Some are having some problems on the ICMP access-list. Try this oneallow pings into the network
access-list 110 permit icmp any any echo
! allow ping responses
access-list 110 permit icmp any any echo-reply
! allow ICMP source-quench
access-list 110 permit icmp any any source-quench
! allow path MTU discovery
access-list 110 permit icmp any any packet-too-big
! allow time-exceeded, which is useful for traceroute
access-list 110 permit icmp any any time-exceeded
! deny all other ICMP packets
access-list 110 deny icmp any any
Sunday, March 30, 2008
Network Tip No. 36: ACL on ICMP
Network Tip No. 35: Stopping the router from crazy output
Stopping the router from crazy output... An annoying problem output everytime you mistype a command and the router thinks you just typed a hostname. For example: The way to handle this is to change the preferred transport method: The output shows the lack of a failed connection based on our mistyped keyword:
Router#shwo
Translating "shwo"...domain server (10.1.1.1)
% Unknown command or computer name, or unable to find computer address
Router#
! Console port
line con 0
transport preferred none
! VTY Ports
line vty 0 5
transport preferred none
Router#shwo
^
% Invalid input detected at '^' marker.
Network Tip No. 34: The reload command
When everything fails.... hehe
Router#reload in 3
Reload scheduled in 3 minutes
Proceed with reload? [confirm]y
Wednesday, March 26, 2008
Linux Tip No. 36: How to Enable IP Forwarding
Enable IP Forwarding
1. Check if IP Forwarding is enabled
Using sysctl:
[root@proxy ~]# sysctl net.ipv4.ip_forward
net.ipv4.ip_forward = 0
or just checking out the value in the /proc system:
[root@proxy ~]# cat /proc/sys/net/ipv4/ip_forward
0Value 0 means it is disabled.
2. Enable IP Forwarding on the fly
[root@proxy ~]#sysctl -w net.ipv4.ip_forward=1or
[root@proxy ~]#echo 1 > /proc/sys/net/ipv4/ip_forward
the setting is changed instantly; the result will not be preserved after rebooting the system.
3. Permanent setting using /etc/sysctl.conf
If we want to make this configuration permanent the best way to do it is using the file /etc/sysctl.conf where we can add a line containing net.ipv4.ip_forward = 1
[root@proxy ~]#vi/etc/sysctl.conf
# Controls IP packet forwarding
net.ipv4.ip_forward = 1
if you already have an entry net.ipv4.ip_forward with the value 0 you can change that 1.
To enable the changes made in sysctl.conf you will need to run the command:
[root@proxy ~]#sysctl -p /etc/sysctl.conf
Restart the network service
[root@proxy ~]#service network restart
Linux Tip No. 35: Enable service at boot up
To Check:
[root@jepoy ~]# chkconfig --list |grep httpd
httpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
To enable at boot up:
[root@jepoy ~]# chkconfig httpd on
Linux Tip No. 34: How to Check Services
This command is used to start/stop your services.
service start/stop/restart/status [root@jepoy ~]# service httpd start
To Stop:
[root@jepoy ~]# service httpd stop
To Restart:
[root@jepoy ~]# service httpd restart
To check:
[root@jepoy ~]# service httpd status
Monday, March 24, 2008
Linux Tip No. 33: How to check your DHCP server
This command tells you what DHCP server you are using.
[root@jepoy ~]# grep dhcp-server-identifier /var/lib/dhcp/dhclient.leases
option dhcp-server-identifier 192.168.0.254;
Linux Tip No. 32: Checking the top 10 directories
Top 10 directories eating up your disk space:
[root@mail etc]# du -cksh * | sort -rn | head -10
852K sysconfig
784K termcap
704K selinux
704K makedev.d
632K firmware
552K X11
544K pam.d
472K prelink.cache
460K alsa
444K postfix
Linux Tip No. 31: Renew/Release DHCP client
[root@proxy ~]# dhclient -r
[root@proxy ~]# dhclient
Internet Systems Consortium DHCP Client V3.0.2
Copyright 2004 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/products/DHCP
The -r flag
explicitly releases the current lease, and once the lease has been released, the client exits.
Sunday, March 23, 2008
Network Tip No. 33: Troubleshootin IGRP
Troubleshooting IGRP Issues
| Router#debug ip igrp events | Shows all IGRP events in real time |
| Router#debug ip igrp transactions | Shows IGRP updates between routers |
Network Tip No. 32: IGRP Routing Optional Commands
Network Tip No. 31: IGRP Routing Commands
IGRP Routing: Mandatory Commands
| Router(config)#router igrp as-number | Enables IGRP routing process. The autonomous system number (AS-number) used in the IGRP routing process must match all other routers that are going to share routing updates in order for communication to take place |
| Router(config-router)#network w.x.y.z | w.x.y.z is the network number of the directly connected network you want to advertise |
Note:
You need to advertise only the classful network number, not a subnet:
Router(config-router)#network 172.17.0.0 not
Router(config-router)#network 172.17.10.0 If you advertise a subnet, you will not receive an error message, because the router will automatically convert the subnet to the classful network address.
Tuesday, March 18, 2008
Linux Tip No. 30: Managing Disk Space
[root@mail ~]# fdisk -l
Disk /dev/sda: 36.4 GB, 36419584000 bytes
255 heads, 63 sectors/track, 4427 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 63 506016 83 Linux
/dev/sda2 64 3905 30860865 83 Linux
/dev/sda3 3906 4427 4192965 82 Linux swap
Disk /dev/sdb: 36.4 GB, 36419584000 bytes
255 heads, 63 sectors/track, 4427 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 * 1 4427 35559846 83 Linux
Linux Tip No. 29: Becoming a Super User
Becoming Super User (The su Command)
[docadmin@mail ~]$ su
Password: ******
[root@mail docadmin]#
When you are prompted, type in the root user's password. The prompt for the regular user ($) will be changed to the super user prompt (#). At this point, you have full permission to run any command and use any file on the system. However, one thing that the su command doesn't do when used this way is read in the root user's environment. As a result, you may type a command that you know is available and get the message "command not found." To fix this problem, you can use the su command with the dash (-) option instead, as follows:
[docadmin@mail ~]$ su -
Password:
[root@mail docadmin]#
When you are prompted, type in the root user's password. The prompt for the regular user ($) will be changed to the super user prompt (#). At this point, you have full permission to run any command and use any file on the system. However, one thing that the su command doesn't do when used this way is read in the root user's environment. As a result, you may type a command that you know is available and get the message "command not found." To fix this problem, you can use the su command with the dash (-) option instead, as follows:
$ su -
Password: ******
#
Linux Tip No. 28: Command-Line Recall
Command-Line Recall
After you type a command line, that entire command line is saved in your shell's history list. The list is stored in a history file, from which any command can be recalled to run again.
[docadmin@mail ~]$ history 20
526 exit
527 su -
528 cd /etc
529 more inittab
530 exit
531 su
532 lspcis
533 lspci
534 su
535 su -
536 su
537 su -
538 su -
539 su -
540 su -
541 id
542 su jepoy
543 history
544 history 10
545 history 20
Network Tip No. 30: RIP Version 2: Optional Commands
RIP Version 2: Optional Commands
|
Network Tip No. 29: RIP Version 2: Mandatory Commands
RIP Version 2: Mandatory Commands
| Router(config)#router rip | Turns on the RIP routing process; the same command as used for RIP Version 1 (RIP-1) |
| Router(config-router)#version 2 | Turns on Version 2 of the routing process. Version 1 is default |
| Router(config-router)#network w.x.y.z | w.x.y.z is the network number of the directly connected classful network you want to advertise |
Network Tip No. 28: Troubleshooting RIP Issues
Network Tip No. 27: RIP Version 2
RIP Version 2
| Router(config-router)#version 2 | RIP will now send and receive RIP-2 packets globally |
| Router(config-if)#ip rip send version 1 | Interface will send only RIP-1 packets |
| Router(config-if)#ip rip send version 2 | Interface will send only RIP-2 packets |
| Router(config-if)#ip rip send version 1 2 | Interface will send both RIP-1 and RIP-2 packets |
| Router(config-if)#ip rip receive version 1 | Interface will receive only RIP-1 packets |
| Router(config-if)#ip rip receive version 2 | Interface will receive only RIP-2 packets |
| Router(config-if)#ip rip receive version 1 2 | Interface will receive both RIP-1 and RIP-2 packets |
Linux Tip No. 27: Exiting the Shell
Linux Tip No. 26: Checking Directories
To find out what your current directory is, type the pwd command:
$ pwd
/usr/bin
To find out the name of your home directory, type the echo command, followed by the $HOME variable:
$ echo $HOME
/home/jepoy
To change your directory, use the cd command. You could also use the tilde (~) character to indicate the home directory. So cd ~ would have the same resultas just cd.
$ cd /var/log
$ pwd
/var/log
To check if its a directory, use the ls -la command. "d" means its a directory.
[jepoy@mail ~]$ ls -al
total 33048
drwx------ 7 jepoy jepoy 4096 Mar 15 12:12 .
drwxr-xr-x 85 root root 4096 Jan 28 13:35 ..
-rw-r--r-- 1 jepoy jepoy 304 Jul 27 2007 .bash_logout
-rw-r--r-- 1 jepoy jepoy 191 Jul 27 2007 .bash_profile
-rw-r--r-- 1 jepoy jepoy 124 Jul 27 2007 .bashrc
drwxr-xr-x 3 jepoy jepoy 4096 Aug 29 2007
dr-x------ 2 jepoy jepoy 4096 Mar 14 15:50 download_only
drwxr-xr-x 2 jepoy jepoy 4096 Aug 16 2007 DVBH
drwxr-xr-x 2 jepoy jepoy 4096 Aug 16 2007 Dynamips
Linux Tip No. 25: Checking Your Login Session
To find out information about your identity, use the id command as follows:
[jepoy@mail docadmin]$ iduid=10023(jepoy) gid=10023(jepoy) groups=10023(jepoy)
Network Tip No. 26: RIP Routing Optional Commands
RIP Routing: Optional Commands
| Router(config)#no router rip | Turns off the RIP routing process |
| Router(config-router)#no network w.x.y.z | Removes network w.x.y.z from the RIP routing process |
| Router(config-router)#passive-interface s0/0 | RIP updates will not be sent out this interface |
| Router(config-router)#neighbor a.b.c.d | Defines a specific neighbor with which to exchange information |
| Router(config-router)#no ip split-horizon | Turns off split horizon (on by default) |
| Router(config-router)#ip split-horizon | Re-enables split horizon |
| Router(config-router#timers basic 30 90 180 270 360 | Changes timers in RIP: |
| 30 = Update timer (in seconds) | |
| 90 = Invalid timer (in seconds) | |
| 180 = Hold-down timer (in seconds) | |
| 270 = Flush timer (in seconds) | |
| 360 = Sleep time (in milliseconds) | |
| Router(config-router)#maximum-paths x | Limits the number of paths for load balancing to x (4 = default, 6 = maximum) |
| Router(config-router)#default-information originate | Generates a default route into RIP |
Thursday, March 13, 2008
Linux Tip No. 24: How to check speed/duplex of your NIC
How to determine the speed/negotiation of your NIC
a. dmesg
[root@mail ~]# dmesg | grep -i duplex
tg3: eth1: Link is up at 100 Mbps, full duplex.
b. ethtool
[root@mail ~]# ethtool eth1
Settings for eth1:
Supported ports: [ MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Advertised auto-negotiation: Yes
Speed: 100Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: g
Wake-on: d
Current message level: 0x000000ff (255)
Link detected: yes
c. mii-tool
[root@mail ~]# mii-tool eth1
eth1: negotiated 100baseTx-FD, link ok
Network Tip No. 25: RIP Routing Commands
RIP Routing Commands
| Router(config)#router rip | Enables RIP as a routing protocol |
| Router(config-router)#network 192.168.10.0 | 192.168.10.0 is the network number of the directly connected network you want to advertise |
Note:
You need to advertise only the classful network number, not a subnet:
Router(config-router)#network 172.17.0.0 not
Router(config-router)#network 172.17.10.0 If you advertise a subnet, you will not receive an error message, because the router will automatically convert the subnet to the classful network address.
Wednesday, March 12, 2008
Network Tip No. 24: IP Classless
IP Classless
| Router(config)#ip classless | Instructs IOS to forward packets destined for an unknown subnet to the best supernet route |
| Router(config)#no ip classless | Turns off the ip classless command |
Linux Tip No. 23: How to check your NIC
How to check your NIC
[root@mail docadmin]# /sbin/lspci |grep -i eth
00:04.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5702X Gigabit Ethernet (rev 02)
02:01.0 Ethernet controller: Intel Corporation 82557/8/9 [Ethernet Pro 100] (rev 08)
Tuesday, March 11, 2008
Thursday, March 6, 2008
Network Tip No. 22: Static Routing-Permanent Option
The permanent Keyword (Optional)
| Router(config)#ip route 172.16.20.0 255.255.255.0 172.16.10.2 permanent | Specifies that the route will not be removed, even if the interface shuts down |
Network Tip No. 21: Static Routing
Static Routing
| Router(config)#ip route 172.16.20.0 255.255.255.0 172.16.10.2 | 172.16.20.0 = destination network |
| 255.255.255.0 = subnet mask | |
| 172.16.10.2 = next-hop address | |
| Read this to say: To get to the destination network of 172.16.20.0, with a subnet mask of 255.255.255.0, send all packets to 172.16.10.2 |
| Router(config)#ip route 172.16.20.0 255.255.255.0 s0/0 | 172.16.20.0 = destination network |
| 255.255.255.0 = subnet mask | |
| s0/0 = exit interface | |
| Read this to say: To get to the destination network of 172.16.20.0, with a subnet mask of 255.255.255.0, send all packets out interface Serial 0/0 |
Network Tip No. 20: Default Routing
Linux Tip No. 22: How to check your sound card
[root@proxy /]# arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: AudioPCI [Ensoniq AudioPCI], device 0: ES1371/1 [ES1371 DAC2/ADC]
Subdevices: 1/1
Subdevice #0: subdevice #0
[root@proxy /]#
Network Tip No. 18: Saving configurations
Wednesday, March 5, 2008
Linux Tip No. 21: How to check your video card
a. Check the graphics card
[root@mail docadmin]# /sbin/lspci |grep -i vga
00:03.0 VGA compatible controller: ATI Technologies Inc Rage XL (rev 27)
b. Check the video card memory size
[root@mail docadmin]# /sbin/lspci -v -s 00:03.0
00:03.0 VGA compatible controller: ATI Technologies Inc Rage XL (rev 27) (prog-if 00 [VGA])
Subsystem: Compaq Computer Corporation: Unknown device 001e
Flags: bus master, stepping, medium devsel, latency 64
Memory at f6000000 (32-bit, non-prefetchable) [size=16M]
I/O ports at 2c00 [size=256]
Memory at f5ff0000 (32-bit, non-prefetchable) [size=4K]
Capabilities: [5c] Power Management version 2
Network Tip No. 17: exec-timeout
exec-timeout Command
| Router(config)#line con 0 | |
| Router(config-line)#exec-timeout 0 0 | Sets time limit when console automatically logs off. Set to 0 0 (minutes seconds) means console never logs off |
| Router(config-line)# |
Tuesday, March 4, 2008
Network Tip No. 16: logging synchronous
Monday, March 3, 2008
Network Tip No. 15: no ip domain-lookup
no ip domain-lookup Command
Router(config)#no ip domain-lookup | Turns off trying to automatically resolve an unrecognized command to a local host name |
Sunday, March 2, 2008
Network Tip No. 14: Assigning a Local Hostname to IP Address
Assigning a Local Host Name to an IP Address
| Router(config)#ip host marbea 192.1.1.1 | Assigns a host name to the IP address. |
| Router#ping marbea | |
| = | |
| Router#ping 192.1.1.1 |
Network Tip No. 13: Creating a Banner
Creating an MOTD Banner
Router(config)#banner motd # This is a secure | # is known as a delimiting character. |
system. Authorized Personnel Only! #Friday, February 29, 2008
Network Tip No. 12: Configuring an Ethernet/Fast Ethernet Interface
Configuring an Ethernet/Fast Ethernet Interface
| Router(config)#int fa0/0 | Moves to Fast Ethernet 0/0 interface mode |
| Router(config-if)#description Sales LAN | Optional descriptor of the link is locally significant |
| Router(config-if)#ip address 192.168.0.1 255.255.255.0 | Assigns address and subnet mask to interface |
Thursday, February 28, 2008
Network Tip No. 11: Configuring a Serial Interface
Configuring a Serial Interface
|
Network Tip No. 10: Moving Between Interfaces
Wednesday, February 27, 2008
Network Tip No. 9: show Commands
show Commands
|
Tuesday, February 26, 2008
Network Tip No. 8: Password Encryption
Password Encryption
Router(config)#service password-encryption
Applies a weak encryption to passwords
Router(config)#enable password cisco
Sets enable password to cisco
Router(config)#line con 0
...
Router(config-line)#password Cisco
Continue setting passwords as above
...
Router(config)#no service password-encryption
Turns off password encryption
Network Tip No. 7: Configuring your Passwords
Configuring Passwords
Works on both routers and switches.
Router(config)#enable password jepoy
Sets enable password
Router(config)#enable secret secret-jepoy
Sets enable secret password
Router(config)#line con 0
Router(config-line)#password console
Router(config-line)#login
Enters console-line mode
Sets console-line mode password to console
Enables password checking at login
Router(config)#line vty 0 4
Router(config-line)#password telnet
Router(config-line)#login
Enters vty line mode for all five vty lines
Sets vty password to telnet
Enables password checking at login
Router(config)#line aux 0
Router(config-line)#password backdoor
Router(config-line)#login
Enters auxiliary line mode
Sets auxiliary line mode password to backdoor
Enables password checking at login
Monday, February 25, 2008
Network Tip No. 6: Configuring a Router Name
Friday, February 22, 2008
Thursday, February 21, 2008
Network Tip No. 4: exit Command
Network Tip No.3: Global Configuration Mode
|
Wednesday, February 20, 2008
Network Tip No.2: Enable Command
enable Command
Router>enable | Moves user from user mode to privileged mode |
Tuesday, February 19, 2008
Linux Tip No. 20: Change your Default Gateway
How to Change Your Default Gateway
Temporary[root@jepoy /]# route add default gw 192.168.1.1 eth0
Permanent
Config file: /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=jepoy
GATEWAY=192.168.1.1
Monday, February 18, 2008
Linux Tip No. 19: View your routing table
[root@proxy ~]# netstat -nr
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
203.189.11.64 0.0.0.0 255.255.255.224 U 0 0 0 eth0
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1
0.0.0.0 203.189.11.65 0.0.0.0 UG 0 0 0 eth0
Sunday, February 17, 2008
Linux Tip No. 18: Restart Network Service
[root@proxy docadmin]# /sbin/service network restart
Shutting down interface eth0: [ OK ]
Shutting down interface eth1: [ OK ]
Shutting down loopback interface: [ OK ]
Disabling IPv4 packet forwarding: net.ipv4.ip_forward = 0
[ OK ]
Bringing up loopback interface: [ OK ]
Bringing up interface eth0: [ OK ]
Bringing up interface eth1: [ OK ]
Thursday, February 14, 2008
Wednesday, February 13, 2008
Linux Tip No. 16 IP Address Aliasing - Permanent
IP Address Aliasing - Permanent
Edit you config file
Config file: /etc/sysconfig/network-scripts/ifcfg-eth0:0
DEVICE=eth0:0
ONBOOT=yes
BOOTPROTO=static
BROADCAST=192.168.10.255
IPADDR=192.168.10.12
NETMASK=255.255.255.0
NETWORK=192.168.10.0
ONBOOT=yes
Tuesday, February 12, 2008
Linux Tip No.15: IP Address Aliasing - Temporary
Network IP aliasing
ifconfig eth0 XXX.XXX.XXX.XXX netmask 255.255.255.0 broadcast XXX.XXX.XXX.255
route add -host XXX.XXX.XXX.XXX dev eth0
ifconfig eth0:0 192.168.10.12 netmask 255.255.255.0 broadcast 192.168.10.255
ifconfig eth0:1 192.168.10.14 netmask 255.255.255.0 broadcast 192.168.10.255
route add -host 192.168.10.12 dev eth0
route add -host 192.168.10.14 dev eth0
Monday, February 11, 2008
Linux Tip No.14: Locally resolve hosts
Locally resolve hosts
File: /etc/hosts
[root@proxy etc]# more hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
203.189.xxx.xxx proxy.jepoy.net
192.168.0.254 proxy
192.168.0.36 winxp
[root@proxy etc]# ping winxp
[root@proxy etc]# ping proxy
64 bytes from proxy (192.168.0.254): icmp_seq=0 ttl=64 time=0.092 ms
Sunday, February 10, 2008
Linux Tip No.13: Setting your resolver
Setting your resolver – DNS Entries
File: /etc/resolv.conf
search name-of-domain.com - Name of your domain or ISP's domain if using their name server
nameserver XXX.XXX.XXX.XXX - IP address of primary name server
nameserver XXX.XXX.XXX.XXX - IP address of secondary name server
Example:
search jepoy.net
nameserver 203.189.xxx.xxx
nameserver 203.189.xxx.xxx
Thursday, February 7, 2008
Linux Tip No. 12: DHCP client configuration
DHCP client configuration/etc/sysconfig/network-scripts/ifcfg-eth0DEVICE=eth0
ONBOOT=yes
BOOTPROTO=dhcp
Tuesday, February 5, 2008
Linux Tip No. 11: Changing your IP Address - Permanent
Changing your IP Address – Permanent
Files: /etc/sysconfig/network-scripts/
[root@proxy network-scripts]# ls -l
total 360
-rw-r--r-- 3 root root 190 Feb 28 2007 ifcfg-eth0
-rw-r--r-- 3 root root 191 Nov 8 2005 ifcfg-eth1
-rw-r--r-- 1 root root 254 Jun 21 2001 ifcfg-lo
DEVICE=eth0/eth1/eth3ONBOOT=yes/noBOOTPROTO=static/none
IPADDR=xxx.xxx.xxx.xxxNETMASK=xxx.xxx.xxx.xxx.GATEWAY=xxx.xxx.xxx Edit ifcfg-eth0:/etc/sysconfig/network-scripts/ifcfg-eth0DEVICE=eth0BOOTPROTO=staticONBOOT=yesIPADDR=10.10.10.10NETMASK=255.255.255.0GATEWAY=10.10.10.1
Monday, February 4, 2008
Linux Tip No. 10: Changing your IP Address - Temporary
Changing your IP Address - Temporary
Syntax:
Ifconfig
[root@bigboy tmp]# ifconfig eth0 10.0.0.1 netmask 255.255.255.0 up The ifconfig command does NOT store this information permanently. Upon reboot this information is lost. (Manually add the commands to the end of the file /etc/rc.d/rc.local to execute them upon boot.)
Thursday, January 31, 2008
Linux Tip No. 9: Setting your hostname
Setting your hostname
File: /etc/sysconfig/network
[root@proxy sysconfig]# more network
NETWORKING=yes
HOSTNAME=localhost.localdomain
Example:
Edit the file
NETWORKING=yes
HOSTNAME=proxy.jepoy.net
[root@proxy docadmin]# /sbin/service network restart
Shutting down interface eth0: [ OK ]
Shutting down interface eth1: [ OK ]
Shutting down loopback interface: [ OK ]
Disabling IPv4 packet forwarding: net.ipv4.ip_forward = 0
[ OK ]
Bringing up loopback interface: [ OK ]
Bringing up interface eth0: [ OK ]
Bringing up interface eth1: [ OK ]
[root@proxy docadmin]# hostname
proxy.jepoy.net
Tuesday, January 15, 2008
Linux Tip No. 8: Tcpdump to capture traffic
Using tcpdump to capture the traffic
[root@proxy /]# /usr/sbin/tcpdump -i eth0 port 80
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
09:17:49.575590 IP proxy.jepoy.ph.56790 > nxdomain.guide.opendns.com.http: S 583111147:583111147(0) win 5840
09:17:49.755526 IP nxdomain.guide.opendns.com.http > proxy.jepoy.ph.56790: S 1378975104:1378975104(0) ack 583111148 win 16384
09:17:49.755592 IP proxy.jepoy.ph.56790 > nxdomain.guide.opendns.com.http: . ack 1 win 1460
09:17:49.756126 IP proxy.jepoy.ph.56790 > nxdomain.guide.opendns.com.http: P 1:248(247) ack 1 win 1460
Monday, January 7, 2008
Linux Tip No. 7: Print System Info
uname - print system info
Example:
[admin@proxy ~]$ uname -a
Linux proxy 2.6.11-1.1369_FC4 #1 Thu Jun 2 22:55:56 EDT 2005 i686 i686 i386 GNU/Linux
Sunday, January 6, 2008
Linux Tip No. 6: Creating a Logical Link
Create a File as a Logical Link to Another File
[root@mail admin]#ln -s existingFile newFile
Example:
Link the maillog to your home directory
[root@mail admin]#ln -fs /var/log/maillog .
[root@mail admin]#ls -al
lrwxrwxrwx 1 root root 16 Jan 7 14:48 maillog -> /var/log/maillog
Wednesday, January 2, 2008
Linux Tip No. 5: Determining the uptime
[root@mail admin]# uptime
10:45:52 up 89 days, 10:26, 1 user, load average: 0.00, 0.02, 0.00
Wednesday, December 26, 2007
Linux Tip No. 4: Sorting the Biggest Directory
This command will show the biggest directory.
[root@nuxmachine admin]# du -Sh | sort -n
4.0K ./backup
9.8M ./backup/web
11G ./backup/home
16K ./.ssh
28K ./backup/Dovecot
28K ./backup/users/last-full
36K .
36K ./backup/users
40K ./backup-sh
328K ./backup/Postfix
628K ./backup/MailScanner
Monday, December 17, 2007
Linux Tip No. 3: How to Check NIC Settings in Tru64
How to Check NIC Speed and Negotiation
#hwmgr get attr -cat network | grep -E "name|speed|duplex"
Thursday, December 13, 2007
Linux Tip No. 2: Combining Tail and Awk
- you can use this command to provide a nice output of logs.
Command:
>tail -f logs.log | grep -e "word" | awk '{ print $12 "\t" $13' }'
"word" - any line containing "word" will be captured
$12 - column 12
"\t" - space
Tuesday, December 11, 2007
How To: Foward Tape Content in Tru64
How To: Forward Tape Content in Tru64
root@machine01:/home/data/backup/databases# mt fsf 1
root@machine01:/home/data/backup/databases# vrestore -t -f /dev/ntape/tape0
vrestore: Date of the vdump save-set: Mon Nov 5 22:22:07 2007
vrestore: Save-set source directory : /home/data/backup/
vrestore: Target directory : /usr1/data/backup/
Tuesday, December 4, 2007
Devices on AIX
Devices on AIX
Devices Information on AIX
1.List all devices on a system
lsdev
Device states are: Undefined; Supported Device, Defined; Not usable
(once seen), Available; Usable
2.List all disk devices on a system (Some other devices are: adapter,
driver, logical volume, processor)
lsdev -Cc disk
3.List all customized (existing) device classes (-P for complete list)
lsdev -C -r class
4.Remove hdisk5
rmdev -dl hdisk5
5.Get device address of hdisk1
getconf DISK DEVNAME hdisk1 or bootinfo -o hdisk1
6.Get the size (in MB) of hdisk1
getconf DISK SIZE hdisk1 or bootinfo -s hdisk1
7.Find the slot of a PCI Ethernet adapter
lsslot -c pci -l ent0
8.Find the (virtual) location of an Ethernet adapter
lscfg -l ent1
9.Find the location codes of all devices in the system
lscfg
10.List all MPIO paths for hdisk0
lspath -l hdisk0
11.Find the WWN of the fcs0 HBA adapter
lscfg -vl fcs0 | grep Network
12.Temporarily change console output to /console.out
swcons /console.out (Use swcons to change back.)
Monday, December 3, 2007
Router: Traffic Shaping
Traffic Shaping
class-map match-any IB-11.70
match access-group name IB-11.70
!
class-map match-any OB-11.70
match access-group name OB-11.70
!
!
policy-map To-Public
class OB-11.70
shape average 256000
!
policy-map To-Lan
class IB-11.70
shape average 256000
!
!
interface FastEthernet0
description ***LAN side***
ip address 20.18.11.65 255.255.255.224
service-policy output To-Lan
speed auto
!
interface Serial0
description *** To Public Serial 2/1 ***
bandwidth 2000000
ip address 20.18.11.98 255.255.255.252
service-policy output To-Public
load-interval 30
clockrate 2000000
!
ip route 0.0.0.0 0.0.0.0 20.18.11.97
!
!
ip access-list extended IB-11.70
permit ip any host 20.18.11.70
ip access-list extended OB-11.70
permit ip host 20.18.11.70 any
Note:
The service is always in the OUTPUT policy.
Service Policy To-LAN is inbound of LAN.
Service Pplicy To-Public is outbound of LAN.
Linux Tip No. 1: Change Timezone
Change Timezone on AIX
chtz (timezone eg GMT0BST) - Changes the timezone in /etc/environment file
Thursday, November 29, 2007
Router: NAT with DHCP
ip dhcp excluded-address 192.168.0.1 192.168.0.127
!
ip dhcp pool LANDHCP
network 192.168.0.0 255.255.255.0
domain-name jefferson.com
dns-server 20.18.11.34
netbios-name-server 20.18.11.34
default-router 192.168.0.1
!
interface Ethernet0/0
description **** To Public Interace Fa0/1 ****
ip address 20.18.10.2 255.255.255.252
ip nat outside
ip virtual-reassembly
full-duplex
!
interface Ethernet1/0
description ***Connection To LAN ***
ip address 192.168.0.1 255.255.255.0 secondary
ip address 20.18.10.129 255.255.255.128
ip nat inside
ip virtual-reassembly
full-duplex
ip route 0.0.0.0 0.0.0.0 20.18.10.1
!
ip nat inside source list 10 interface Ethernet0/0 overload
!
access-list 10 permit 192.168.0.0 0.0.0.255
access-list 10 deny any
Wednesday, November 28, 2007
Router: NAT with Secondary IP Address
interface Ethernet0/0
description **** To Public Address ****
ip address 20.18.10.2 255.255.255.252
ip nat outside
ip virtual-reassembly
full-duplex
!
interface Ethernet1/0
description ***Connection To LAN ***
ip address 192.168.0.1 255.255.255.0 secondary
ip address 20.18.10.129 255.255.255.128
ip nat inside
ip virtual-reassembly
full-duplex
ip route 0.0.0.0 0.0.0.0 20.18.10.1
!
ip nat inside source list 10 interface Ethernet0/0 overload
!
access-list 10 permit 192.168.0.0 0.0.0.255
access-list 10 deny any
Monday, November 19, 2007
Tape Commands in AIX
Useful Tape commands in AIX
1.Rewind and eject the rmt0 tape drive
# tctl -f /dev/rmt0 offline
2.Rewind the rmt0 tape drive
# mt -f /dev/rmt0 rewind
3.Check the content of the tape
#tctl -f /dev/rmt0.1 -b 1024 -n read
Tape Commands in Tru64
*****************************
Useful Tape Commands in Tru64
*****************************
Rewind and unload the tape
mt -t /dev/ntape/tape0 offline
1. rewind the tape
#mt -f /dev/ntape/tape0 rewind
or
#mt rewind
2. check the content
#vrestore -t -f /de/ntape/tape0
3. for interactive resotre
#vrestore -i
add - add the file
restore -restore the file
4. for manual restore
Example: restore jeff02.backup.log file from tape /dev/ntape/tape0/jeff02 to the current directory
# vrestore -x /jeff02/jeff02.backup.log
#vrestore -x -D /tmp /jeff02/jeff02.backup.log
root@jeff02:/tmp# cd /home
root@jeff02:/home# vrestore -x -D /tmp /jeff02/jeff02.backup.log
vrestore: Date of the vdump save-set: Mon Oct 22 20:33:06 2007
vrestore: Save-set source directory : /
vrestore: Target directory : /tmp
Monday, November 5, 2007
AIX as NTP Client
AIX as NTP Client
On machine that will be the client:
1. In file /etc/ntp.conf
Add:
server
driftfile /etc/ntp.drift
tracefile /etc/ntp.trace
2. Issue command:
ntpdate
NOTE:If it doesn't say "No server suitable for synchronization found" proceed
to next step.
3. Start using:
#smitty xntpd -> Start at both system restart and now
or
#startsrc -s xntpd
and uncomment the line in /etc/rc.tcpip
start /usr/sbin/xntpd -x "$src_running"
Let the daemon run for 6 miuntes before proceeding to the next step - or
may get stratum 16 error.
4.
#lssrc -ls xntpd
Stratum should show between 3-4, but longer is okay so long as not 16.
#ntpdate -d (to sync server to client)
# ntpq -p
remote refid st t when poll reach delay offset jitter
=====================================================================
LOCAL(0) LOCAL(0) 3 l 9 64 377 0.000 0.000 0.000
*swisstime.ethz. .DCFa. 1 u 17 64 377 25.088 -10.040 1.071
Thursday, October 25, 2007
NTP on UNIXTru64
NTP Information
NTP Version
1-ntpd daemon
2-xntpd
3-xntpd
SYSMAN
# /usr/bin/sysman ntp_config
# ntpq -p
remote refid st t when poll reach delay offset jitter
=====================================================================
LOCAL(0) LOCAL(0) 3 l 9 64 377 0.000 0.000 0.000
*xyzabc.ethz. .DCFa. 1 u 17 64 377 25.088 -10.040 1.071
% xntpdc -p
remote refid st when poll reach delay offset disp
==========================================================================
*hosta.corp.com hostj.corp.co 2 47 64 377 31.3 93.94 16.5
+hostb.corp.com hoste.corp.com 3 212 1024 377 33.8 89.58 16.9
.hostc.corp.com hostf.phi.edu 2 111 1024 377 39.1 46.98 17.7
Edit the configuration file /etc/ntp.conf
server 127.127.1.0 # local clock
server 129.132.2.21 # swisstime.ethz.ch (stratum 1)
driftfile /etc/ntp/drift
multicastclient # listen on default 224.0.1.1
broadcastdelay 0.008
Start NTP Server and check /var/log/messages
# /etc/rc.d/init.d/ntpd start
You can use sysman to configure NTP client.
Edit /etc/ntp.conf and add:
server
server
server
In /etc/rc.config set:
XNTPD_CONF="YES"
XNTP_SERV1="ntp_server1"
export XNTP_SERV1
XNTP_SERV2="ntp_server2"
export XNTP_SERV2
XNTP_SERV3="ntp_server3"
export XNTP_SERV3
# ntpdc monlist
to get the lis
#ntpdate -b
How To: AIX Networking
Network Administration on AIX
1.TCP/IP related daemon startup script
/etc/rc.tcpip
2.To view the route table
netstat -r
3.To view the route table from the ODM DB
lsattr -EHl inet0 -a route
4.Temporarily add a default route
route add default 192.168.1.1
5.Temporarily add an address to an interface
ifconfig en0 192.168.1.2 netmask 255.255.255.0
6.Temporarily add an alias to an interface
ifconfig en0 192.168.1.3 netmask 255.255.255.0 alias
7.To permanently add an IP address to the en1 interface
chdev -l en1 -a netaddr=192.168.1.1 -a netmask=0xffffff00
8.Permanently add an alias to an interface
chdev -l en0 -a alias4=192.168.1.3,255.255.255.0
9.Remove a permanently added alias from an interface
chdev -l en0 -a delalias4=192.168.1.3,255.255.255.0
10.List ODM (next boot) IP conguration for interface
lsattr -El en0
11.Permanently set the hostname
chdev -l inet0 -a hostname=www.tablesace.net
12.Turn on routing by putting this in rc.net
no -o ipforwarding=1
13.List networking devices
lsdev -Cc tcpip
14.List Network Interfaces
lsdev -Cc if
15.List attributes of inet0
lsattr -Ehl inet0
16.List (physical layer) attributes of ent0
lsattr -El ent0
17.List (networking layer) attributes of en0
lsattr -El en0
18.Speed is found through the entX device
lsattr -El ent0 -a media speed
19.Set the ent0 link to Gig full duplex
(Auto Negotiation is another option)
chdev -l ent0 -a media speed=1000 Full Duplex -P
20.Turn off Interface Specic Network Options
no -p -o use isno=0
21.Get (long) statistics for the ent0 device (no -d is shorter)
entstat -d ent0javascript:void(0)
Save Now
22.List all open, and in use TCP and UDP ports
netstat -anf inet
23.List all LISTENing TCP ports
netstat -na | grep LISTEN
Timezone on Tru64
Change Timezone on Unix Tru64
/etc/zoneinfo
/etc/zoneinfo/localtime
/etc/zoneinfo/sources
zic(8)
Changing localtime to New York
# ln -sf /etc/zoneinfo/America/New_York /etc/zoneinfo/localtime
# ln -sf /etc/zoneinfo/Hongkong /etc/zoneinfo/localtime
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