Address Resolution Protocol is a layer 2 networking protocol used for resolving layer 3 addresses (such as IP addresses) into layer 2 addresses (such as Ethernet MACs). It is used by network devices when communicating with devices on the same layer 2 network.
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Keepalived, Junos, and ARP caching
I'm trying to configure an active-passive stunnel setup, with the aid of Keepalived, for a public IP address at our company datacenter. I would like to know if a router or switch reconfiguration is ...
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0answers
26 views
Permanant ARP entries become Unresolved
We have a solution where a number of Solaris servers are in a private VLAN and no arp proxies exist in this VLAN, so to reach neighboring servers we must add static arp entries. Each other server in ...
2
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1answer
60 views
ARP/Mac address table
What is the difference between a mac address table and an arp table? Is it correct to say only one arp cache is kept for each switch which self learns to forward information to another host, and every ...
2
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1answer
64 views
Linux machine does not answer an ARP request
We have this situation: A router, which is an Ubuntu VM, has multiple VLAN interfaces on the same physical NIC. Those VLAN interfaces are dynamically configured and torn down and attached to networks ...
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0answers
50 views
Broadcom NetXtreme II GigE Teaming Does Not Use Unique MAC, Causing Collisions
I currently have a new Dell server on my local (inside) network that I have setup to use three of the four nics to create a team. Examples below.
NIC_1 - mac: 000000000001 - ip: n/a
NIC_2 - mac: ...
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1answer
43 views
How to decrease linux box arp response?
I had known that I can not stop arp flood from others, so I wonder to know how can I decrease the response times per second, so that my cpu wont cost too much for arp flood, any tips?
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45 views
Can't reproduce arp non-response issue with spoofed packets
I'm trying to debug an issue involving a KVM virtual machine instance where the instance doesn't respond to network requests when the source is on another physical machine, which is on the same subnet ...
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2answers
79 views
arp packet received larger than packet sent, why?
I'm trying to debug a networking issue. During this process, I've noticed that when I try to do an arping, the received arp packets are larger than sent arp packets, as outputted by tcpdump.
(Note ...
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1answer
60 views
tcpdump on interface when pinging nonexistent hosts on local network
I've statically configured the IP address of an interface on a server:
ip addr add 10.40.0.6/16 broadcast 10.40.255.255 dev eth1
If I try to ping a machine on the network (e.g., 10.40.0.1), it ...
11
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1answer
485 views
arp-requests cannot be seen by specific nodes
I create an open ad-hoc wlan by using iwconfig (I have the same issue with wpa_supplicant as well). there are 4 nodes on the network as seen on the figure below. The nodes run ubuntu 12.04 and debian ...
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2answers
138 views
Protection from ARP spoofing
I'm running Linux and I know my gateway will always be 192.168.1.254 with MAC address aa:aa:aa:aa:aa:aa.
Is there any way I can instruct my machine to only ever use this MAC address for the gateway ...
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0answers
95 views
arp reply is not processed
My eth0 interface does not process a legitimate arp reply.
When I try to ping a host, I see arp request and reply with tcpdump from the host I try to ping from, but ip neigh says that there is a ...
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1answer
43 views
Can arping by IP but not MAC address
I have an interface that I can arping to by its IP, but not its MAC address:
# arping -i eth2 10.10.0.153
ARPING 10.10.0.153
60 bytes from 02:68:b3:29:da:98 (10.10.0.153): index=0 time=81.062 usec
60 ...
2
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3answers
129 views
arp who-has requests view vlan isolated different addresses (single NIC)
I have debian hosts which are connected through trunk port on 5 different vlans. But this host respond to arp "who-has" requests of all of their differents ip. I wish understand why ...
Here the ...
3
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2answers
174 views
Windows 7 Requires ARP for UDP?
Seems like my Windows 7 box (with 2 NICs if that's relevant) requires an ARP response before it sends packets to a certain IP address. The specific context I'm in is running a TFTP server (TFTPD32). ...
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0answers
69 views
Cannot ping any machine on local network (embedded linux device)
I have an embedded linux installation (custom built using buildroot, uClibc and busybox) and I am unable to ping any machine on my local network. My /etc/network/interfaces file is as follows
auto lo
...
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1answer
132 views
Multiple VLANs - how Linux / Debian process packets
I can't find answer about how linux processes incoming packets from different VLANs, that do not belong to a subnet assigned to a VLAN.
Imagine this situation. On Linux machine with the following ...
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1answer
79 views
Pinging between hosts through Layer2 tunnel fails
I have some serious problems with my newly setup network with a Layer 2 VPN tunnel.
I draw a little diagram to show the simple version of the setup:
The green lines are through the VPN, the blue ...
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1answer
116 views
Cisco ARP table: determine directly connected devices
I have a Cisco switch and a big list of servers on the network. I need to determine what servers are connected directly to that switch. Will searching for the MAC address of each server in the ...
2
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1answer
95 views
arp --detete is not deleting an entry; merely marks entry as “incomplete”
I run arp --delete and it leaves the entry but it's simply marked as incomplete. I expected --delete to entirely remove the entry.
Does anyone understand what is occurring here?
$ sudo arp -avn
? ...
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0answers
110 views
openvpn connects but does not work until server pings client
I'm trying to configure a connection using openvpn from a windows 7 client machine to a linux host. I'm using openvpn in the traditional routed mode using tap devices, and the configuration I'm using ...
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1answer
117 views
Switch CAM table and ARP messages
When the switch CAM table is empty and it receives an ARP message, does it add to the CAM table the source MAC address ?
In Packet Tracer I saw that it does add it, but I read in some book that the ...
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0answers
36 views
modem arp cache raining on my parade
I have a cable business account with my local provider who uses arp cache in the modem for ip addressing both dynamic and static. with my old dsl I did not have this issue but with Shaw I do.
I'm ...
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1answer
46 views
What network traffic when ethernet plugged in [closed]
So in a general sense (e.g. not windows, linux specific) what network traffic is generated when I first boot up/plug in a network cable.
Basically:
Detect DHCP server
Pull an IP Address from DHCP
...
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1answer
51 views
ARP request effect on destination's ARP tables [closed]
I'm trying to figure out how do ARP tables exactly work. If I send a ping from host A to host B, host B is obviously added to the ARP table of host A. However, host A is also added to the table of ...
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84 views
stop arp poisoning on a 5448 powerconnect switch
We have to disable arp poisoning on our dell 5448 switch. Right now it has all our production machines running on it and I'm not a networking guy at all so I don't want to run a command that will ...
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0answers
186 views
Dynamic ARP Entries turning into Static ARP entries
I recently acquired a client that has a strange ARP caching issue on one of thier servers.
I have a server that will eventually start turning it's dynamic ARP entries into static ARP entries. This ...
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1answer
97 views
Why host and vmware guests fail to get MAC of each other? [closed]
I have Windows 7 64bit host running VmWare Workstation 8 with two CentOS 6.3 guests. All guests adaptors are bridged with statically assigned ip's. Connectivity bitween host and guests was fine for ...
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0answers
61 views
What is the meaning of the QUEUE in arptables
I use the nfqueue target of iptables in order to get packet to the nfqueue and do some business rules on them.
iptables -A INPUT -p tcp -j NFQUEUE --queue-num 0
I need to do the same on arp reply ...
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0answers
347 views
Arp request is not resolved
On my machine, I have assigned ip addresses for two interfaces which are connected through a cable. They are connected with 10G ports.
When i tried to ping the two addresses, ping was not working. ...
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0answers
54 views
Server Core DNS Server in VSphere doesn't respond to ping and needs continuous arp clean
I have a VSphere installation hosting two Windows Server 2008 R2 installations. One of them is a complete install that serves as a DHCP server and that I use for administration. The other install is a ...
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1answer
854 views
How do I poll the ARP table with an SNMP OID?
When you need to poll the ARP table of a device, conventional wisdom is to use ipNetToMediaPhysAddress or atPhysAddress; however, both of these OIDs are deprecated according to Cisco's documentation.
...
5
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1answer
93 views
Sender Information Not Cached on the Receiver During an ARP Request
I'm currently trying to get my head around more advanced networking concepts. The way I am doing this is by going on one of the servers I look after as a sysadmin and running network captures to see ...
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1answer
151 views
arp across subnets which devices can be detected?
i have some devices connected in the same physical network (LAN) but in different subnets. I want to detect them all with the ARP from my computer. My Computer is also in the same physical network but ...
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1answer
151 views
Update mysql database with arpwatch textfile database
I'm looking to keep arpwatch entries in a mysql database to crossreference with other information I'm storing based on mac addresses. I've manually imported the arpwatch database into my mysql ...
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1answer
339 views
Random and Selective ARP blindness in VMWare ESXi 4.1
We have multiple VMWare ESX servers spread out amongst our company, doing various tasks. One particular ESXi host is exhibiting very peculiar behavior. We detect it when our monitoring system ...
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2answers
110 views
Host spreads wrong MAC Adress of router on the WIFI [closed]
Strange things are going on our network.
Since yesterday a host which is actually not on our subnet spreads wrong ARP Replys on our network. To be precise, only on the WIFI. If I connect my Laptop to ...
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1answer
394 views
Windows server sending constant ARP requests to offline devices
We have a Windows 2003r2 server which is sending intermittent ARP requests to several devices which are no longer on the network. The result of this is disruption to a PLC which is running over ...
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4answers
523 views
Network throughput issue (ARP-related)
The small college where I work is having some very strange network issues. I'm looking for any advice or ideas here. We were fine over the summer, but the trouble began few days after students ...
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1answer
203 views
Solaris Slow ARP Failure Unreachable Host
We have been experiencing slow timeouts for unreachable hosts is extremely slow. Recent testing in our lab shows it may be a delay reporting negative ARP lookups. Dumping traffic during attempts to ...
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2answers
129 views
Find IP address from a MAC address
Is there anyway to find the IP address of a MAC address using a command? I was thinking something like arping might work but can't seem to find much information on it.
2
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1answer
543 views
Failure to obtain IP with ARP over Wi-Fi with personal Wi-Fi router in client mode
I'm trying to connect a Samsung TV to the Internet using a TL-MR3020 personal wireless router in client mode. The TV fails to connect to the network. It sees the ethernet cable connected though.
...
4
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1answer
450 views
Arp requests with odd source IP go unanswered
I'm having a server with network connectivity issues that I presume come from issues with arp protocol handling.
Let's say the network topology is as follows:
network 192.168.106.0, netmask ...
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1answer
135 views
Proxy arp and 1:1 NAT
I have a Linux router with 2 NICs doing masquerade from network 192.168.0.0/24 to an ADSL router.
users <----> NIC A [router] NIC B <----> INTERNET
Now I'm experimenting with proxy arp ...
0
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1answer
857 views
arp -n responds with (incomplete) on the wrong subnet, can't remove it
context
There are 2 servers:
server1 - eth0 10.129.76.16
eth0.2 192.168.0.103
server2 - eth0 10.129.79.1
eth0.2 192.168.62.101
The 192.x.x.x addresses are connected to the ...
2
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1answer
273 views
pfSense can't talk ARP beyond a switch two hops away
I have the following devices on vlan93 on my network:
pfsense (192.168.93.1)
core-sw1 (192.168.93.2)
edge-sw1 (192.168.93.3)
pf-switch (192.168.93.100)
devices (192.168.93.120)
Physical ...
6
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5answers
2k views
Cluster failover and strange gratuitous arp behavior
I am experiencing a strange Windows 2008R2 cluster related issue that is bothering me. I feel that I have come close as to what the issue is, but still don't fully understand what is happening.
I ...
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0answers
207 views
virtualbox bridged adaptor works only guest->host but not host->guest
I have virtualbox 4.1 on a ubuntu 12.04 host. On my host I have a virtual interface eth0:1 configurend as 10.0.1.1. I have a few virtual machines using bridged adapters, configured in the 10.0.1.0 net ...
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2answers
497 views
Routing to other subnets results in wrong ARP requests
I would like to manually set up routing to subnet 95.168.0.0/16 through IP which is an alias: 94.23.94.161. IP alias is set up like that:
/sbin/ifconfig eth0:0 94.23.94.161 netmask 255.255.255.255 ...
2
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1answer
1k views
Why ARP request is unicast?
I have a wireshark capture here that indicating a unicast ARP request from source to destination. As per my understanding ARP requests (including gratutious ARP) use broadcast.
In what case the ...
