Archive for the 'cisco' Category

Access to real Cisco routers and switches for free

Preparing for Cisco certification exam and need real equipment required to accomplish all those CCNA or CCNP labs? That’s not a problem any more. This is due to availability of Packet Tracer for Linux and Community Lab hosted by people behind packetlife.net. As for Packet Tracer it supports Linux natively now — Cisco offers it as deb package for Ubuntu or Debian and there is no need to use Wine to get Packet Tracer working in Linux. Try searching the web for “packet tracer deb” and I am sure you’ll find where to download desired file shortly (we do not share pirated content here).

Anyways sometimes Packet Tracer as like as dynamips/gns3 are not a panacea when it’s necessary to emulate mid-sized network or test some specific ios features on real Cisco devices. There are several options: the first and the easiest one means to buy Cisco device. But we all know that Cisco’s pricing policy is far away from democratic in application to individual users so even used or refurbished Cisco router/switch will cost enough to think about another option. Second option is to schedule access to Community Lab at packetlife.net. Nice to know the access to it is absolutely free so anyone can get logon to Cisco routers, switches or ASAs once user reached his/her timeslot. Here is the list of hardware you can have access to (there are multiple devices of the same model):

Cisco ASA 5505
Cisco 2811 (2xWIC-2T)
Cisco 1841 (1xWIC-2T)
Cisco Catalyst 3550-24

Not bad for free lab as for me. The lab is broken into two blocks so user can reserve only one block or both blocks simultaneously. This is to make it possible to access the lab by multiple users simultaneously. Devices are connected to each other according to predefined topology — see separate diagrams for Ethernet and Serial connections below (they are split to prevent overhead on the graph I guess). All documentation as well as FAQs can be found here: here and here. Thanks to Jeremy Stretch.

packetlife community lab ethernet topology

 

packetlife community lab serial topology

P.S. By the way if you can share any other similar labs allowing people on the web to access Cisco (or some other networking devices) — you are welcome to share this information here. Thanks!

Cisco GRE example setup

Hosts from LAN1 should be able to access hosts at LAN2 and vice-versa through GRE tunnel between R1 and R2. ISP doesn’t care what networks are behind R1 and R2 so the only way to establish connection between LAN1 and LAN2 is to use VPN, in this example we use GRE.


GRE setup example topology

Continue reading…

15+ “must have” Cisco Cheat Sheets

cheat sheetBelow is the link list to essential Cisco related cheat sheets (collection of notes or quick reference guides whatever). By the way, we don’t recommend to cheat anything and/or do a cheating of any sort by means of using these materials ;)

1. Cisco IOS Versions what’s this?)
2. Physical Terminations/Connectors (what’s this?)
3. VLANs (what’s this?)
4. Quality of Service (what’s this?)
mpls cheat sheet small 5. MPLS (what’s this?)
6. IP Access Lists what’s this?)
7. Spanning Tree (what’s this?)
8. OSPF (what’s this?)
9. EIGRP (what’s this?)
10. BGP (what’s this?)

11. General Cisco IOS cheat sheet (router/switch commands etc.)
12. Cisco Commands for Beginners
13. Descriptive list of Cisco Commands (fresh)
14. Cisco IOS Firewall Cheat Sheet (Official Design Guide)
15. Cisco – Ethernet Encapsulation (in pdf)
16. Mini CCNA Cheat Sheet
17. CCNA Cheat Sheet (commands debugging)
18. Connector Pinouts Cheat Sheets

Great thanks to Jeremy Stretch (author of packetlife.net) for the first 10 cheat sheets from above list (to get them all just download this package).

Dump ipcad output into sqlite3

sqliteipcad is IP accounting daemon with Cisco-like ip accounting export. It runs in background, listens traffic on the specified interfaces, and records the traffic for later retrieval and analysis.

Here is a piece of shell code that allows to export ipcad output into sqlite3 database format:

echo "create table traffic (src, dst, pkt, bt);" | sqlite3 /tmp/throttle.db
rsh 127.0.0.1 show ip accounting | grep "^ " | grep -vi source | awk \
'{print"insert into traffic values (\""$1"\",\""$2"\",\""$3"\",\""$4"\");"}' \
| sqlite3 /tmp/throttle.db

To make this working ipcad should be configured not to capture ports and to enable rsh service. In my case ipcad has the following settings set in ipcad.conf:

capture-ports disable;
interface eth0;
rsh enable at 127.0.0.1;
rsh 127.0.0.1 admin;
rsh ttl = 3;
rsh timeout = 30;
pidfile = /var/run/ipcad.pid;
memory_limit = 100m;

and output (rsh 127.0.0.1 show ip accouting) is like:

192.168.0.7      192.168.0.1                 113241           166387462
192.168.0.1      192.168.0.7                  72117             4282846
192.168.0.77     66.235.184.245                2448              821095
66.235.184.245   192.168.0.77                  3995              697371

The main problem is that it sqlite3 is rather slow and it takes eleven (11!!!) seconds to export 1000 entries of ipcad’s output into database. This was got at PC with 1.4Ghz CPU and 512Mb RAM.

If anybody knows how to get it faster, PLEASE LET ME KNOW! Thanks.

Information Improvisation: Traffic Engineering Server is new Solution for Bandwidth Management and QoS. It’s especially suitable for Broadband ISPs and SMEs.




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My name is Artem N. (artiomix AT gmail DOT com) and I'm Linux/Unix, Cisco systems engineer. The main idea of Linux Screw is to share relevant knowledge, skills and observations over The Web. Here you can find a lot of information related to different Linux distributions, FreeBSD, IOS as well as a other Open Source around staff. Read more ››