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ARP responding with incorrect address
Hi all,
I am experiencing some network issues that I believe are a result my linux PC responding to ARP requests with incorrect address information. The PC is running openSuSE 10.3/kernel 2.6.22 and has two RTL-8139 based network cards. ifconfig is:
eth0 Link encap:Ethernet HWaddr 00:00:E8:6D:74:28
inet addr:192.168.1.4 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:501 errors:0 dropped:0 overruns:0 frame:0
TX packets:175 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:66843 (65.2 Kb) TX bytes:33450 (32.6 Kb)
Interrupt:16 Base address:0xc000
eth1 Link encap:Ethernet HWaddr 00:50:BA:8B:FE:56
inet addr:192.168.1.10 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:510 errors:0 dropped:0 overruns:0 frame:0
TX packets:5 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:69732 (68.0 Kb) TX bytes:372 (372.0 b)
Interrupt:17 Base address:0xe000
As can be noted eth0 = 192.168.1.4 and eth1 = 192.168.1.10 but the PC always responds to ARP requests with the eth0 MAC address regardless of which IP is being queried. A packet capture of ARP traffic from another PC is below:
Packet 1 - ARP Request - 192.168.1.11 -> 192.168.1.4
Packet Info
Flags: 0x00
Status: 0x01
Packet Length: 64
Timestamp: 16:04:34.052976700 01/25/2008
Ethernet Header
Destination: FF:FF:FF:FF:FF:FF
Source: 00:19:21:7C:E6:3F
Protocol Type: 0x0806 IP ARP
ARP - Address Resolution Protocol
Hardware: 1 Ethernet
Protocol: 0x0800 IP
Hardware Addr Length: 6
Protocol Addr Length: 4
Operation: 1 ARP Request
Sender Hardware Addr: 00:19:21:7C:E6:3F
Sender Internet Addr: 192.168.1.11
Target Hardware Addr: 00:00:00:00:00:00
Target Internet Addr: 192.168.1.4
Packet 2 - ARP Repsonse - 192.168.1.4 -> 192.168.1.11
Packet Info
Flags: 0x00
Status: 0x01
Packet Length: 64
Timestamp: 16:04:34.053972700 01/25/2008
Ethernet Header
Destination: 00:19:21:7C:E6:3F
Source: 00:00:E8:6D:74:28
Protocol Type: 0x0806 IP ARP
ARP - Address Resolution Protocol
Hardware: 1 Ethernet
Protocol: 0x0800 IP
Hardware Addr Length: 6
Protocol Addr Length: 4
Operation: 2 ARP Response
Sender Hardware Addr: 00:00:E8:6D:74:28
Sender Internet Addr: 192.168.1.4
Target Hardware Addr: 00:19:21:7C:E6:3F
Target Internet Addr: 192.168.1.11
Packet 3 - ARP Request - 192.168.1.11 -> 192.168.1.10
Packet Info
Flags: 0x00
Status: 0x01
Packet Length: 64
Timestamp: 16:04:39.994980700 01/25/2008
Ethernet Header
Destination: FF:FF:FF:FF:FF:FF
Source: 00:19:21:7C:E6:3F
Protocol Type: 0x0806 IP ARP
ARP - Address Resolution Protocol
Hardware: 1 Ethernet
Protocol: 0x0800 IP
Hardware Addr Length: 6
Protocol Addr Length: 4
Operation: 1 ARP Request
Sender Hardware Addr: 00:19:21:7C:E6:3F
Sender Internet Addr: 192.168.1.11
Target Hardware Addr: 00:00:00:00:00:00
Target Internet Addr: 192.168.1.10
Packet 4 - ARP Response 192.168.1.10 -> 192.168.1.11
Packet Info
Flags: 0x00
Status: 0x01
Packet Length: 64
Timestamp: 16:04:39.995969700 01/25/2008
Ethernet Header
Destination: 00:19:21:7C:E6:3F
Source: 00:00:E8:6D:74:28
Protocol Type: 0x0806 IP ARP
ARP - Address Resolution Protocol
Hardware: 1 Ethernet
Protocol: 0x0800 IP
Hardware Addr Length: 6
Protocol Addr Length: 4
Operation: 2 ARP Response
Sender Hardware Addr: 00:00:E8:6D:74:28
Sender Internet Addr: 192.168.1.10
Target Hardware Addr: 00:19:21:7C:E6:3F
Target Internet Addr: 192.168.1.11
Packets 1 and 2 are the ARP request and response for the eth0 address and they appear to be correct. Packets 3 and 4 are the ARP request and response for the eth1 address and as can be seen in packet 4, the ARP response lists an IP address of 192.168.1.10 (eth1) but the MAC address is actually from eth0 (192.168.1.4). I have read about the ARP-flux issue and while it does not seem exactly the issue I am seeing I tried the recommended arp-filter solution but it did not seem to fix the problem. The 192.168.1.10 ARP responses continue to come back with the incorrect MAC address.
Is this a known issue? Are there other solutions that I could try? Any insights or recommendations would be greatly appreciated.
Thanks
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before someone splits the answers by responding here.
