0
votes
0answers
15 views

Strange network issue when moving EC2 elastic IP

Recently we had an issue with a Windows 2012 EC2 server, which meant that we had to move across to another instance. We duplicated the instance, ran some tests and moved over the elastic IP. Should ...
3
votes
0answers
67 views

VMXNET3 nic loses the ability to update ARP table after N hours

I have a fedora 18 VM that stops updating the arp table on eth1 after running for a number of hours to days. There are other VMs on the same hypervisor that can access all of the same networks without ...
1
vote
1answer
106 views

“Destination Host Unreachable” and ARP returns no addresses over LAN

I am currently trying to setup LAN over two machines with a network mask of 255.255.255.0 however I am receiving the following message when trying to communicate between them both; [root@alpha ~]# ...
1
vote
1answer
70 views

network level of veth doesn't respond to arp

I decided to play with veth : create a veth pair and send a ping from one end to another. $ ip link add type veth $ ip addr add 192.168.99.1 dev veth4 $ ip addr add 192.168.99.2 dev veth5 $ ip link ...
0
votes
1answer
55 views

what would happen when macchanger to gateway mac address? [closed]

I thought arpspoof GATEWAY_IP -t VICTIM_IP can be prevented by add a static arp entry on victim side, i.e. arp -s GATEWAY_IP GATEWAY_MAC I read ...
1
vote
1answer
196 views

Networking ARP table in windows cmd

I am reading the book practical packet analysis and I have just learned the fundamentals of the ARP protocol. They also added something about the arp -a cmd command. I'm curious about some of the ...
1
vote
2answers
191 views

Windows Domain controller ARPing for 169.254.0.0/16 addresses

I've been doing some sniffing on my company's network to try to clean up some of traffic and have noticed that one of our Server 2008 Domain Controllers is sending out ARP's every second or two to ...
1
vote
2answers
288 views

Physical switch not learning MAC address of virtual machines

I have a virtual environment running vSphere 5.1. I have two ESXis with a vDS between them. There is, for the purposes of the discussion, just one portgroup on that vDS configured to use a VLAN. The ...
2
votes
0answers
81 views

I am not able to connect to my server from my leased line internet connection

I am having some troubles connecting to my Fedora server from my static IP ISP connection. Usually I can ping that server with no problems. But other times it just gives me timeout responses. When ...
0
votes
0answers
60 views

Redhat 6.1 LVS (DR) over private subnet

I am trying to run LVS on RHEL 6.1, but with traffic from the routers to the real servers over a private subnet. with direct routing (behold this drawing: http://i.stack.imgur.com/aJ22w.png) ...
2
votes
0answers
108 views

Solaris 10 invalid ARP requests from 0.0.0.0? Link up/down every hour or 2

The guys at the data center where I'm hosting a server running Solaris 10 are telling me that my server is making a lot of invalid arp requests. This is an example of a portion of what was sent to me ...
1
vote
2answers
117 views

How to capture arp table when using network bridging?

I have a computer with 2 NICS that are bridged and I need a means of distinguishing between machines connected to eth0 from machines connected to eth1. I was hoping to use something like the "arp -a" ...
-5
votes
2answers
373 views

Can a computer route IP trafic between two LAN if it is not configured as gateway? [closed]

Having two LAN, each one have its own gateway, DHCP and internet connexion LAN 1 - IPs: 192.168.0.0-255, Mask: 255.255.254.0, Gateway: 192.168.0.1 LAN 2 - IPs: 192.168.1.1-255, Mask: 255.255.254.0, ...
-1
votes
1answer
114 views

How to discover devices other subnet [closed]

Printers like some thermal I have tried Bixolon and samsung laser printer ,even mikrotik router have a tool where they discover the device via its mac address.No matter what the ip is. And they ...
2
votes
2answers
310 views

Why do all computers on my network have the same MAC address?

I'm on a LAN provided by an ISP. My computer has its IP address, Subnet Mask, Default Gateway, DNS Servers(using DHCP). I just wanted to see the MAC addresses of all the computers on my LAN. After ...
0
votes
2answers
600 views

Multiple NICs with IPs from same network at Linux host respond to a single MAC

CentOS host is armed with multiple NICs. All NICs are bound to the same subnetwork (let it be 10.0.0.0/24). Their IP configuration is provided with DHCP server (as reservations). While trying to get ...
-1
votes
2answers
211 views

ARP Command doesn't display all devices

I have a machine on my network that needs to create a list of all mac addresses connected to the network. This is running OSX when I run the arp command it doesn't always display everything connected ...
4
votes
1answer
193 views

Cannot ping B from A until B pings A

I have a server cluster all connected on a local network(all physical machines, not virtual). When trying to ping from Server A to B, I get a Desitination Host Unreachable. I can ping from B to A no ...
1
vote
0answers
53 views

Can you SNMP poll the ARP table on Cisco ACE?

I'm trying to get a MAC <=> IP mapping from a Cisco ACE. Unfortunately according to this table, while it supports IP-MIB the ipNetToMediaTable and ipNetToPhysicalTable subtrees are not supported. ...
1
vote
2answers
191 views

Can a duplicate computer name be known before attempting to join the domain?

Techs in the field are deploying windows 7 pcs onto a domain. They complete one entry screen, which should give them a unique computer name. However, they are human and end up giving the pcs the ...
4
votes
3answers
913 views

Wireshark running on a server seeing lots of `ARP who has` with different tells

We're seeing some suspicious network activity, and when I was trying to see if it was one particular server of ours I ran a Wireshark trace. I noted a lot of ARP packets asking who has x.x.x.x, but ...
2
votes
1answer
156 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
votes
1answer
833 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 ...
0
votes
0answers
149 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 ...
2
votes
2answers
432 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 ...
4
votes
1answer
196 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 ...
12
votes
2answers
1k 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 ...
1
vote
2answers
284 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 ...
1
vote
1answer
55 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
votes
3answers
468 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
votes
2answers
373 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). ...
1
vote
0answers
170 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 ...
1
vote
1answer
281 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 ...
-1
votes
1answer
54 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 ...
1
vote
0answers
103 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 ...
1
vote
0answers
645 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. ...
6
votes
1answer
3k 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
votes
1answer
127 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 ...
0
votes
1answer
389 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 ...
6
votes
1answer
665 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 ...
8
votes
4answers
842 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 ...
4
votes
1answer
626 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 ...
0
votes
1answer
654 views

One To One NAT, only works on WAN?

We are attempting to test a One To One NAT configuration on a Cisco RV180 router, Cisco SMB support says that this setup below would not work. (they seem to be right) I know it has something to do ...
-1
votes
2answers
235 views

Activate Passive Arp learning

I want to enable my linux-kernel to passively listen (learn) the arp request broadcasted in the lan segment (arp request in the network not destined for me). Is there any configuration available?
2
votes
4answers
621 views

Extremely high arp fllooding from the router

My subnet is 10.162.0.0/16. We have a router with a couple of interfaces. Gateway for my subnet is 10.162.0.1. The router is situated in another building and I haven't direct access to it. Line from ...
0
votes
1answer
412 views

Router is continually broadcasting the same ARP request, with the exact contents

I hope the question is clear and that this is correct place to post the question. My router is broadcasting the same ARP frame over and over (once every second). It's probably not a big deal, but I ...
3
votes
2answers
4k views

Neighbour table overflow on Linux hosts related to bridging and ipv6

Note: I already have a workaround for this problem (as described below) so this is only a "want-to-know" question. I have a productive setup with around 50 hosts including blades running xen 4 and ...
2
votes
3answers
1k views

Strange linux neighbor cache entries (whole-world-is-link-local syndrome) (linux 3.0.0-16)

On absolutely standard ubuntu-server linux distro running only BIND cache, sometimes i see non-link-local ip addresses in the arp/nei table and there is no way to communicate with those entries After ...
1
vote
1answer
1k views

Linux: arp cache timeout for non existent hosts?

In Linux, is there a different arp cache timeout for non existent hosts? At my router, 192.168.0.1, i'm seeing aprox. 8 new entries every 10 seconds for an IP that has been down for a long time. ...
2
votes
1answer
287 views

Detecting network state with arping

I am developing system for detecting network actual state. One part is to get all IPs and their respective MAC addresses. Right now I am using arping in DAD (Duplicate Address Discovery) mode. I send ...