MAN page from Trustix arpwatch-2.1a11-2tr.i586.rpm
Section: Maintenance Commands (8)
Updated: 8 October 2000Index
arpwatch - keep track of ethernet/ip address pairings
keeps track for ethernet/ip address pairings. It syslogs activityand reports certain changes via email.Arpwatch
(3)to listen for arp packets on a local ethernet interface.
The-dflag is used enable debugging. This also inhibits forking into thebackground and emailing the reports. Instead, they are sent tostderr.
The-fflag is used to set the ethernet/ip address database filename.The default isarp.dat.
The-iflag is used to override the default interface.
The-nflag specifies additional local networks. This can be useful toavoid "bogon" warnings when there is more than one network runningon the same wire. If the optionalwidthis not specified, the default netmask for the network's class is used.
The-Nflag disables reporting any bogons.
The-rflag is used to specify a savefile(perhaps created bytcpdump(1)orpcapture(1))to read from insteadof reading from the network. In this case,arpwatchdoes not fork.
Note that an emptyarp.datfile must be created before the first time you runarpwatch.
Here's a quick list of the report messages generated byarpwatch
- new activity
- This ethernet/ip address pair has been used for the first time sixmonths or more.
- new station
- The ethernet address has not been seen before.
- flip flop
- The ethernet address has changed from the most recently seen address tothe second most recently seen address.(If either the old or new ethernet address is a DECnet address and itis less than 24 hours, the email version of the report is suppressed.)
- changed ethernet address
- The host switched to a new ethernet address.
Here are some of the syslog messages;note that messages that are reported are also sysloged.
- ethernet broadcast
- The mac ethernet address of the host is a broadcast address.
- ip broadcast
- The ip address of the host is a broadcast address.
- The source ip address is not local to the local subnet.
- ethernet broadcast
- The source mac or arp ethernet address was all ones or all zeros.
- ethernet mismatch
- The source mac ethernet address didn't match the address insidethe arp packet.
- reused old ethernet address
- The ethernet address has changed from the most recently seen address tothe third (or greater) least recently seen address.(This is similar to a flip flop.)
- suppressed DECnet flip flop
- A "flip flop" report was suppressed because one of the twoaddresses was a DECnet address.
/usr/operator/arpwatch - default directoryarp.dat - ethernet/ip address databaseethercodes.dat - vendor ethernet block list
Craig Leres of theLawrence Berkeley National Laboratory Network Research Group,University of California, Berkeley, CA.
The current version is available via anonymous ftp:
Please send bug reports to arpwatchAATTee.lbl.gov.
Attempts are made to suppress DECnet flip flops but theyaren't always successful.
Most error messages are posted using syslog.
- REPORT MESSAGES
- SYSLOG MESSAGES
- SEE ALSO
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