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Basic Cisco IOS Commands

Most of the time I use Mikrotik routers running RouterOS, and occasionally I have to use Cisco IOS. But when it comes to this I have forgotten the basic commands. This time I’m going to put some here so I can refer back to.

1. Change between normal config booting (0×2102) to ignoring the¬†NVRAM config (0×2142)

Router>en
Router#conf t
Router(config)#config-register 0x2142
Router(config)#end
Router#copy running-config startup-config
Router#reload

2. Add an IP address to a interface (e0/0)

Router>en
Router#conf t
Router(config)#int e0/0
Router(config-if)#ip addr 10.8.0.8 255.255.0.0
Router(config-if)#no sh
Router(config-if)#end

3. Enable Telnet

Router>en
Router#conf t
Router(config)#line console 0
Router(config-line)#password mycoolpassword
Router(config-line)#login
Router(config-line)#end
Router#conf t
Router(config)#line vty 0 4
Router(config-line)#password mycoolpassword
Router(config-line)#login
Router(config-line)#end

4. Write config to NVRAM

Router>en
Router#copy running-config startup-config
Router#reload

I will add more over time. If you have any you think should be on here, leave a comment below.

Wireshark on a remote Linux host using SSH

First you need tshark installed on the remote linux host: sudo yum install tshark -y or sudo apt-get install tshark -y. On the local linux machine you need the normal wireshark packages.

Then from your local linux machine you can run:

[user@linux ~]# wireshark -k -i <(ssh -l root REMOTEHOST tshark -w - not tcp port 22)

Where REMOTEHOST is the remote linux host. The Wireshark GUI should open on your computer and you will see the flow of packets come in.

Don’t log SNMP info messages on CentOS

If you run something like Observium which polls SNMP on your hosts every five minutes, you will get a lot of Connection from UDP: messages in your log files. This can be bad if you send these logs to a syslog server.

On CentOS you can change the verbosity that SNMPD logs at.

Edit this line in your etc/init.d/snmpd file.

OPTIONS="-LS0-5d -Lf /dev/null -p /var/run/snmpd.pid"

Then just restart SNMPD

[user@linux ~]# sudo service snmpd restart

First impressions of VoIP on 4G

4G (LTE) has been available for a couple of months now in cities around the UK. If you are in Birmingham, London, Bristol, Leeds or Manchester you are likely to be in a 4G serviced area, and surprisingly these cities have very good coverage when you’re in one. EE claim that it will have 98% coverage by the end of 2014.

At the time of writing, the only provider of 4G in the UK is EE – Everything Everywhere. Unlike other mobile providers, EE actually allow the use of VoIP on their data network.

Read the rest over at sipcentric.com