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Showing posts from November 4, 2007

SolarWinds Named to Software Magazine’s 25th Annual Software 500

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SolarWinds Named to Software Magazine’s 25th Annual Software 500Software Magazine Ranks SolarWinds as one of the World’s Largest Software CompaniesAustin, TX — Oct. 16, 2007 — SolarWinds today announced its inclusion on the Software Magazine’s Software 500 ranking of the world’s largest software and service providers, now in its 25th year. SolarWinds was ranked 276th, with software revenue of $37.9 million.

“The 2007 Software 500 results show that growth in the software and services industry was healthy from 2006 to 2007, the ranking year. The industry continues to be dynamic with more than 98 new companies on the list this year for the first time,” says John P. Desmond, editor of Software Magazine and Softwaremag.com. “The top four business sectors this year are System Integration Services/IT Consulting, Application Development, Financial Applications and Security Tools/Systems. It may be the case that the difficulty companies have in developing and keeping their own IT skilled worker…

Understanding and Configuring PPP CHAP Authentication

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Introduction
The Challenge Handshake Authentication Protocol (CHAP) (defined in RFC 1994 ) verifies the identity of the peer by means of a three-way handshake. These are the general steps performed in CHAP:

After the LCP (Link Control Protocol) phase is complete, and CHAP is negotiated between both devices, the authenticator sends a challenge message to the peer.

The peer responds with a value calculated through a one-way hash function (Message Digest 5 (MD5)).

The authenticator checks the response against its own calculation of the expected hash value. If the values match, the authentication is successful. Otherwise, the connection is terminated.

This authentication method depends on a "secret" known only to the authenticator and the peer. The secret is not sent over the link. Although the authentication is only one-way, you can negotiate CHAP in both directions, with the help of the same secret set for mutual authentication.

For more information on the advantages and disadvanta…

【遊記】2007年10月新加坡出差

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今晚因為咳嗽嚴重終於被我同事拖去看了醫生,吃了藥之後看來是沒法再撐過午夜就要見周公,所以趁著睡前最後一段時間把我上個月到新加坡出差當學生的照片分享出來,也許對還沒有去過新加坡的人有用處,日後有空再加上個人經歷及美食感想!



新加坡美食及夜景探索之第一日



新加坡美食及夜景探索之第二日



新加坡美食及夜景探索之第三日



新加坡美食及夜景探索之第四日



新加坡美食及夜景探索之第五日



新加坡美食及夜景探索之第六日

Configuring Lock-and-Key Security (Dynamic Access Lists)

Benefits of Lock-and-Key
Lock-and-key provides the same benefits as standard and static extended access lists (these benefits are discussed in the chapter "Access Control Lists: Overview and Guidelines"). However, lock-and-key also has the following security benefits over standard and static extended access lists:
Lock-and-key uses a challenge mechanism to authenticate individual users.Lock-and-key provides simpler management in large internetworks.In many cases, lock-and-key reduces the amount of router processing required for access lists.Lock-and-key reduces the opportunity for network break-ins by network hackers.
With lock-and-key, you can specify which users are permitted access to which source and destination hosts. These users must pass a user authentication process before they are permitted access to their designated hosts. Lock-and-key creates dynamic user access through a firewall, without compromising other configured security restrictions.

When to Use Lock-and-Key
T…

IP Access List Entry Sequence Numbering

Benefits
The ability to apply sequence numbers to IP access list entries simplifies access list changes. Prior to the IP Access List Entry Sequence Numbering feature, there was no way to specify the position of an entry within an access list. If a user wanted to insert an entry (statement) in the middle of an existing list, all of the entries after the desired position had to be removed, then the new entry was added, and then all the removed entries had to be reentered. This method was cumbersome and error prone.

This feature allows users to add sequence numbers to access list entries and resequence them. When a user adds a new entry, the user chooses the sequence number so that it is in a desired position in the access list. If necessary, entries currently in the access list can be resequenced to create room to insert the new entry.

Sequence Numbering Behavior




For backward compatibility with previous releases, if entries with no sequence numbers are applied, the first entry is assigned a…

阿里巴巴香港掛牌~開盤漲2倍 超額認購258倍

大陸最大電子商務網站阿里巴巴(1688),今天(6)在香港掛牌上市,估計最高募集金額將超過台幣2860億,不僅可望成為港股港股有史以來募集資金最高的網路股,也是繼網路搜尋龍頭Google2004年上市之後,最受矚目的網路企業上市案。

創下港交所有史以來,唯一一家在星期二掛牌上市的公司,就是他,全大陸最大的入口網站阿里巴巴,上市第一天氣勢不同凡響,開盤價達到每股126元台幣,比起發行價56.7元,漲幅超過二倍,一躍登上香港科技股龍頭寶座。

馬雲表示,今天很滿意阿里巴巴的股價表現,他說,從今早股價表現可以看出,當初招股的定價是合理的,他也希望可與股東、員工共同創造更多的財富。

挾著大陸第一互聯網,以及台灣首富郭台銘也投資的光環,阿里巴巴首度公開招股表現不俗,光是香港部分,就超額認購258倍,凍結資金更創下1兆8900億台幣,刷新中國互聯網企業,境外公開發售融資紀錄。

投資人瘋狂捧場,總市值達到2864億台幣,阿里巴巴上市後,集資金額更可望超過google,成為全球最大規模,首度公開釋股案,集結全球的資本目光阿里巴巴上市招股,讓7年前風靡一時的科網股狂潮,再度席捲香港!

MTU(Maximum Transmission Unit) is not factored into the EIGRP metric calculation

自從我成為Cisco講師以來,一直有一個無解的問題在我腦海中,那就是EIGRP Metric的計算公式與課本中所提到相關EIGRP會考慮到的相關參數一直無法搭配上去。

課本教材裏(不論是ICND 2.3 or BSCI 3.0)都提到了EIGRP Metric有五個參數(Bandwidth, Delay, Reliability, Load, MTU),其中預設會使用的參數是Bandwidth & Delay(因為在EIGRP Metric計算公式中預設K1=K3=1,K2=K4=K5=0),因此其他的參數在預設情況之下並不會納入考量。

以下就是EIGRP的Metric計算公式:

metric = [K1 * bandwidth + (K2 * bandwidth) / (256 - load) + K3 * delay] * [K5 / (reliability + K4)]

因此問題就浮現了…在這個公式運算中根本沒有看到MTU這個參數的存在,但是翻遍Cisco Documents & Course Material就是找不到任何一段正式的說明直接表示MTU雖然屬於EIGRP Metric交換的一部份但是在EIGRP Metric的計算過程中並未加入計算。

今晚我在準備新版ICND2 1.0的教材時,終於看到了一段話:

"Note: Although MTU is exchanged in EIGRP packets between neighbor routers, MTU is not factored into the EIGRP metric calcaulation."

除此之外,我覺得CCNA這次的大改版其實在內容上相較於CCNP 3.0改版來說在內容是比較紮實的...尤其是ICND1,所談論的領域大幅地增加(有好也有壞,因為談得愈多就愈不深入…),不過在許多文字敘述上及觀點的糾正有很多改進(如: show vtp status中VTP Version常常讓人誤解的意思/VTP Domain Name會自動學習的特色/設備之間改口建議使用FIX手動設定SPEED/Duplex的註解..)都有助於導正學生因為文字上的說明不清而誤解意義。

PS:EIGRP計算metric中的Delay,所使用的單位比較特別,是將milisecond(…