Revision as of 06:43, 20 May 2009

IOS and Linux Goodies

This page is part of the Netband Project

IOS Goodies

• send messages to other adminsitrative users through the cli

B1rt1#send *
Enter message, end with CTRL/Z; abort with CTRL/C:
hej hej
^Z
Send message? [confirm]
B1rt1#
***
***
*** Message from tty194 to all terminals:
***
hej hej

B1rt1#
***
***
*** Message from tty194 to all terminals:
***
hej hej

• disable password check on telnet sessions

line vty 0 4
 no login
line vty 5 15
 no login

• log straight into privilege mode

aaa new-model
username admin privilige 15 password cisco 
!
aaa authentication login default group local
aaa authorization console
aaa authorization exec default local

• tells the router to hold messages until it detects no input from the keyboard and no other output from the router.

line con 0
 logging synchronous
line aux 0
line vty 0 4
 logging synchronous
line vty 5
 logging synchronous

• Show the configuration from a user specified point

Switch#sh run | begin router ospf
router ospf 1
 router-id 192.168.1.2
 log-adjacency-changes
 passive-interface FastEthernet0/5
 network 192.168.1.2 0.0.0.0 area 0
 network 192.168.1.6 0.0.0.0 area 0

• Or type / at --more-- and the string you are searching for

Switch#sh run
Building configuration...
<output omitted>
/router ospf
filtering...
router ospf 1
 router-id 192.168.1.2
 log-adjacency-changes
 passive-interface FastEthernet0/5
 network 192.168.1.2 0.0.0.0 area 0
 network 192.168.1.6 0.0.0.0 area 0

Linux Godies

• When you look at logs and need realtime monitoring use the -f argument on tail. If you've changed something in the MRTG config file and want to know if it is correct use "tail -f /var/log/mrtg/mrtg.log" to monitor the log.

root@UbuntuBox:~# tail -f /var/log/mrtg/mrtg.log
2009-04-20 08:30:05: ERROR: Target[Router][_IN_] 'Di $target->[14]{$mode} ' (kill): Can't call method "Di" on unblessed reference at (eval 42) line 1.
2009-04-20 08:30:05: ERROR: Target[Router][_OUT_] 'Di $target->[14]{$mode} ' (kill): Can't call method "Di" on unblessed reference at (eval 43) line 1.
2009-04-20 08:35:03: ERROR: Target[Router][_IN_] 'Di $target->[14]{$mode} ' (kill): Can't call method "Di" on unblessed reference at (eval 42) line 1.
2009-04-20 08:35:03: ERROR: Target[Router][_OUT_] 'Di $target->[14]{$mode} ' (kill): Can't call method "Di" on unblessed reference at (eval 43) line 1.

• Linux network emulater
• Can be used to emulate slow wan links with packet drops, delay and jitter

http://www.linuxfoundation.org/en/Net:Netem

• Network Connection Bridge
• This can be used to bridge two ethernet connections under ubuntu

https://help.ubuntu.com/community/NetworkConnectionBridge