Date: Tue, 18 Aug 1998 18:15:43 +0200 (MET DST) From: Nick Hibma <nick.hibma@jrc.it> To: FreeBSD hackers mailing list <hackers@FreeBSD.ORG> Subject: kern/2858: FreeBSD NFS client can't mount filesystem from dual-homed machine Message-ID: <Pine.GSO.3.95q.980818180314.7644B-100000@elect8>
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[Problem -> solution -> question] The problem in short is described as follows. Host A is dual homed and is connected to network X and Y. Host B, a client of NFS server A, is connected to network X but NOT to Y. Let's say we do the following X=10.1.1 Y=10.2.1 AX=$X.124 AY=$Y.124 BX=$X.129 If you now have a line similar to $AY:/usr/src /usr/src nfs rw 0 0 in the $BX:/etc/fstab file, than the computer will hang as soon as it tries to mount /usr/src. Mounting $AX:/usr/src /usr/src nfs rw 0 0 will cause no grief. The problem is that the client sends a request to the 'far' address but gets an answer from the 'nearby' address and waits indefinitely for an answer. If you look with tcpdump on the wire you see however that an ICMP message is sent out to notify the server of the fact that something is wrong. Solution: Only mount from nearby addresses. This a stupid bug as it takes ages to figure. Second, it is a problem when you have a server that acts as an NFS server and router at the same time (like we have in a setup of 12 servers). One thing I would like to know whether there is a simple solution to this, like accepting answers from ANY of the IP addresses of the NFS server, or checking the returned IP address for its matching with the NFS server that we were trying to connect to? There is a bugfix suggested in the discussion of kern/2858, dated March 12th 1998, but has obviously not made it into 2.2.6. (not looked at 2.2.7). Regards, Nick -- building: 27A address: STA-ISIS, T.P.270, Joint Research Centre, 21020 Ispra, Italy tel.: +39 332 78 9549 fax.: +39 332 78 9185 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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