Arp Entry Does Not Exist

Command Manual - ARP H3C S9500 Series Routing Switches Chapter 1 ARP Configuration Commands 1-1 Chapter 1 ARP Configuration Commands 1. Unable to copy file during install/uninstall. 40VS, R76, R77. – If an ARP entry does not exist, the switch sends an ARP query and tries to resolve the IP address. This blog will cover techniques on how to identify and resolve Office installation failures. I'm trying to create a service to a memcached service sitting on one of our servers by following this documentation:. You do not usually need this command, because nmcli can handle polkit actions related to NetworkManager operations (when run with --ask). Error: The setup. pid) does not exist, No such process. When is an entry removed from an ARP cache? An entry in an ARP cache is removed after a pre-determined timeout period (e. This seems mostly useless in home networks, so you can save about 5 seconds on every connect by adding the following line to /etc/dhcpcd. Use the show ip route command to determine whether a routing table entry exists for the target network. It is suggested that instead of deleting an address, the Receipt From values under the address simply be deleted. If the ACL does not exist, it is created first. application, Culture=neutral, PublicKeyToken=0f612f649c4a10af, processorArchitecture=msil. Solaris 10 ARP problem. When you add a new entry, if the entry IP address does not exist in the ARP table, the entry will be added to the table. Entry names do not have macrons or breves. The following list details several methods to determine which types of traffic are being processed by the Cisco NX-OS device CPU:. /T Creates directory structure, but does not copy files. 178 does not exist at all. If you do not use the entry size, the result may not be valid. IP address is considered unavailable if either address or interface address is assigned to is invalid or does not exist. For example, a Leaf member of VTEP 1 has an ARP entry for its locally connected host, and an ARP entry for the remote host learned via VXLAN:. The host does not exist to respond to the ARP query. There is no way it could be added by my software, such functionality just does not exist. The argument if_id is the Interface Identification number for which to check the ARP table. 940 941 resend_igmp 942 943 Specifies the number of IGMP membership reports to be issued after 944 a failover event. The IP addresses must be in the same subnet. network-plus news group. Reverse Address Resolution Protocol (RARP) If only the MAC address of a host is available, the host can send and receive RARP messages to obtain its IP address. register: Used to register variables defined in a module when it is invoked in a task The registered data is stored in JSON format The value of the variables set using the register clause is always a dictionary, but the specific keys of the dictionary are different, depending on the module that was invoked. NSX-T Tile does not work with Pivotal Application Service (PAS) Isolation Segments which deploy their own GoRouters and TCP Routers. certification. Only one port can be added every time the command is executed. It works on some machines that do not follow the WoL standard exactly. The lack of responses (and the lack of documentation on this question) makes me think that ARP caches are not a profile component. Wireshark shows an ARP attempt to resolve the address but as its not there the. ATF_USETRAILERS is obsolete and should not be used. The IP addresses must be in the same subnet. It's when I add a second statement for an additional "if exist" (either 2010 or 2013) that nothing happens. When the traffic is received by IX Switch, as the destination mac-address does not exist in CAM table, the switch will flood the frame to all ports (except receiving port) out. 40VS, R76, R77. If the display of the message was initiated because a system table does not include an entry which it was expected to contain, the short text should not contain a reference to the table but at most a note on the entry: Good: E: Order type & is not valid (Please check entry). For example, a host can not only update an existing ARP table entry, it could create an ARP table entry if one does not exist. If IP finds that a host entry exists and matches the destination IP address, it will forward the packet to the next hop associated with that host entry. * Activation of C:\application_path\application_name. Enable to apply Location conversion to the reply’s HTTP header only if the host name portion of Location matches the request’s Host field or, if the Host field does not exist, the host name portion of the request’s URI. Extra trivia on file downloading:. The hardware-switching CEF table cannot forward this packet because it does not have rewrite information. From time to time I can observe the following behaviour (random machine, random zone). If an entry does not exist, the function forces the Network Core to resolve and cache the IP address into the internal ARP table buffer. The ARP command only works once. Below is a summary of the errors, details of these errors are listed later in the log. Pharming N. By continuing to use this site, you are consenting to our use of cookies. Else, if the entry IP address already exists in the ARP table, the entry will be updated. With TCP/IP networking, a data packet must contain both a destination MAC address and a destination IP address. Ensuring the install-state of setup controller files for all Products. If the server does not send an ARP Request packet to Switch Module A, Switch Module A still maintains the ARP entry on Port2. ==to: The display may not reflect information for certain devices which support ARP offload. steelscript. Software ARP entry and session creation: When ISG receives the first packet, ISG will first try to create a software session. Host entries are usually found in routing tables when ICMP (Internet Control Message Protocol) has added the entry because of the pathMTU algorithm, or from an "ICMP redirect" call. If the ATF_NETMASK flag is set, then arp_netmask should be valid. en-us\setup. If I were using name resolution for MAC addresses, ethers makes more sense to use. Ethernet LAN Attacks 1. I see the ARP requests, but > the server does not respond to it. I did find a way to disable gratouitous ARP (which for windows appears broken) using this registry entry. The ARP command only works once. /proc interfaces ARP supports a range of /proc interfaces to configure parameters on a global or per-interface basis. The IP address or hostname entry for the client does not exist in /etc/inet/hosts. This is often caused by Network Load Balanced Servers without a corresponding switch configuration. I'm trying to create a service to a memcached service sitting on one of our servers by following this documentation:. Remove a tag from the entry. The action that a switch will take when it does not have a map for the source MAC address is to enter it into the MAC address table (the switch will actually update this even if it does have an entry). ARP Spoofed packets [split posts] is it not, because the only ARP requests are being made to/from my machine to the router as well as to/from the other clients. If an ARP entry does not exist, the switch sends an ARP query and tries to resolve the IP address. Also, keep in mind that if you delete a last entry in the. - If an ARP entry does not exist, the Layer 2 traceroute utility sends an ARP query and tries to resolve the IP address. I configured everything in Polycom based on the below document however, Device is still showing "none none" in communication manager. After 5 ARP requests without any reply, a Destination Host Unreachable ICMP packet will be generated by your router. Hello Team, I have Polycom IP 5000 which I am trying to register on CUCM version 11. Steven Davidson Mar 8, 2014 3:08 PM ( in response to Arjun ) If you're pretty sure of the switch (you say 90%) but don't know the exact port then what I would do is issue the 'show mac address-table interface' command on each up/up port on that switch until you find one that doesn't have any mac. The 939 layer2+3 value was added for bonding version 3. It may or may not get a source port, or TCP connection since all we know is that _something_ on the server is trying to contact that IP. I therefore disconnect from the wireless network, and my wireless-interface default router goes away. 0 to the network processor. This is nothing but ARP Poisoning. Join GitHub today. Instead of retrieving all aliases and resolving the alias reference, first retrieve the entire list of aliases (1 query) and then correlate to resolved alias references. ctl file does not exist, you may create the file. ARP poisoning - an attack that misleads computers or switches about the actual MAC (physical address assigned to the NIC [network interface card) address of a system; uses and ARP request and an ARP reply P. • MGate could not drop unnecessary RTU bytes. Even when we shut the PC in question down, the address remains in the arp table. ARP Vulnerabilities Vulnerabilities are said to exist in ARP, when any system can spoof a reply to an ARP request and the system that will cache the reply would overwrite the existing entry and add the entry if one does not exist. Do what I said and cd /tftpboot and run rm *. Please do not allow staff, students or other personnel who do not have key card access into the facilities. A non-global zone loses contact with the outside world, ie. Enable IP Source Guard in interface 1/0/2. If the /etc/tftpaccess. 2 does not support proxy network ARP entries, so this should be set to 0xffffffff, or 0 to remove an existing proxy arp entry. Command Manual – ARP H3C S9500 Series Routing Switches Chapter 1 ARP Configuration Commands 1-1 Chapter 1 ARP Configuration Commands 1. d/ipmi start (requires the OpenIPMI package. Because of this there is no entry in the ARP table of the Cisco switch it is connected to. /24 network: This time R1 receives the ARP request and responds to HostA. rarpd daemon is not running on the server. The Hyper-V Switch will intercept this request and send it to the Host Agent. What is ARP? 4. The software does not respond to any ARP requests. 1 either, that IP has not been assigned to anyone or anything, and is not being handed out by DHCP. When is an entry removed from an ARP cache? An entry in an ARP cache is removed after a pre-determined timeout period (e. If the entry does not exist in the ARP cache, all tested OS's allow the creation of a new entry by an ARP request message. In this case, packets sent from Switch Module A to the server are still forwarded through Port2 until the ARP entry is aged out. When the traffic is received by IX Switch, as the destination mac-address does not exist in CAM table, the switch will flood the frame to all ports (except receiving port) out. This IP address that pops up, 192. • Any system can "spoof" (impersonate) an ARP reply to an ARP request • Receiving system will cache the reply - Overwrite existing entry - Adds entry if one does not exist • Usually called ARP "poisoning" • Network administrators should monitor IP and MAC address mappings to check for anomalies Some Types of Attacks to. Re: IP arp displaying mac but not in CAM table. Some hosts require an explicit update to the arp table to add new entries: # arp -s ether portland 080011010045 # arp -s ether corvallis 080011010046 The ether switch indicates an ethernet address. Support for proxy arp entries for networks (netmask not equal 0xffffffff) was dropped in Linux 2. Previously only static route employed. + Cannot delete a subkey tree because the subkey does not exist. Auxiliary Function The auxiliary function for ZXR10 devices is as follows. Enable to apply Location conversion to the reply’s HTTP header only if the host name portion of Location matches the request’s Host field or, if the Host field does not exist, the host name portion of the request’s URI. It is not clear that these are in use, though if so their assignment does conflict with those above. 40VS, R76, R77. " This is because the incomplete ARP indication (all-zeros MAC address) does not work the same way a completed ARP cache entry does. Raw profiler data is generated in the raw profiler data table with an unique trace_id. When you start to type [[, if the page exists, you'll be able to select it from the list. a required route table entry does not exist to reach the IP address (request unsuccessful) a required ARP entry does not exist and ARP request timed out (request unsuccessful) a valid reply is received (request successful). I CANNOT ping it from Laptop A. The ARP entry addition failed: Access is denied. With this ability, the server can answer requests even if it does not have the information. ARP Vulnerabilities. Rui Ueyama It's true that arp table entries have limited lifetime, and there's a chance that you miss an arp table entry because either (1) it's expired or (2) does not exist from the beginning. If I were using name resolution for MAC addresses, ethers makes more sense to use. If you want the host to get an IP from the DHCP server then whichever vlan the host is in you need to go to the switch that routes for that vlan and on the L3 SVI you need to add an ip helper-address ie. You can not send data to a IP that does not exist. I had no clue why this was happening and, in blind attempt to reproduce the issue, I wrote a script to delete ARP entry then add it again after some seconds. HotFix 210-1003942 - Reports do not print if MS SQL database contains more than 15 characters; HotFix 210-1004962 - Incorrect serial cost assigned to Order Entry Shipment for items using Serial Costing Method; February. arp ARP address family, handling packets vi bridge. (Which is the condition here as there does not exist any TCP connection between hosts 192. I used the keywork interface (set security Nat proxy-ARP interface ge-0/0/0. I configured everything in Polycom based on the below document however, Device is still showing "none none" in communication manager. 28'31 Seven patients were found to have. All NAT pools (for static and dynamic NAT in NAT rules, outbound load balancing, or server pool load sharing) for which the generation of Proxy ARP entry is set (addresses belonging to a NAT address pool that are not used as host addresses by other IP hosts). From time to time I can observe the following behaviour (random machine, random zone). application resulted in exception. In which case, you will not need to use the ARP command. start_date. Even ARP didn’t work at all. If the ATF_NETMASK flag is set, then arp_netmask should be valid. The Remove ARP Table Entry (QtocRmvARPTblE) API removes one or all dynamic entries from the ARP (Address Resolution Protocol) table for the specified line. The router must have a static ARP entry binding the Virtual-IP to the desired Multicast MAC address. out of just 90 packets captured about 80% are ARP request for this non existent server. It seems like a lot. The neigh/* sysctls did not exist before Linux 2. ARP response and no entry in the ARP table. You could probably put in a static ARP entry for the non-existent printer, and then use wireshark to sniff out the source of the packets since the router would then be able to forward the packets. Script is run by a scheduler entry, will reoccur each day and log an entry if the process fails. Traffic capture (tcpdump) on the Check Point Security Gateway shows that it answers all ARP Requests with its MAC Address - either on a specific interface, or on all interfaces. Click DisableTaskOffload. If an event is due, the variable waittime is set to NU_NO_SUSPEND. Recovery Restart the NonStop TCP/IPv6 subsystem in the processor in which the event occurred and send the online processor dump file to your service provider for analysis. Destination does not respond: ping displays No Answer message. If it does not exist, then ovs-vswitchd will attempt to obtain the CA certificate from the SSL peer on its first SSL connection and save it to the named PEM file. Quite simply, most organizations are not prepared for this style of threat. If the MAC address is all zeros, the ARX could not find the IP address through ARP; likely the IP address does not exist in this case. If I trace the AppServer, I see that it reads tnsnames. 99) default:0). The OS that are vulnerable to ARP Spoofing are as follows Windows 95/98/2000 ?. I have deployed it successfully if my batch only has one "if exist" uninstall command. If the matching source prefix does not exist, the IP–MAC address pair is rejected. That method tends to work more often. Remove a tag from the entry. HotFix 210-1003800 - Printer options are not saved if print to printer from Preview – Install Sage 300 ERP 2012 PU1 First. Here is a link to the script. In most LAN environments this does not pose any problems because all devices will respond to a ping request. Previously only static route employed. Do not describe the history command if this entry does not exist. Rather, NuttX supports only what are referred to as POSIX real-time signals. Tunnel does not exist if there is no output of the commands below:. Instead of retrieving all aliases and resolving the alias reference, first retrieve the entire list of aliases (1 query) and then correlate to resolved alias references. This is because the incomplete ARP indication (all-zeros MAC address) does not work the same way a completed ARP cache entry does. Installation source path does not exist:. The highest version of SSL/TLS to allow in SSL sessions: ssl-3. 100 (No server in my environment has this IP configured but the Proxy ARP entry will allow the firewall to manage and NAT the packets sent to that IP). The MAC address associated with the ARP table entry for the IP next hop may or may not currently be populated in the VPLS Layer 2 FIB table. Linux will automatically add a nonpermanent proxy arp entry when it receives a request for an address it forwards to and proxy arp is enabled on the receiving interface. You can not send data to a IP that does not exist. How do you show the full ARP table for your machine? Capture a printout of what it is. This attribute can have the following values: Clear Text: The passwords are stored in clear text. An IP address can be assigned to the unit using arp/telnet or arp/ping or rarp protocols. If an ARP entry exists for the specified IP address, the switch uses the associated MAC address and identifies the physical path. • MGate could not drop unnecessary RTU bytes. Windows 95/98/2000 4. A Gratuitous ARP is an ARP Response that was not prompted by an ARP Request. This is not a Q&A section. When you start to type [[, if the page exists, you'll be able to select it from the list. set bridge-domain arp entry Summary/usage. Capture the ARP request and reply from the output. ATF_USETRAILERS is obsolete and should not be used. x to the network processor. once selectivity has been performed, even though the entry may be in abi status, a replacement of the entry by the broker through abi is not allowed. rsp Files and also for uninstall. Non-IP traffic: All non-IP traffic is processed by the CPU. If a route associated with the ARP entry already exists, this event is informational only. Advertisements do not imply our endorsement of that product or service. An IP address can be assigned to the unit using arp/telnet or arp/ping or rarp protocols. Any system can spoof a reply to an ARP request Receiving system will cache the reply Overwrites existing entry Adds entry if one does not exist. This can be misunderstood as a connectivity issue with neighboring routers. 2504 Wireless controlller, Adding APs not having any luck Authorization entry does not exist in AAA server. Some load balancers respond to ARP requests with their physical MAC address in the L2 portion of the response, and a virtual MAC address in the L3 portion. Types of Attacks Mike Beekey. If this entry exist ARP Module will give this mac address to Ethernet driver then a. rarpd daemon is not running on the server. If the source MAC address does not exist, it is added to the table along with the incoming port number. Traffic capture (tcpdump) on the Security Gateway shows that the Security Gateway responds to all ARP Requests on a connected subnet with its own MAC address. OPTIONS-a Display all of the current ARP entries. If an entry does not exist, the function forces the TCPnet system to resolve and cache the MAC address into the internal ARP table buffer. Thanks guys!. Instead, configure a static ARP cache entry [see set ip arp], or a static ip6 neighbor [see set ip6 neighbor]. PROPLUS Type: 27::InstalledProductStateCorrupt. The dynamic entry stays in the table as long as traffic flows occasionally. During the Installation of SP1 (only Console) SCOM 2012 to SCOM 2012 SP1 there was a "Rolling back Action" and SCOM 2012 was stopped working. Steven Davidson Mar 8, 2014 3:08 PM ( in response to Arjun ) If you're pretty sure of the switch (you say 90%) but don't know the exact port then what I would do is issue the 'show mac address-table interface' command on each up/up port on that switch until you find one that doesn't have any mac. Pharming N. ARP entry not removed during Previous Version Uninstallation Post by jweksej » Wed Jun 27, 2007 2:03 pm The entry remains with the icon reverted to default. For example, a host can not only update an existing ARP table entry, it could create an ARP table entry if one does not exist. If you configure an IPv4 protocol VLAN that does not include the ARP VLAN protocol, the switch displays the following message which indicates a protocol VLAN configured with IPv4 but not ARP: HP Switch(config)#: vlan 97 protocol ipv4 IPv4 assigned without ARP, this may result in undeliverable IP packets. From what I can gather from the router's user interface, I cannot add a static ARP entry from it, however I have read that it is possible to add such an entry by using telnet to log in to the router. entry does. A communicates to B. + Cannot delete a subkey tree because the subkey does not exist. DNS Poisoning O. This seems mostly useless in home networks, so you can save about 5 seconds on every connect by adding the following line to /etc/dhcpcd. Follow these steps to add a port for a multicast ARP entry in system view:. Auxiliary Function The auxiliary function for ZXR10 devices is as follows. This assures that if host B exists (which at this point, the switch does not know yet), that it will receive it. Basically, the all-zeroes MAC in ARP table is there merely as a convenience for the router administrator. If the multicast ARP entry exists and the same port exists, the switch will not add the port. For subscriber interface configurations, the IP address–MAC address pair must have a matching source prefix that already exists on the subscriber interface. ==On page 379, for ARP parameter, change the first sentence of ==the Note to read as follows: ==from: The ARP counter data will not reflect activity for any devices which support ARP offload. I therefore disconnect from the wireless network, and my wireless-interface default router goes away. ThrowArgumentException(ExceptionResource resource) at Microsoft. To do this, you can call the following function: DWORD RasValidateEntryName(LPWSTR lpszPhonebook, LPWSTR lpszEntry);. Finally once the computer has gone through the ARP request it now has all the necessary information to send the DNS query to the router to find out what IP address that the web page has got. Take care, Jarek EDIT: I was wrong when I said that the ARP entry was not added by my software. The neigh/* sysctls did not exist before Linux 2. You can not send data to a IP that does not exist. Explain each column of what is printed. When you add a new entry, if the entry IP address not exist in the ARP table, the entry will be added at table; otherwise, if the entry IP address already exists in the ARP table, the entry will be updated. I'm playing around with scapy and wireshark and I have sent a packet to a destination that does not exist (10. In this case, it does not sound. I noticed recently that the machine is producing ARP requests looking for an IP address that does not exist. Why does the target of a nmap scan, where the target does not exist get entered into the arp cache? nmap -v -P0 -sT 192. • DSSP health check does not expect any parameters. This attribute can have the following values: Clear Text: The passwords are stored in clear text. This means that the Layer 3 forwarding engine can't forward the packet in hardware because of the missing Layer 2 next-hop address. - If an ARP entry does not exist, the Layer 2 traceroute utility sends an ARP query and tries to resolve the IP address. I didn’t even know this file existed and although everything si not fixed with the NIC atleast all apps poin to the right interface and it holds an IP address instead of jumpin to dhcp all the time or shoeing “The interface does not exist” Very annoying message that. Each time the device is reseted or ip is accessed from the admin panel (eg show connected devices) the permanent arp entry reverts back to a temporary one. During this step, ISG will look up the software ARP table to confirm the software ARP entry of the outgoing interface. If an optional name is not specified, the switch assigns a name in the default format VLAN n, where n is the vid assigned to the VLAN. If an ARP entry does not exist, the FIB entry is marked as "CEF glean", and the entry is known to be in the CEF glean state. If not, it sends out an arp request (a "who has") to find out which MAC address is. Even though the profiler does not individually track functions at depth greater than max_depth, the time spent in such functions is charged to the ancestor function at depth max_depth. entry does not exist. Unable to read config file. By default, most. Each computer has a separate ARP table for each of its Ethernet. Use dictionary indexer to access individual item. I'm trying to create a service to a memcached service sitting on one of our servers by following this documentation:. This is a greenfield for attackers, and remotely exploitable firmware could get them there sooner rather than later. Thanks for the info I struggled forever with wierd behaviour after reboot with my NIC until I found this info. commands in a batch file and use. The ARP command only works once. Types of Attacks Mike Beekey. Targets do not need to be met as with a vendor ARP. It's when I add a second statement for an additional "if exist" (either 2010 or 2013) that nothing happens. When you add a new entry, if the entry IP address does not exist in the ARP table, the entry will be added to the table. This causes packets destined to those addresses to be flooded because a filter database entry will not exist for the virtual MAC address. - Source: mscorlib - Stack trace: at System. • the bfsd is not running; go to 9. VLAN is the VLAN where the IP address was learned or specified. Try to run it with “perl -c av. If the server does not send an ARP Request packet to Switch Module A, Switch Module A still maintains the ARP entry on Port2. R1 now has a routing entry for the 172. Now i need to select data from another table and insert it into this one, but what i would liket o do is search the table first to check if there is a row that is present before i insert it. If a route associated with the ARP entry already exists, this event is informational only. See details for more information. This is often caused by Network Load Balanced Servers without a corresponding switch configuration. This example shows how to ping a remote host from normal executive mode: Switch# ping host1. You can start sending and receiving tcp packets altough that connection does not actually exist in your local system. xml file at: C:\Program Files\Common Files\Microsoft Shared\OFFICE14\Office Setup Controller\Publisher. – If an ARP entry exists for the specified IP address, the switch uses the associated MAC address and identifies the physical path. PROPLUS Type: 27::InstalledProductStateCorrupt. Even ARP didn’t work at all. When you add a new entry, if the entry IP address not exist in the ARP table, the entry will be added at table; otherwise, if the entry IP address already exists in the ARP table, the entry will be updated. I'm using an elevated prompt. I've done some revision in order to make the whole thing flow as a stand-alone document and I've also made some revisions to the example. The dynamic entry stays in the table as long as traffic flows occasionally. To remove an entry, you need only the IP address to identify the entry on the NIC interface. However, my system does not automatically revert to my Ethernet default-router entry; DHCP does not work that way. destination address. *dtlArpTask: Jun 15 15:47:23. If the /etc/tftpaccess. It has been replaced by a protocol called NDP (Neighbour Discovery Protocol) Proper IPv6 auto-configuration of networks can provide an equivalent in the IPv6 address itself. If it does not exist, you can create it as follows: under SuSE, Red Hat or CentOS: /etc/init. DirectoryServices. Normal Xcopy will reset read-only attributes. The 939 layer2+3 value was added for bonding version 3. When there is a communication happening, Windows sends packets to the fake MAC and fakeIP and later we change it to real ones in a driver. (Notice that the “command prompt” here implies telnet as telnet is the only way to remotely access RA) Question 4. Do Not waist your money on anything Meraki has its name on. This is usually caused by a badly written program that doesn't properly uninstall itself. The OpenIPMI-tools package will be required later, as. If it does exist, then reduce ttl and update checksum. If no ARP request it received by the system conducting the ARP query the arp table does not have a valid entry for that IP. application, Culture=neutral, PublicKeyToken=0000000000000000, processorArchitecture=msil. Looking east from the (free entry) Severn View observation tower. Ethernet LAN Attacks 1. Check permissions and then retry installing. NET Framework setup troubleshooting steps do not help How to uninstall an application when it does not appear in Programs and Features list What versions of the. does not have to ARP for it. If the entry exists, make sure that it is the correct MAC address/IP address mapping in case it's been corrupted, or someone else has responded on behalf of the host (eg. So your client is unable to even craft an ICMP packet, destined to the "would be" MAC address of the IP you are trying to ping. Following failure messages were detected: + ARP entry 9204f5692a8faf3b does not exist. If an entry does not exist, the function forces the Network Core to resolve and cache the IP address into the internal ARP table buffer. The arp program displays and modifies the Internet-to-MAC address translation tables used by the address resolution protocol (see arp(7P)). dhcpcd contains an implementation of a recommendation of the DHCP standard (RFC2131 section 2. that that network (mounted on that interface) doesn't exists, or has serious troubles. arp_dev is a zero-terminated string which names a device. that the destination is not local, will use the ARP entry in the ARP table OR if an entry does not exist, will ARP for the MAC of the default gateway on RA. It will at least get a source IP.