AIX for System Administrators_Commands

Commands

NETWORK CONFIGURATION AT BOOT TIME:

1. /etc/rc.net

Configures and starts TCP/IP interfaces. Sets hostname, default gateway and static routes.(it is called by cfgmgr)

then during initialization the file /etc/inittab is called. There are 2 entries:

...

rctcpip:23456789:wait:/etc/rc.tcpip > /dev/console 2>&1 # Start TCP/IP daemons

rcnfs:23456789:wait:/etc/rc.nfs > /dev/console 2>&1 # Start NFS Daemons

...

2. /etc/rc.tcpip

starts TCP/IP daemons (sendmail, portmap, inetd, etc., and other daemons: syslogd, lpd ...)

3. /etc/inetd.conf

when inetd started, it reads its configuration from this file

contains the name of the services that inetd listens for requests and starts as needed

PORTMAP DAEMON:

The portmap daemon converts remote procedure call (RPC) program numbers into Internet port numbers. (like in the case of NFS)

When an RPC server starts up, it registers with the portmap daemon. The portmap daemon knows the location of every registered port on

the host and which programs are available on each of these ports. When a client sends an RPC to the server, the portmap daemon answers

to the client which port to send the call to. Portmap daemon listens on port number 111.

It is started from /etc/rc.tcpip before inetd and the RPC servers (e.g. nfs). Thus, when the RPC servers start they can register with

portmap.

INETD DAEMON:

The /usr/sbin/inetd daemon provides Internet service management for a network. It reduces system load by invoking other daemons. The

inetd daemon listens for connections on certain Internet sockets (info in /etc/inetd.conf) and handles those requests.

The inetd daemon is a subsystem that controls the following daemons (subservers): ftpd, fingerd, talkd, telnetd ...

/etc/inetd.conf inetd configuration file (if changed by an editor, run refresh -s inetd)

smitty inetd updates automatically the /etc/inetd.conf

lssrc -ls inetd shows details of subservers started in inetd

stopsrc -s inetd stops the inetd daemon

stopsrc -t ftp stops an inetd subserver

------------------------

NAME RESOLUTION:

You can use several methods to ensure that /etc/hosts file is used before any DNS, if the /etc/resolv.conf file exists.

You can include the NSORDER variable in the /etc/environment file, or you can include a specification line in either the /etc/irs.conf

file or the /etc/netsvc.conf file.

The settings in the /etc/netsvc.conf configuration file override the settings in the /etc/irs.conf file. The NSORDER environment

variable overrides the settings in the /etc/irs.conf and the /etc/netsvc.conf files.

Domain Name Service (DNS):

/etc/resolv.conf contains name servers, if this file exists then we have a domain network, if not then /etc/hosts file is used

/etc/netsvc.conf specify the ordering of name resolution (or NSORDER environment variable can contain this)

(if both exists NSORDER will override netsvc.conf)

bind=DNS, local=/etc/hosts

pl.:

NSORDER=local,bind <--this can be added to /etc/envronment

The /etc/netsvc.conf and /etc/irs.conf files are used by the resolver routines as soon as the files exist

/etc/netsvc.conf configuration:

hosts=local,bind

/etc/irs.conf configuration:

hosts local continue

hosts dns

nslookup <server name> responds similarly to the host command, but it only uses DNS (don't NIS and don't /etc/hosts)

Flat Network:

/etc/hosts contains the hostnames and their address for hosts in the network

host <hostname> searches through the /etc/hosts file, and display the ip address of the hostname

host <ip address> searches through the /etc/hosts file, and display the hostname

To work properly both should give the same result.

------------------------

ADDRESS RESOLUTION:

Internet-to-physical address (MAC address)

arp -a shows the ARP table

the manual of arp command can help

------------------------

VERIFYING OPEN PORTS:

To display TCP/IP application ports (which are opened)

netstat -an lists of opened ports with port numbers (netstat -an -f inet)

netstat -af inet lists all open UDP and TCP ports with service names (not the port numbers)

server ports are in LISTEN state, client connections to or from any port are in ESTABLISHED state

/etc/services contains information about known services and their portnumber (if changing this file: refresh -s inetd)

620,264

PAGEVIEWS

ABOUT

FS

LV

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AIX for System Administrators http://aix4admins.blogspot.mx/2011/05/network-configuration-at-boot-t...

1 of 5 04/05/2013 23:10

------------------------

ROUTING

lsattr -El inet0 shows routings in the inet0 (which is a netwotk device in the kernel (config info for inet0 is stored in the odm)

(you can check with this as well: odmget -q attribute=route CuAt)

netstat -rn shows the routing table. (-r: displays routing statistics, -n: displays the network address as an IP address)

In the routing table:

U - route is up and available

H - route is to a host

G - route is to a gateway

b - route represents a broadcast address

S - manually added??? (Static route: it will come back after reboot???)

A - Active Dead Gateway Detection is enabled on the route

Check both places: netstat -nr and lsattr -El inet0 (odmget -q "attribute = route" CuAt)

Commands:

chdev <--permanent: it will modify inet0 with the new route, it registers a new entry in the ODM

smitty route <--permanent: it calls the command chdev (Destination, Gateway and Netmask should be filled)

route <--temporary: this is valid only until next reboot (does not update the ODM)

ADD/REMOVE with chdev: (permanent)

(when default route is added it can be network route, dest. addres is 0.0.0.0 and network mask can be 0.0.0.0)

(we can add interface name as well, if omitted system will add 1)

add:

chdev -l inet0 -a route=net,-hopcount,0,,0,100.200.200.65

chdev -l inet0 -a route=0,<default gw address> <-this will add the default route

remove:

first check lsattr -El inet0, and copy a line exactly from the output into " ...":

chdev -l inet0 -a delroute="net,-hopcount,0,-netmask,255.255.0.0,-if,en4,,,,50.20.0.0,50.50.80.3"

chdev -l inet0 -a delroute="net,-hopcount,0,,0,100.200.200.65"

chdev -l inet0 -a delroute="net,-hopcount,0,-netmask,255.255.255.240,,,,,-static,50.20.100.80,10.10.3.1"

------------------------

ADD/REMOVE with route: (temporary)

add:

route add 0 9.19.99.11 <--adds default route (0 really stands for 0.0.0.0)

route add -net 100.100.243.0 -netmask 255.255.255.0 100.100.200.209 <--adds network route (route add -net $NETW -netmask $NETMASK

$GATEWAY)

route add -net 9.19.99/22 9.19.98.11 <--adds network route without netmask

route add -host 50.200.100.31 50.200.100.20 <--adds host route

route add 10.200.40.28 10.200.40.1 -active_dgd <--sets dead gateway detection on that route (netstat -nr shows: A if enabled on a

route)

remove:

route delete 50.20/22 50.50.80.3 <--keeps in the ODM

route delete 0 9.19.99.11 <--deletes only the deafult route

route -f clear the routing table (except those created implicitly)

mkdev -l inet0 it will recreate the routes which exist in the ODm (inet0) (it can help, if it was deleted manually)

The route command distinguishes between routes to hosts and routes to networks by interpreting the network address of the destination

address. The optional keywords -net and -host force the destination to be interpreted as given.

If there are more routes (duplicate routes) on host A, you can have some packet loss, when you ping host A from host B. On host A if you

issue many times: route -n get <host B>, you will see interface names (enX) will change, this is due to bad routing)

For Static routes a solution would be:

(instead of using chdev and ODM checking)

1. add the routes with route command

2. Put the routes into /etc/rc.net file (with the same route command)

Look for "Part II - Traditional Configuration," and you will see an area in which you can add routes

This way, you have a flat file that is easily modified, contains the route information in a straightforward way, and doesn't manipulate

the ODM.

To remove all the routes:

(routing table + ODM)

/etc/route -n -f and odmdelete -o CuAt -q "name=inet0 and attribute=route"

------------------------

chdev - changes are effective immediately and across boots

ifconfig, route - changes are active immediately and are effective until reboot

------------------------

DIFFERENT INTERNET SERVICES:

ARPANET BERKLEY SECURE SHELL

secure (not powerful) powerful (not secure) secure and powerful

Remote login: telnet rlogin/rsh ssh

Remote execue: rexec rsh ssh

File Transfer: ftp rcp sftp/scp

------------------------

OTHER COMMANDS:

smitty inet configuring interfaces

smitty tcpip configuring TCP/IP

smitty mktcpip on 1 page you can set: hostname, default gateway, netmask...

smitty hostname sets the hostname (chdev -l inet0 -a hostname=<name>)

lsdev -Cc adapter lists adapters

lsdev -Cc if lists interfaces

lsattr -EHl en0 lists attributes (ez is müxik: lsattr -EHl ent0)

Basics

CPU

I/O - Disk, Adapter

Memory

Network

svmon - RAM

topas - nmon

vmstat - CPU/RAM

VMM concepts

VIO

PERFORMANCE

Adapter

Basics - SAN

Basics - Settings

EMC

Hitachi

HP EVA - SSA

MPIO

SDD

STORAGE

Basics

Commands

IFIX

UPDATE - INSTALL

Basics

Commands

AME - AMS

CDROM - DVDROM

LPM

NIB - LA

NPIV

SEA

Shared Storage Pool

VIOS update/upgrade

Virt. Eth. Ad.

Virt. Proc.-Ent. Cap.

VSCSI

VSCSI - Stor. Pool

VIO

+others

alt_disk

awk - sed

bash

citrix

java

kdb

ksh

locale

multibos

perl

profiles

rbac

Rsh

samba

screen

script

sudo

vi

+EXTRAS


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Labels: NETWORK

lscfg -vpl <device> shows vital product data (e.g. lscfg -vpl ent0)

ifconfig configure and modify properties of network interfaces

ifconfig -a displays information about all interfaces (should be UP and RUNNING)

ifconfig en0 shows attributes of a specific interface (lo0:loopback, en0:ethernet...)

ifconfig en0 up activates network interface (... down: deactivates it)

ifconfig en1 50.20.100.47 netmask 255.255.255.192 configure ip (or ifconfig en0 x.x.x.x netmask y.y.y.y up)

ifconfig en3 10.200.30.106 netmask 255.255.255.0 alias configure alias (ifconfig makes changes only until reboot)

ifconfig en3 10.200.30.106 netmask 255.255.255.0 delete deletes ip from interface en3

chdev -l en8 -a netaddr=50.20.80.4 changes the ip on en8

chdev -l en1 -a netaddr=12.10.10.2 -a netmask=255.255.255.0 -a state=up

chdev -l en3 -a alias4=10.10.6.26,255.255.255.0 adds alias to en3 (last after reboot as well)

chdev -l en9 -a delalias4=10.200.200.136,255.255.255.224 removes an alias (this works as well: ifconfig en1 delete 9.37.207.29)

no -a lists network tuning parameters

ping -c 1 <hostname> sends only 1 packet

ping -f <hostname> floods out packets (it is good for testing the network for handling a lot of traffic)

ping -s <packet size> <hostname> specifies the number of bytes to be sent

rpcinfo -d <pid> deletes registration of a service (clears up the port?)

spray <hostname> -c 100 -l 50 -d 1 sends a specified number of packets to a host (performance statistics)

it uses RPC which is higher level then ICMP (higher layer than ping)

sprayd must be run in host to get respond (inetd.conf)

-c number of packets to send

-l the size of a packet

-d delay time (in microseconds) between sending the packets

-i sends ICMP package not RPC

netstat -rn shows the routing table

netstat -in shows the MAC addresses (and IP addresses) of all interfaces

netstat -v shows device driver information

netstat -v ent2 shows statistical information (it uses entstat, e.g. it is similar to entstat -d ent2)

netstat -v |grep Media shows running speed (100Mbs..., Full duplex) (netstat -v | egrep "ETH|Media|Speed|Link")

netstat -p udp display UDP transport statistics (dropped, socket buffer overflow)

netstat -p tcp display TCP transport statistic (retransmitted: it means cannot ACK before timeout, duplicate packets)

netstat -I en0 2 shows traffic across that interface in 2 seconds intervals

netstat -an display the status of connections to host

route get shows info which interface, gateway ... is used to reach the ip

traceroute shows each router the packets travel through to reach the target host

+with the min., average, max. response time taken to get to that router (* means probe to the next router timed

out)

traceroute <ip> <size> packet size can be added as well (once this was successful:traceroute 100.200.140.55 1456, but with 1457 it

wasn't)

arp -an shows the routing table without name resolution

------------------------

tcpdump -i en0 icmp it will only watch the icmp (ping) traffic on the given interface

tcpdump -i en1 host 50.50.30.8 displays the traffic of en1 which is coming from or going to the given host

tcpdump -n -i en1 host 50.50.30.8 it is the same as above, just without name resolution (more simplified)

tcpdump -i en2 dst host <host> show only data being sent to a specific host

tcpdump -i en2 src host <host> show only packets coming from a specific host

tcpdump -i en2 host <host> port 22 show packet destined for or sent by a specific host on a specific port

tcpdump -w test.pcap -i en4 host 10.120.0.13 shows network traffic (if -w omitted it displays the results on the screen)

-w writes details to file test.pcap (it is not a text file, wireshark can understand it)

-i checks traffic only on specified interface

host only the communication from the given host will be watched

------------------------

iptrace same as tcpdump (tcpdump better)

iptrace usage:

1. iptrace -a -i en1 -s clientip -b -d serverip -p 80 trace.out this will capture both directions on port 80 traffic to file

trace.out

2. generate a test, then run: ps -ef | grep iptrace --> kill -15 <pid>

3. ipreport trace.out>trace.fmt (after this trace.fmt can be read by wireshark)

uname -n display the hostname (-x: displays operating system realease number...)

no -o ipforwarding shows if the host fowards IP datagrams or not (0=not, 1=yes; to change it: no -o ipforwarding=<value>)

Hosts should not forward IP datagrams unless specifically configured as a router

------------------------

Hostname setting:

hostname <any name> changes the hostname until next reboot

chdev -l inet0 -a hostname=<néame> permanent change

------------------------

Who is using my port?

1. netstat -Aan | grep <port number> <-- shows if the specified <port number> is being used.

The hex number in the first column is the address of protocol control block (PCB)

$ netstat -Aan | grep 30542

f10000f303321b58 tcp4 0 0 *.30542 *.* LISTEN

2. rmsock <addr of PCB> tcpcb <-- This shows the process (PID) who is holding the socket. (should be runas root)

$ rmsock f10000f303321b58 tcpcb

The socket 0x3321800 is being held by proccess 692476 (db2sysc).

Note that rmsock, unlike what its name implies, does not remove the socket, if the socket is being used by any process.

It just reports the process holding the socket. The second argument of rmsock is the protocol. (tcpcb in the example indicates TCP.)

------------------------

12 comments:


3 of 5 04/05/2013 23:10

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Anonymous September 20, 2012 at 9:01 PM

Hi,

what is hopcount in route add entry. Also explain t he entries available in route addition command

"net,-hopcount,0,,0,100.200.200.65"

Reply

aix September 20, 2012 at 10:25 PM

Hi,

"man route" says about hopcount:

-hopcount n

Specifies maximum number of gateways in the route.

That example what you gave I usually get from "lsat tr -El inet0", and I copy that line without modific ation to i.e. delroute. But for

decoding it, I guess the first 0 after hopcount rel ates to hopcount and the second 0 means default gat eway (it can be translated to

0.0.0.0)

Anonymous March 19, 2013 at 10:23 PM

Good information

Reply

aix March 19, 2013 at 11:25 PM

:-)

Sri March 29, 2013 at 2:44 PM

Reply


Reply


Hi, I have to add new IP/second IP(124.23.43.22) as the loopback interface, I have settings like below ..

[/]# ifconfig lo0

lo0: flags=e08084b,c0

inet 127.0.0.1 netmask 0xff000000 broadcast 127.255 .255.255

inet6 ::1%1/0

tcp_sendspace 131072 tcp_recvspace 131072 rfc1323 1

==================

Please let me know the command (as permanent and te mporary) to add new IP/second IP as the loopback in terface

Reply


How to add new ip to the loopback interface lo0 as permanent ?

Thanks,

Sri

Reply


What is the command to add new ip to the loopback i nterface lo0 as alias and it should be permanent

Reply

aix March 29, 2013 at 11:17 PM

This command should work: ifconfig lo0 alias netmas k 255.255.255.255

To make this permanent, I would add this to inittab or to an rc script (/etc/rc.d/rc2.d) so at boot ti me this alias would be

configured.

(I checked around on the net, and I saw netmask 255 .255.255.255 was used many times with lo0, so proba bly there is a reason for this.)

Anonymous March 31, 2013 at 7:08 AM

thanks,

but can u pls tell me how to add this to inittab or to an rc script to make it permanent... ?

or Can't we make this permanent to use the command chdev or through smitty ?

Reply

aix March 31, 2013 at 9:14 AM

I made a typo, correct command should look like: if config lo0 alias ip_address netmask 255.255.255.255

(chdev would be a good solution, just for lo0 devic e it doesn't work)

I think easiest would be in your case to add this c ommand to /etc/rc.net file. You can read more about that:

http://pic.dhe.ibm.com/infocenter/aix/v7r1/index.js p?topic=%2Fcom.ibm.aix.files%2Fdoc%2Faixfiles%2Frc. net.htm

(If you add things to that file, in case you do an OS upgrade, there is a chance you modifications wil l be lost, so document them very

well.)


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AIX for System Administrators_Commands

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