Technical data

Troubleshooting Techniques and Tools
1.2 Isolating Problems
The UDP or TCP protocol information is not displayed. This is generally not
important for UDP; however, it can be important for TCP. If the
-m and -v options
are in effect, both RPC and TCP decoding are done. For example, the UNIX
command
showmount -e srv generates information such as the following:
clnt.3123f473 > svc.pmap-v2: 56 call getport prog "mount" V1 prot TCP 0
(ttl 29, id 19672)
svc.3123f473 > clnt.pmap-v2: 28 reply getport 892
(ttl 30, id 31644)
clnt.1032 > svc.892: S 25280000:25280000(0) win 32768 <mss 1460,nop,wsca>
(DF) (ttl 59, id 19674)
svc.892 > clnt.1032: S 483136000:483136000(0) ack 25280001 win 33580
<mss 1460,nop,wscale 0> (ttl 60, id 31645)
clnt.1032 > svc.892: . ack 1 win 33580 (DF) (ttl 59, id 19675)
clnt.2f221c23 > svc.mount-v1: 40 call return export list
TCP: clnt.1032 > svc.892: P 1:45(44) ack 1 win 33580 (DF) (ttl 59, id 19)
svc.2f221c23 > clnt.mount-v1: 184 reply export
"/usr": "client" "clnt"
"/build":
...
TCP: svc.892 > clnt.1032: P 1:189(188) ack 45 win 33580 (ttl 60, id 3164)
clnt.1032 > svc.892: F 45:45(0) ack 189 win 33580 (DF) (ttl 59, id 19679)
svc.892 > clnt.1032: . ack 46 win 33580 (ttl 60, id 31649)
svc.892 > clnt.1032: F 189:189(0) ack 46 win 33580 (ttl 60, id 31650)
clnt.1032 > svc.892: . ack 190 win 33580 (DF) (ttl 59, id 19681)
The following is another NFS sample:
sushi.6709 > wrl.nfs-v2: 112 call readlink fh 21,24/10.731657119
wrl.6709 > sushi.nfs-v2: 40 reply readlink "../var"
sushi.201b > wrl.nfs-v2: 144 call lookup fh 9,74/4096.6878 "xcolors"
wrl.201b > sushi.nfs-v2: 128 reply lookup fh 9,74/4134.3150
The example shows the following sequence of communication:
• In the first line, host sushi sends a transaction with ID 6709 to host wrl .
(The number following the src host is a transaction ID, not the source port.)
The request was 112 bytes, excluding the UDP and IP headers. The operation
was a readlink (read symbolic link) on file handle ( fh ) 21,24/10.731657119.
(In some cases, the file handle can be interpreted as a major and minor device
number pair, followed by the inode number and generation number.) Host
wrl
replies with the contents of the link.
• In the third line, host sushi asks host wrl to look up the name xcolors in
directory file 9,74/4096.6878.
• The data displayed depends on the operation type. The format is intended to
be self explanatory if read in conjunction with a protocol specification rpcgen
.x
file.
If the -v (verbose) option is given, additional information is displayed.
If the
-v option is given more than once, more details may be displayed.
Note that RPC requests are very large and much of the detail is not displayed.
Property list information may also be obtained using tcpdump . For example:
node1.abc.com.da31fba5 > node2.abc.com.proplist-v3: \
276 call proproc3_get OSF/1 fh 8,18434/1.4 mask:-1 11 entries
node2.abc.com.da31fba5 > node1.abc.com.proplist-v3: \
296 reply proproc3_get status OK 368 bytes 11 entries
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