SUMMARY: ftp hash command

From: Ed Strong (
Date: Sat Dec 04 1993 - 01:22:00 CST

I received several comments, some gently requesting that I RTFM which says:

hash Toggle hash-sign (#) printing for each data block

Of course "data block" could be any size. Whereas, the ftp command itself says:

ftp> hash
Hash mark printing on (8192 bytes/hash mark).

The above turns out to be true only when sending.

Here is the most interesting and useful reply:

>From Fri Nov 26 00:50:48 1993
>I think it will turn out that, when receiving, the
>hash mark is printed out for each packet received.
>During an off-net transaction, most systems devolve to
>sending only around 512 bytes per packet. This is an archaic
>assumption, but like SunOS-whois that still points at,
>most tcp/ip implementations still use 512-bytes off-net.
>this IS adjustable, at least in SunOS 4.1.3 and beyond.
>Edit the file /sys/netinet/in_proto.c (as I recall).
>Set tcp_default_mss=1460 for general use.
>BUT, both ends of a transfer must agree to do the right thing.
>Also, you might want to increase the default tcp window sizes
>to something like (32*1460).

I may try this out. Unfortunately there are 10 hops between me and my
destination, so even if we change this at the endpoints the actual packet
size may not increase much. Still, this is worth knowing about.

My thanks to:

Ed Strong

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