Full Disclosure mailing list archives

Re: abnormal behavior Gmail logon


From: Valdis.Kletnieks () vt edu
Date: Wed, 31 May 2006 06:43:37 -0400

On Wed, 31 May 2006 09:23:08 BST, Edward Pearson said:
This isn't abnormal or weird, It happens when your internet connection
is fairly slow and its because you sometimes receive incomplete headers
for the page (broken or garbled)

If you have noisy hardware that's mangling data in transit, the mangling will
*usually* be detected by the checksums on each IP packet.  The reason your
connection gets slow is because if a corruption is detected, the packet gets
thrown out, and needs to be retransmitted by the sending system.

If you're still on dialup, a noisy phone line will also make things go slower,
as the modem will probably drop back to slower and slower speeds (which are
more noise resistant.  Getting 56K through a 56K modem requires near-perfect
copper - but it will drop back to 44K, 33K, 19.2K. By the time you get down to
9600/4800/1200/300 baud, it can survive incredible amounts of clicks, hums, and
other noises.

Incidentally, the TCP checksums are *not* perfect.  Usually, it doesn't
matter, but you *should* verify the MD5 hash on a large file you've
downloaded (like a .ISO image, etc).  The average .iso is big enough that
you have a fairly good chance of getting an undetected bad packet.

So always check those md5sums.. :)

Attachment: _bin
Description:

_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/

Current thread: