cisco – VeriTeknik

SIP NAT on Cisco IOS stop working

ckaraca — Wed, 23 Apr 2014 21:54:41 +0000

Suddenly you realized that external SIP phones stop working without any reason, you should be avare of Cisco routers get stuck sometimes.
There is a trick to solve the issue with two commands, but first of all be sure that the sip is not registered through arterisk cli:

Type on your asterisk:

asterisk -rvvvvv

and check sip peers:

sip show peers

Now you should see the extension as UNKNOWN, if this is the case for you apply these steps on your Cisco IOS:

conf t
no ip nat service sip udp port 5060
exit
clear ip nat translation

To see the results, simply type:

sh ip nat translations

Have fun!

The post SIP NAT on Cisco IOS stop working appeared first on VeriTeknik.

Cisco Router IPv6 Configuration

ckaraca — Mon, 18 Jul 2011 08:33:30 +0000

At the beginning of the year 2011, we decided to apply the IPv6 configuration to our data center (VeriTeknik) and requested our IPv6 block from RIPE. RIRs give out /32 blocks to LIRs at the first assignment. This article describes basic Cisco IPv6 configuration.

The Preparation Steps

Request your IPv6 Addresses from your RIR or LIR
Add IPv6 Route to your AS number in LIR Portal
Get your IPv6 VLAN IP from your Upstream Provider
Configure your router

Configuring Cisco Routers for IPv6

Before you start applying IPv6 on your routers make sure that you backup your current configuration.

First of all, make a table of your arguments such as your IP addresses, AS numbers etc like below, we put some values for you to easily analyze the configuration:

Your AS Number	AS65535
Remote As Number	AS1000
VLAN IP Your Side (Given by Telco op)	2A01:358:4500:2::2/64
VLAN IP remote Side (Telco Side)	2A01:358:4500:2::1
Your IPv6 Addresses to Announce	2B00:7300::/32

Enable IPv6 & IPv6 CEF on your Cisco router:

ipv6 unicast-routing
ipv6 cef
!

Set your IPv6 address to the interface facing telco:

Don’t delete your IPv4 configuration or other necessary codes, just add

interface GigabitEthernet0/0
description $ETH-WAN$
ipv6 address 2A01:358:4500:2::2/64
ipv6 enable
ipv6 virtual-reassembly
..
..
!

Switch to BGP configuration by typing “router bgp 65535”

add:

router bgp 65535
.
.
neighbor 2A01:358:4500:2::1 remote-as 1000
!

type exit and type address-family ipv6 to enter IPv6 configuration

to announce your prefixes type:

address-family ipv6
neighbor 2A01:358:4500:2::1 activate
distance bgp 200 200 200
network 2B00:7300::/32
network 2B00:7300:100::/48
redistribute connected
redistribute static
no synchronization
exit-address-family
!

Type exit one more and you need to add routes for your IPv6 addresses,

ipv6 route 2B00:7300::/32 Null0 254

This is the basic IPv6 configuration for Cisco routers, now you should be able to communicate with IPv6 enabled hosts. To test your configuration you may assign IPv6 to one of your VLANs, an example given below:

interface GigabitEthernet0/1.201
description LOCAL
encapsulation dot1Q 201
.
.
ipv6 address 2B00:7300:100::1/48
!

The post Cisco Router IPv6 Configuration appeared first on VeriTeknik.

Cisco PIX & ASA Host name in greeting fix

ckaraca — Fri, 22 Apr 2011 09:10:35 +0000

If it appears to be all (***) instead of your mail hostname and if you get, “550 Sorry, your HELO/EHLO greeting must resolve (#5.7.1)” error when sending mail to your mail server from outside, run the following command in your CISCO firewall:

no fixup protocol smtp 25

and save with the “wr mem” command

The post Cisco PIX & ASA Host name in greeting fix appeared first on VeriTeknik.