Difference between Protocol number and port number

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Configuring ASA to allow ping

Just add ICMP to default inspection class:

ASA(config)#policy-map global_policy

ASA(config-pmap)#class inspection_default

ASA(config-pmap-c)#inspect icmp

Monitoring Internet Connection using IP SLA

Our company may have two connection to the internet through 2 ISPs. If we want to use one connection as primary and other as backup, we can use IP SLA to monitor the link. It detects the link failure even if the connection between modem and ISP fails. So it helps to switch over to the backup path automatically as soon as the primary path is down.

Step1 : Configuring SLA process

R1(config)#ip sla 1

R1(config-ip-sla)#icmp-echo 8.8.8.8

R1(config-ip-sla-echo)#frequency 5 (Means, every 5 second send icmp-echo packet to the ip 8.8.8.8. This can by any reliable IP on internet)

R1(config-ip-sla-echo)#exit

Step2: Scheduling SLA process

R1(config)#ip sla schedule 1 start-time now life forever (Means, start the sla process now and don’t end)

Note: we can check the process using the following command

R1#show ip sla statistics

Step3: Create a track object to track the change. It is used to inform the router about the current condition

R1(config)#track 10 rtr 1 reachability (this will inform the router if any reachability problem occurs. rtr is the old name of IP SLA)

R1(config-track)#exit

Step4: Create two static route two both ISPs with some tweaks

R1(config)#ip route 0.0.0.0 0.0.0.0 fastEthernet 0/0 track 10

R1(config)#ip route 0.0.0.0 0.0.0.0 fastEthernet 0/1 2

Now router will select ISP1 as primary path because of administrative distance is lower. If the link to ISP1 is down, then router automatically switch the connection to ISP2

ASA static/Default Routing configuration

Syntax of static route configuration is :

Route <interface-name> <ip address> <netmask> <gateway ip> [distance]

Objects:

• Configure static routing to inside interface

ASA1(config)#route inside 172.30.10.0 255.255.255.0 172.30.30.2 1
ASA1(config)#route inside 172.30.20.0 255.255.255.0 172.30.30.2 1

• Configure default route to internet

ASA1(config)#route outside 0.0.0.0 0.0.0.0 192.168.1.2

Note: we can use the command “route outside 0 0 192.168.1.2” for default route, both are same.

Usually using Services and Port Numbers

Port	TCP	UDP	Description
20	x		FTP-data
21	x		FTP (login access)
22	x	x	SSH
23	x		Telnet
25	x		SMTP (Mail, MTA)
53	x	x	DNS
80	x	x	HTTP (Web)
110	x	x	POP3(email); generally uses TCP
119	x		NNTP (Usenet news)
139	x	x	NetBIOS (Microsoft)
143	x	x	IMAP (email)
161	x	x	SMTP (Network Monitor)
443	x	x	HTTPS
465	x		SMTPS (Secure mail over SSL)
993	x	x	IMAPS (Secure IMAP over SSL)
995	x	x	POP3S (Secure POP3 over SSL)

Installing GNS3 on CentOS 6.x/RHEL 6.x/Fedora 15

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Configuring router for SDM

SDM configuration steps:

1. Create user accounts
2. Enable http and/or https server
3. Configure http to use local user database

R1(config)#username binoy privilege 15 secret cisco

R1(config)#ip http server

R1(config)#ip http secure-server (allows encrypted access)

R1(config)#ip http authentication local

Now download SDM from www.cisco.com/go/sdm and install it in the computer (requires java runtime environment) and launch the SDM by giving IP address in SDM launcher

Cisco router password recovery process

1. Connect to console port
2. Use the power switch to power cycle the router.
3. Issue the break sequence within 60 seconds of power up to put the router into ROMmon.
4. Type “confreg 0x2142” at the rommon 1> prompt.  (This changes the default configuration register and causes the router to bypass the startup configuration where the forgotten enable password is stored.The configuration register is usually set to 0x2102 or 0x102)
5. Type no after each setup question, or press Ctrl-C to skip the initial setup procedure.
6. Router> enable
7. Router#copy start run
8. Now, change the passwords and give no shutdown commands to interfaces
9. R1(config)# config-register 0x2102 (To make the startup configuration effective while next booting)

Administrative Distance of Routing protocols

Connected interface	0
Static route	1
Enhanced Interior Gateway Routing Protocol (EIGRP) summary route	5
External Border Gateway Protocol (BGP)	20
Internal EIGRP	90
IGRP	100
OSPF	110
Intermediate System-to-Intermediate System (IS-IS)	115
Routing Information Protocol (RIP)	120
Exterior Gateway Protocol (EGP)	140
On Demand Routing (ODR)	160
External EIGRP	170
Internal BGP	200
unknown	255

Installing and configuring SecureCRT for gns3

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