XG210, SFOS 19.5.2 MR-2-Build624
So, I have two VLANs, VLAN 70 - 192.168.70.0/28 and VLAN 100 - 10.0.0.0/24. DHCP server is on VLAN100, I want to relay DHCP requests from VLAN70 to VLAN100 for service. I have a relay set up like so:
Name | ||
IP version |
IPv4
|
|
Interface | LAN70 - IoT - 192.168.70.1 | |
DHCP server IP |
|
|
Relay through IPsec | OFF |
The Sophos IP for VLAN 70 is 192.168.70.1, which is the gateway.
However, devices on VLAN70 are not getting DHCP via the XG relay, and I am seeing entries like this in the PCAP:
Time
|
In interface
|
Out interface
|
Ethernet type
|
Source IP
|
Destination IP
|
Packet type
|
Ports [src,dst]
|
NAT ID
|
Rule ID
|
Status
|
Reason
|
---|---|---|---|---|---|---|---|---|---|---|---|
2023-05-23 18:16:45
|
Port8.70
|
IPv4
|
0.0.0.0
|
255.255.255.255
|
UDP
|
68,67
|
0
|
0
|
Violation
|
Local_ACL
|
|
2023-05-23 18:16:45
|
Port8.70
|
IPv4
|
0.0.0.0
|
255.255.255.255
|
UDP
|
68,67
|
0
|
0
|
Incoming
|
||
2023-05-23 18:16:45
|
Port8.70
|
IPv4
|
0.0.0.0
|
255.255.255.255
|
UDP
|
68,67
|
0
|
0
|
Violation
|
Local_ACL
|
|
2023-05-23 18:16:45
|
Port8.70
|
IPv4
|
0.0.0.0
|
255.255.255.255
|
UDP
|
68,67
|
0
|
0
|
Incoming
|
I saw nothing saying firewall rules needed to be created to allow internal traffic between the VLANs on the DHCP service, but I created some - just in case - but that hasn't made any difference.
Anyone have any insight here? I have seen some similar threads, but they all seem to be trying to do DHCP over VPN/RED and/or had a relay setup on the VLAN with the DHCP server, neither of which is true in my case. If I set a device to a static IP within the subnet, things work fine, it's just the DHCP relay that isn't working.
Thanks in advance.
Hi Ryzen,
Thank you for reaching out to Sophos Community.
Have you tried to use any how-to videos, documentation, Sophos Assistant, or KBA to try to check the issue?
Can you try the following KB and update us if this might assist you.
https://support.sophos.com/support/s/article/KB-000038345?language=en_US
Erick Jan
Global Community Engineer, Support & Services
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Hi Erick , I searched the KB but couldn't find anything helpful. The article you linked just talks about DHCP forwarders when the DHCP server is in the same subnet, which I mentioned in my post, but does not apply to my situation. I only have one forwarder, and it's for a subnet that is separate from the DHCP server, as you can see from the settings.
Where is the relay set? If you are not using the XG as the DHCP server then there is nowhere to set the XG to act as a DHCP relay.
Ian
XGS118 - v21.5.0
XG115 converted to software licence v21.5.0
If a post solves your question please use the 'Verify Answer' button.
Could you elaborate on what you're trying to say? If the XG were my DHCP server, I wouldn't need it to relay anything. The relay is set in Network -> DHCP - Relay
Very simple, where does the XG relay function relay the request to without a DHCP server enabled in the XG?
Ian
XGS118 - v21.5.0
XG115 converted to software licence v21.5.0
If a post solves your question please use the 'Verify Answer' button.
Hello RyzenShine ,
Good day and thanks for reaching out to Sophos Community.
What you see on the firewall side is just normal (DHCP violation). https://support.sophos.com/support/s/article/KB-000039048?language=en_US alongside with it could you perform packet capture on end machines on VLAN 70 using Wireshark? and kindly check where on the Discover-Offer-Request-Ack of the DHCP process breaks on the end machine? https://wiki.wireshark.org/DHCP
Also could you do a TCP dump and drppkt on the firewall side while performing the request?
tcpdump -nei any host <dest IP> and port 67 or port 68
Console> drop-packet-capture host <dest IP> and port 67 or port 68
Many thanks for your time and patience and thank you for choosing Sophos
Raphael Alganes
Global Community Engineer, Support & Services
Are you a Sophos Partner? | Product Documentation | @SophosSupport | Sign up for SMS Alerts
If a post solves your question, please use the 'Verify Answer' button.
The award-winning home for Sophos Support videos! - Visit Sophos Techvids