networking network_error ai_generated true

DHCP: Address conflict detected for 192.168.1.100, disabling interface eth0

ID: networking/dhcp-address-conflict

Also available as: JSON · Markdown · 中文
85%Fix Rate
85%Confidence
1Evidence
2024-01-20First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
ISC DHCP client 4.4-4.5 active — — —
systemd-networkd 250-256 active — — —
dhcpcd 9.4-10.0 active — — —
Linux kernel 5.15-6.8 active — — —
Windows 10/11 DHCP client active — — —

Root Cause

The DHCP client received an ACK for an IP address, but then detected another host using the same IP via ARP probe, causing the client to release the address and disable the interface to avoid IP conflicts.

generic

中文

DHCP客户端收到IP地址的ACK后，通过ARP探测发现另一台主机正在使用相同IP，导致客户端释放该地址并禁用接口以避免IP冲突。

Official Documentation

https://www.isc.org/dhcp/

Workarounds

  1. 70% success Release and request a new IP: `dhclient -r eth0; dhclient eth0` to get a different address from the pool. 
    Release and request a new IP: `dhclient -r eth0; dhclient eth0` to get a different address from the pool.
  2. 85% success Identify the conflicting host by checking ARP table: `arp -a | grep 192.168.1.100` and remove it from the network, or exclude that IP from the DHCP pool on the server. 
    Identify the conflicting host by checking ARP table: `arp -a | grep 192.168.1.100` and remove it from the network, or exclude that IP from the DHCP pool on the server.
  3. 90% success Configure a DHCP reservation on the server for the client's MAC address to ensure it always gets the same IP and avoid conflicts. 
    Configure a DHCP reservation on the server for the client's MAC address to ensure it always gets the same IP and avoid conflicts.

中文步骤

  1. Release and request a new IP: `dhclient -r eth0; dhclient eth0` to get a different address from the pool.
  2. Identify the conflicting host by checking ARP table: `arp -a | grep 192.168.1.100` and remove it from the network, or exclude that IP from the DHCP pool on the server.
  3. Configure a DHCP reservation on the server for the client's MAC address to ensure it always gets the same IP and avoid conflicts.

Dead Ends

Common approaches that don't work:

  1. Setting a static IP on the client without checking the DHCP pool 80% fail

    The static IP may still conflict with the DHCP server's pool, leading to the same error or network instability.

  2. Restarting the DHCP client repeatedly (e.g., `dhclient -r && dhclient`) 85% fail

    The conflicting host is still on the network; the same IP may be reassigned, causing immediate conflict again.

  3. Ignoring the error and assuming it's a one-time glitch 95% fail

    The interface remains disabled, so the client has no network connectivity until manually re-enabled.