Sockinfo
sockinfo lets the system administrator or programmer obtain more information
on TCP, UDP, ICMP, RAW, and IGMP protocol control blocks (PCB) in a format
similar to netstat(TC). sockinfo identifies and shows:
- the process, file descriptor in the process, user, and tty device
(if present) associated with the PCB.
- all TCP options (SO_KEEPALIVE, SO_LINGER, etc.) set on the connection.
- TCP external state information like ESTABLISHED or SYN_SENT as well as
internal state like ISCONNECTED and CANTRCVMORE.
- TCP timers in effect. You can watch retransmissions, keepalive timers, and
other timers expire.
- TCP internal parameters (sequence numbers, window sizes, etc.).
- where the last UDP packet was sent to and how long ago that was.
- the route and interface the PCB is currently using.
- when route was added to routing table and how it was added.
- any process sending ICMP packets.
- any process sending RAW packets.
- any process sending IGMP packets (OpenServer 5.0 only)
- lines pertaining to netbios.
- lines pertaining to in-kernel NFS (these are guesses on ODT3.0 but
accurate on OpenServer 5.0).
- UNIX domain sockets
- the upstream driver
(socket for BSD socket programs, timod for TLI programs,
ktmod for NFS, or netbios)
sockinfo can also limit its output to one particular process or PCB and
display the information at fixed intervals for further analysis.
sockinfo has been compiled for SCO UNIX 3.2.4.2/TCP1.2.1 (ODT3.0, OSES3.0)
as well as Open Server 5.0.
sockinfo requires read access on /unix and /dev/kmem in order to obtain the
above information.
Installing sockinfo:
sockinfo can be copied into and run from any directory. Copy sockinfo to
an appropriate directory (such as /bin or /opt/SCO/TLS/) and type:
# chgrp mem sockinfo
# chmod 2511 sockinfo
This allows any user to run sockinfo without being root. If you make sockinfo
setuid root users will not be able to use the -h or -n options; these are
reserved for user root. Note that sockinfo does not need to be setuid root
to work and making sockinfo setgid mem as described above is preferred.
Running sockinfo:
type sockinfo without any arguments to see a usage line.
Interpreting sockinfo output:
While sockinfo mimics netstat as much as possible, some fields with some
options may be unfamiliar to the user. When in doubt, grep for the field
name in /usr/include/sys, /usr/include/sys/net, or /usr/include/sys/netinet.
Sockinfo shows fields values literally: some information such as
dates or aging information may not be correct until data has actually been
sent, or a process may not exist for all PCB's, etc.
Caveat for -h option on OpenServer 5.0:
As root, if you use the -h "hurry" option on OpenServer 5.0 you will obtain more
accurate information if you are concerned with timers or are trying to monitor
a process which is rapidly manipulating/creating connections. To do this,
sockinfo will have substantially higher priority than other user processes as
shown with ps -efl; this will degrade the performance of other runnable
processes on the machine. This effect is worse when using the -l "loop" option
since sockinfo will only stop running for the number of "interval" seconds you
specify. In fact, with -h -l 0, sockinfo will completely "hog" the CPU and
prevent nearly all other user processes from running!
To lessen this effect, set the environment variable SOCKINFO_PRIORITY
to an integer number between 1 and 127 before running sockinfo.
The value 1 means sockinfo will have a low priority while 127 means that
sockinfo will have an extremely high priority as far as the scheduler is
concerned. You will see the new process priority with ps -efl.
OpenServer 5.0 note:
If a dynamic kernel table size grows while sockinfo is running you may see
strange behaviour. restart sockinfo and the problem will disappear.
I intend to add dynamic table support in a future release.
The format used to display TCP control block information will be cleaned up
in a future release.
For performance reasons, sockinfo will not work if kernel auditing is active.
Due to licensing restrictions, source for sockinfo is not available.
I am interested in feedback(good and bad!) as well as any bugs you find.
Nathan Peterson
nathan@sco.com
30 June 1995