Networking Headache Solved !

ext3 resize

brianchrist — Mon, 04 May 2009 11:12:03 +0000

after struggling on how to resize ext3 partition, finally the answer is so beautifully prepared by opensuse team:

use yast partition )

it works very charm….

Mikrotik & Catalyst

brianchrist — Mon, 12 Nov 2007 13:30:36 +0000

Sometimes I found that network connection between Mikrotik and Catalyst doesn’t seem to work smooth.

Problem:
Ping timeouts, bad connectivity, data loss

Check:
Show status on catalyst’s port connected to the mikrotik interface. You’ll find some errors and CRCs.

Workaround:
Set the catalyst port to autospeed and auto duplex, set the mikrotik interface to fix 100mbps, full duplex.
If that not solve, try vice versa or other combinations.
Most of the time solve the problem.

Postfix: Temporary failure

brianchrist — Sat, 10 Nov 2007 23:02:00 +0000

After a system crash (caused by overloaded on Power Source) my Postfix is not working properly, symptoms:

- sent and receive (SMTP & POP) work normal, no error
- no mail received
- in mail log there is “temporary failure” words

Workaround:

- look at the log detail
- this error is not caused by postfix software, but by it’s supported softwares
- make sure mysql (database), amavis (antivirus), spamassassin (spam blocker) are running

Here’s an example of failed amavis:

Nov 10 09:08:11 smtp3 postfix/smtpd[10079]: warning: 202.57.4.66: address not listed for hostname mail.id.dbsvickers.com
Nov 10 09:08:11 smtp3 postfix/smtpd[10079]: connect from unknown[202.57.4.66]
Nov 10 09:08:11 smtp3 postfix/smtpd[10079]: E313914D7E8: client=unknown[202.57.4.66]
Nov 10 09:08:11 smtp3 postfix/cleanup[8259]: E313914D7E8: message-id=<2PwwjhNaX0000a226@dbsvi-es01.id.dbsvickers.com>
Nov 10 09:08:11 smtp3 postfix/qmgr[4947]: E313914D7E8: from=<>, size=2799, nrcpt=1 (queue active)
Nov 10 09:08:11 smtp3 amavis(client)[10140]: failed to connect(): Connection refused
Nov 10 09:08:11 smtp3 amavis(client)[10140]: failing with EX_TEMPFAIL: Connection refused
Nov 10 09:08:11 smtp3 postfix/smtpd[10079]: disconnect from unknown[202.57.4.66]
Nov 10 09:08:11 smtp3 postfix/pipe[10071]: E313914D7E8: to=, relay=vscan, delay=0, status=deferred (temporary failure
)

Mikrotik Hang Randomly

brianchrist — Thu, 08 Nov 2007 16:47:36 +0000

Problem:
Mikrotik hang pada waktu yg random, ciri2 nya kalau dilewatkan traffic agak besar.

Check:
Check penggunaan IRQ oleh peripheral di PC, apakah ada 1 IRQ yg dipakai sharing untuk beberapa device terutama device network.

Workaround:
Kalau bisa di set manual IRQ untuk setiap network device, lalu reserve IRQ yg digunakan di BIOS supaya tidak di assign ke device lain. Kalau tidak bisa manual, disable modul-modul yg menggunakan IRQ yang ada di mainboard: serial, parallel,video dll supaya bisa digunakan untuk keperluan network card.

Tunnel problem

brianchrist — Thu, 08 Nov 2007 15:32:20 +0000

Problem:
dari Bandung laporan ga bisa buka www.microsoft.com dan www.mcafee.com, padahal dicoba dari Jakarta baik-baik aja. Website lain juga bisa dibuka normal.

Check:
Hasil analisa traffic, request HTTP pertama berhasil dikirim dan dapet reply, berarti point-to-point network OK, selanjutnya request kedua dikirim tapi tidak ada jawaban.

Workaround:
Network Bandung menggunakan tunnel antara cisco dan mikrotik (IPIP) dengan MTU 1480. Jadi kemungkinan website microsoft, mcafee dan teman2nya tidak memperbolehkan paket TCP yg terpisah (Fragmented). Normalnya MTU untuk ethernet itu 1500, tunnel IPIP mikrotik 1480, dengan perkiraan ukuran header sekitar 50 maka MTU di client harus diubah ke 1430. Setiap paket yg keluar dari router diubah MSS-nya (maximum ukuran paket) jadi lebih kecil supaya tidak terjadi fragment. Untuk amannya coba aja dijadikan 1400. Solved!