[IAG] DHCP cannot obtain the address after installation access
Problem Description
After the client computer installed the access plug-in, DHCP could not obtain the address. Manual release and re-acquisition (ipconfig /release and ipconfig /renew) still did not work.
Effective troubleshooting steps
- I captured packets on my computer and found that none of the DHCP messages were sent out, only unicast messages were sent, and broadcast messages were missing (normal address acquisition should be broadcast first and then unicast)
- Check the access policy and find that the customer has configured external connection control and external connection inspection policies. After removing the policies one by one, it is found that the problem can be restored after removing the external connection control policies.
- Check the policy configured by the client and find that the address of the DHCP server is included in the allowed list, but the IP address of the broadcast address is not added to the allowed list.
- After adding the broadcast address 255.255.255.255 to the allowed list of external connection control, the test can obtain the address normally
Root cause
The broadcast message is not released, resulting in the PC being unable to send packets normally.
solution
After adding the broadcast address to the allowed list, it can be obtained normally
Original Link
https://support.sangfor.com.cn/cases/list?product_id=22&type=1&category_id=8402&isOpen=true