Tagged Questions
2
votes
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 ...
1
vote
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?
0
votes
0answers
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 ...
2
votes
2answers
81 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
61 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
votes
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 ...
1
vote
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 ...
1
vote
0answers
97 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 ...
2
votes
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 ...
1
vote
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
...
0
votes
1answer
133 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 ...
2
votes
1answer
96 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
? ...
0
votes
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 ...
1
vote
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 ...
4
votes
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 ...
1
vote
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 ...
1
vote
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 ...
-1
votes
2answers
169 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
2answers
2k 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 ...
0
votes
1answer
588 views
Why is a ping response being sent to the wrong gateway?
In a previous question, I was trying to determine why my OpenVPN clients could not ping the server LAN, even though the server LAN could ping the clients.
Having investigated this further, I ...
2
votes
1answer
1k views
Ubuntu Linux - two interfaces, same subnet, different vlan - MAC/ARP issues
I'm attempting to setup a server that needs to have interfaces on the same IP subnet, but different VLANs:
eth1.102 Link encap:Ethernet HWaddr 00:50:56:b1:00:0f
inet addr:10.1.1.6 ...
2
votes
2answers
1k views
2 NICs 2 IPS same subnet
I am setting up a SUSE 11 box that has two NICs:
eth0 - 192.168.10.150/24 - 00.0C.29.DC.10.CA (MAC)
eth1 - 192.168.10.151/24 - 00.0C.29.DC.10.DE (MAC)
I need both in the same subnet since they will ...
2
votes
3answers
663 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
192 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 ...
0
votes
1answer
1k views
Linux storing arp cache entries using wrong interface
I'm trying to get two virtual machines (running CentOS) to talk to host (Ubuntu 10.04) using VDE and the outside network.
So far I'm running into an ARP issue.
On Host I have a physical eth0 and a ...
5
votes
2answers
678 views
linux routing bug?
I have been struggling with this not easily reproducible issue since a while. I am using linux kernel v3.1.0, and sometimes routing to a few IP addresses does not work.
What seems to happen is that ...
1
vote
1answer
364 views
arp requests are sent continuously and my linux machine disconnected to the world [closed]
I have the following problem and really need your help
I'm implementing a small server to receive request from client on port 18999(just sample) using TCP socket.
When I tested my server by using a ...
5
votes
1answer
264 views
Which NIC have the IP address?
If I have two NICs where I know the MAC addresses.
Without logging into the server, how do I figure out which have the IP address 10.10.10.10?
Can arp somehow be used for this?
2
votes
1answer
191 views
Multi-NIC Linux machine's NICs are responding to each other's ARPs regardless of arp_filter setting
I have an old Linux machine running a 2.4.37 kernel. In the machine are two NIC cards both on the same network with different IPs. For some testing, we want each IP's traffic routed through that NIC, ...
3
votes
1answer
1k views
How to test 10 gigabit Intel X520 on Ubuntu
I got Intel X520 and connected it to PCI-E x16. The card is recognized as 10 Gbit by ethtool:
# ethtool eth5
Settings for eth5:
Supported ports: [ FIBRE ]
Supported link modes: ...
0
votes
2answers
1k views
Linux is not sending arp request
We have a local network that is connected to internet through linux gateway. There are about 50 workstations in LAN. We recently started observing a problem that gateway sporadically stops responding ...
9
votes
5answers
5k views
ARP replies contain wrong MAC address
I've got a robot running linux with wired and wireless adapters. When I boot up, it connects to the wireless fine. When I assign an IP to the wired (either statically or with DHCP), it looks like it ...
2
votes
2answers
3k views
2
votes
2answers
2k views
Is it possible to use proxy-arp back to the same interface?
I have a WiFi Access Point connected to a Linux Router. The Router is itself connected to the Internet. For multiple reasons (mostly to control security and quality of service), I want to force all ...
2
votes
2answers
4k views
Linux bridge responding to arp on wrong interface?
I'm trying to build a silent bridge for monitoring purpose. My computer is running linux 2.6, brctl 1.4 and has 3 NIC:
eth0, with an assigned IP, used for SSH maintenance
eth1, and eth2 , the 2 ...
1
vote
2answers
290 views
Is there a way to trace what's sending gratuitous arps?
We have a box that's just started acting up and we're not really sure why. It has IP address (dummy examples) 199.199.199.1 on eth0, 127.0.0.2 on eth1, and 199.199.199.2 on eth1:0.
Recently, for some ...
0
votes
1answer
536 views
Two NIC's in the same ip segment
What is the best technical solution to solve this?
I have a /24-segment with two NIC's in one Linux Server
(lets call it srv) that have two IP-addresses in this segment.
NIC1 / eth0 / 10.10.1.101 / ...
8
votes
3answers
6k views
How to broadcast ARP update to all neighbors in Linux?
Some clients in the subnet has cached the IP with old MAC address, I want them to update the new value by doing a ARP broadcast, is it possible in Linux?
1
vote
1answer
208 views
How to prevent response to who-has requests on virtual eth interface?
we use small embedded X86 linux servers equipped with a single physical ethernet port as a gateway for an IP video surveillance application. Each downstream IP cam is mapped to a separate virtual IP ...
12
votes
2answers
3k views
Strange: why does linux respond to ping with ARP request after last ping reply?
I (and a colleague) have just noticed, and tested, that when a Linux machine is pinged, after the last ping it initiates a unicast ARP request to the machine that initiated the ICMP ping. When pinging ...
0
votes
6answers
1k views
Network routing issues on Linux
I was hoping someone out there would be able to look at this and let me know what I have missed. I have 4 machines and for some reason, only 1 of them can talk to the other 3 via their private IP ...
3
votes
3answers
12k views
How can I fix a bad arp entry?
I'm just guessing that arp is my problem...
I have a linux drbd server cluster set up, and due to some power issues had to unplug the switch that connects the two servers. As a result, both servers ...
12
votes
5answers
20k views
Ubuntu Linux - multiple NICs, same LAN… ARP responses always go out a single NIC
We've got AT&T U-Verse internet service, which has an extremely boneheaded DSL gateway.
We have 5 IPs (netmask 248), but the gateway is incapable of doing anything other than a single IP -> ...
