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- $HOME/.netrc
- Specify automatic login information
$HOME/.rhosts - Defines
which client USERS are NOT required to supply a login
password
- ping
- Sends an ICMP ECHO_REQUEST
- finger
- Lists the current users logged on
- iptrace
- Debug trace utility for ip packets
ipreport - Generates a packet
trace report
- spray
- Sends a specified number of packets
- no
- Configures network options
- netstat
- Show network statistics
- nfsstat
- Lists statistics about network file system
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Assume
a configuration as follows...
SOURCE ADDR = 128.100.0.1
DESTINATION ADDR = 128.96.69.100
SUBNET MASK = 255.255.0.0
BROADCAST MASK = 128.100.255.255
In this
case, the DESTINATION PACKET will go to the DEFAULT
GATEWAY ADDRESS
Assume
a configuration as follows...
SOURCE ADDR = 128.100.0.1
DESTINATION ADDR = 128.96.69.100
SUBNET MASK = 255.255.255.0
BROADCAST MASK = 128.255.255.255
In
this case, the DESTINATION PACKET will NOT go to the
DEFAULT GATEWAY ADDRESS and will be routed within the
local network.
To determine
via the SUBNET MASK if a destination packet goes to the GATEWAY
node or not, follow these simple rules:
- Perform
a LOGICAL AND of the destination address of the mask of the
local subnet address
- Perform
an EXCLUSIVE OR on the result of the previous operation and
the local net address of the local interface (eg., source address)
- If the
result of the previous operation is a ZERO, the destination
is assummed to be reachable directly through one of the local
interfaces ELSE the packet is forwarded to the DEFAULT GATEWAY
ADDRESS.
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Automatic
login information for the ftp and rexec commands.
syntax:
machine <hostname> login
<username> password <password>
If this file
contains a password entry (optional), the
file permissions must be set to 600 (rw for owner only)
or else the error message rshd: 0826-813
Permission is denied.
is generated.
The file .netrc
must exist on the client that your executing the ftp or rexec
command from and the <hostname> must specify the name of
server to connect to.
For FTP only,
you can initiate file transfers via a macro definition (up to
16 macros can be defined). This file resides on the client machine.
An example
of the contents of a .netrc file...
machine
sys8 login transfer password
now macdef init
get /tmp/database.log /tmp/log/database.log
quit
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Defines which
client users are not required to supply a login
password for the rcp, rlogin, or rsh commands using a user
account on the server. The file resides on the server machine
under the home directory of the user account being logged into.
An ALIAS entry cannot be specified.
syntax: <hostname>
<username>
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Defines which
clients are permitted to execute commands by the lpd, rlogind,
rcpd, or rshd daemons without supplying a password.
syntax:
<hostname>
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Defines which
clients are permitted to print jobs to the print server.
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arp
- Address Resolution Protocol
Displays the
translation table between TCP/IP addresses and network addresses.
This physical address is six bytes long and is unique for every
network board. The first three bytes of the address represent
a vendor's ID. The last three bytes are assigned by the manufacturer.
Some examples...
NOVELL 00 00 1B
NOVELL 08 00 14
3COM 02 60 8C
SUN 08 00 20
IBM 08 00 5a
DEC AA 00 04
Note
that an IP address is really assigned to a network interface and
not a host. A host may have more than 1 network interface as illustrated
by the output of the netstat -i command.
Useful tool
for debugging network problems.
- For example,
if you are using the DOS SERVER daemons to connect PCs to the
RS/6000 and connections aren't being made, check the arp table
to see if there is a hostname entry for the name of the PC you
are connecting from. If there is an entry in the arp table,
then you know that packets are getting across and the problem
lies with the DOS SERVER or PC DOS CLIENT software.
- Further,
you may have configured two or more hosts with the same internet
address. If this is the case, its possbile that one connection
may get hung. That's because the entry in your arp table gets
overwritten by the new connection. View the arp table and you'll
find that the internet address may now be bound to a new physical
network address. The connection that is hung, will not show
the correct physical address for that IP address. It shows the
new physical address of the machine that has the same IP address
of the previous connection.
- Another
reason to use this utility for a debugging tool is to show what
network adapter card address is mapped to an internet address.
If by chance, you have two nodes on your
network with the same internet address, you will have periodic
problems keeping a connection to one of those two machines until
a unique internet address is assigned to each machine.
Examples:
arp -a (Displays
all addresses that have been translated by the address resolution
protocol.)
Outputs: dospc (193.0.0.8) at 10:0:5a:2b:69:64
[token ring]
eai1 (192.0.0.3) at (incomplete)
An incomplete
entry in the network address field means the node in question
could not be contacted. Probably reasons are:
- node
doesn't exist on the network
- node
isn't connected to network
- network
is not terminated properly
- problem
with network cabling
- software
on destination host has a bug
arp
-d dospc (Remove the dospc entry from the arp
table)
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Lists the
current users logged in from remote machines, including username,
hostname, idle time, and so on
Example:
finger -i (alias f -i)
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This command
returns the internet address when a hostname is specified or the
hostname when the internet address is specified.
| Examples |
What
it does |
| host
www.ahinc.com |
www.ahinc.com
209.218.236.72 |
| host
209.218.236.72 |
www.ahinc.com
209.218.236.72 |
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Sets or displays
the name of the host system
| Examples |
What
it does |
| hostname |
Displays
the current hostname value |
| hostname
rs520 |
Sets the name of the machine to rs520. Make
sure that you set the system name to rs520 by executing the
uname command |
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Sets or displays
the system name
| Examples |
What
it does |
| uname
-S rs520 |
Sets
the system name |
| uname
-a |
List
the system name |
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Configures
or displays the network interface parameters for a tcp/ip network
| Examples |
What
it does |
| ifconfig
en0 |
Indicates
if the en0 interface is up and running.
en0: flags=2000063<UP,BROADCAST,NOTRAILERS,RUNNING,NOECHO>
inet 192.0.0.1 netmask 0xffffff00 broadcast 192.0.0.255 |
| ifconfig
en0 up |
Before
this command is executed the state of the en0 interface is
down (doesn't show UP):
en0: flags=2000062<BROADCAST,NOTRAILERS,RUNNING,NOECHO>
inet 192.0.0.1 netmask 0xffffff00 broadcast 192.0.0.255
After this command is executed the state of the en0
interface is:
en0: flags=2000063<UP,BROADCAST,NOTRAILERS,RUNNING,NOECHO>
inet 192.0.0.1 netmask 0xffffff00 broadcast 192.0.0.255 |
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1) ifconfig
en0 down
2) ifconfig en0 detach |
Adapter
statistics for the ethernet card get reset to zero. See the
netstat -v display for further
information. |
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Debug trace
utility for IP packets
| Examples |
What
it does |
| iptrace
-a -s 193.0.0.1 -i en0 network.log |
All
TCP/IP packets that originate from host address of 193.0.0.1
with a ethernet network interface (en0) will be logged to
the file network.log. |
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Generates
a packet trace report generated from the iptrace
facility
Example:
ipreport network.log
Dumps the packets that were trapped from the iptrace
session in ascii format for inspection. Must
kill the iptrace process before this report can be displayed.
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| Examples |
What
it does |
|
host ahinc
or
arp -a |
If the
arp -a or host
commands hang, usually means the name server daemon (/etc/named)
is not running. Use the command ps
-ef|grep named to check if named is running. |
| Telnet
login responce is very slow. |
Make
sure the /etc/resolv.conf file has a valid entry
in it and the /etc/hosts file has the appropriate
entries for all known client nodes.
Contents
of an example of a /etc/resolv.conf:
nameserver
192.168.1.1 domain ahinc.com
When
using the named process, each node should have at least
the loopback and local host name defined in the /etc/hosts
file.
Contents
of an example of a /etc/hosts file.
127.0.0.1
loopback localhost
192.168.1.1 ahinc |
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Shows network
statistics
| Examples |
What
it does |
| netstat
-f inet |
List
statistics of AF_INET address family for remote communications |
| netstat
-f unix |
List
statistics of AF_UNIX address family for local communications. |
| netstat
-m |
Shows
current network interfaces that are up and running.
- If
a network interface shows an asterik next to it (en0*),
this means your interface is down. Use the ifconfig
command to bring the network back up.
- If
the Ierrs field (input errors) is nonzero, this
means their are no more kernel memory buffers left to
store an incoming frame or indicates a frame error has
been detected.
- If
the field Coll field has a colllision rate greater
than 1% of the packets sent/received, then a serious network
problem exists.
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| netstat
-r |
If the non-loopback entry has a G in Flags field (g=gateway),
then the ping command may hang. Change the Flags field
to U only. Make sure the ROUTED
daemon running. To start: startsrc
-s routed |
| netstat
-nr |
Route
Tree for Protocol Family 2: |
netstat
-sr
netstat -s |
Displays
statistics for each protocol (ip, icmp, tcp, udp) |
| netstat
-v |
Shows
statistics about network interface cards installed.
- If
the Xmit Carrier Lost field contains a non-zero
value, you most likely have a problem with your ethernet
cable.
- The
errpt command should
contain entries for the eth?
device where
- ?
is=first ethernet adapter
- 2=second
ethernet adapter, etc
- These
error entries should cycle between ENT_ERR6 and ENT_ERR2
and reference problems with the ethernet cable itself.
- Use
the ping command to
further identify the problem and also validate through
diagnostics that the network adapter card is good.
- XMIT
MAX COLLISIONS gets bumped when the transmitter has tried
to transmit a frame 16 times and each of the 16 failed
due to a collision.
- XMIT
UNDERRUN gets bumped when the transmitter is getting under-runs.
- XMIT
TIMEOUTS gets bumped when the transmitter on the adapter
times out while trying to transmit.
- PACKETS
TOO LONG get bumped when a packet is detected that is
larger than the interface can handle (en0 of 1514+ bytes)
- RECEIVE
DMA LOCKUPS gets bumped when the adapter card has detected
itself in a lockup state. The microcode will then restart
the 82586 to correct this problem and get things working
again.
- INTERRUPTS
LOST is the number of interrupts which are not caught
by that NIC device driver. When this counter is not 0,
a problem exists with the device driver or NIC.
- NO
MBUF ERRORS is the number of failed receive MBUF requests
from the NIC device driver.
- RECV
OVERRUN COUNT is stating the the NIC is getting overrun.
This is not a big problem unless you see many of these.
New microcode/EPROMS may reduce this number.
- RECV
PKTS DISCARDED is stating packets are being received that
can't be matched to the TYPE field. For Ethernet cards,
the type of frames being received would only be 802.3/Ethernet
Ver 2.0
- PACKETS
REJECTED NO NETID is stating that a packet came in at
the LLC level and it didn't have a SAP bound to send it
up to. In other words, the device driver didn't recognize
the packet type that came in. Could be because your co-existing
with a Novell network using IPX and your using TCP/IP.
|
| netstat
-v |
chdev
-l ent0 -a receive_size=60 |
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Lists statistics
about network file system (NFS) and remote procedure calls (RPC).
Also distinguishes between client and server information.
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Configures
network options. The no command ONLY
operates on the currently running kernel. This command must be
run each time the system is rebooted.
| Examples |
What
it does |
| no
-o tcp_ttl=40 |
Specifies
the time to live for TCP packets (40 ticks). |
| no
-o thewall=3000 |
Sets
the size of the mbuf pool to 3 MB (default is 2 MB). If requests
for mbufs has been denied, this should prevent requests from
being denied. |
| no
-a ipforwarding=0 |
Turns
off IP forwarding |
no
-o tcp_sendspace=8192
no -o tcp_recvspace=8192 |
Increasing the buffers to 8k, performance gains of
up to 10-20% have been attained. |
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Sends an ICMP
ECHO_REQUEST message to a network host every second.
| Examples |
What
it does |
| ping
rs520 |
Quick
way to determine if the network host you wish to communicate
with is either up and running or is configured properly. If
ping intermediately reports back packets (5 packets sent,
1 is lost, 2 packets sent, 1 lost, etc), suspect a bad connection. |
| ping
192.0.0.255 |
Generates
responses from all the other nodes connected on a class C
network. If you wish to see what nodes
are up and responding on your network, this is a simple test
to run. |
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Sends a specified
number of packets over the network and reports back performance
statistics.
| Examples |
What
it does |
| /usr/etc/spray
AIX -c 1000 -l 1400 -d 1 |
Send
1000 packets to the host named AIX with a delay of 1 micro-second,
where each packet sent is 1400 bytes. This uses the RPC protocol. |
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