length 3: ix2

stephenw10 · Jan 16, 2020, 7:21 PM

Ok so no replies from the DHCP server back to the client. Either the server is not able to respond or it's refusing to respond.

Steve

Jan 16, 2020, 7:26 PM

@stephenw10 Interesting, not sure what the issue is but I guess i'll have to do some digging..

Thank you for your help! I will update when/if I find anything.

Jan 16, 2020, 7:34 PM

@techgeek055 Wow, I found the issue. I removed my default gateway on the NIC interface on my Windows DHCP server a while back. I did this so that it had no internet connection for security.

Once I added the default gateway back to point to my pfsense box , I am getting IP from DHCP on my other subnet.

Do you know what would be the "proper" way of taking the server off the internet while not breaking DHCP for other subnets?

stephenw10 · Jan 16, 2020, 7:45 PM

Ah, nice. So it had no route back to 10.1.13.0/24.

You should be able to just add that as a permanent route on the Windows server rather than adding a default route.
So add 10.1.13.0/24 via 10.1.10.1.
It will still have no default route so no way to reach external IPs.

Or you could just block that traffic in pfSense.

Steve

Jan 16, 2020, 8:02 PM

Sweet, that worked! I opened command prompt on the windows server and entered:

route add /p 10.1.13.0 mask 255.255.255.0 10.1.10.1

Thank you sooooooooo much! You guys are so awesome.

Now that I fixed this issue, I can attempt VLANs again! Yahooo!

marvosa · Jan 16, 2020, 9:02 PM

I would've gone the firewall route as a safeguard to any future design changes and/or misconfigurations. The firewall route would also generate records of all internet attempts by the server for better auditing/troubleshooting. While a persistent route on the server does accomplish your short term goal... it just doesn't scale well.

As a reminder to yourself, I would definitely document somewhere the fact that a persistent route exists on the server... or at some point...6 months, 1 year, 2 years, etc from now... you'll forget and it may come back to haunt you as your network design evolves and your needs/priorities change.

Jan 16, 2020, 8:48 PM

That's a good point. On second thought, i think I may go the firewall route. I've already documented the route for future reference!

Thank you very much for your assistance in this frustrating issue I had!

Till we meet again!