> What is MTU? How do I ping with different sized packets? What would
> that tell me?
> >
MTU is maximum transmission unit (packet size) in bytes that the
interface will transmit/recieve.
If it is linux, run ifconfig and you will see the MTU value listed for
each interface:
eth1 Link encap:Ethernet HWaddr 00:05:5D:6B:D6:BF
inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:4696 errors:0 dropped:0 overruns:0 frame:0
TX packets:3557 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:553921 (540.9 Kb) TX bytes:2482084 (2.3 Mb)
Interrupt:9 Base address:0xd800
Default ethernet MTU is 1500, but sometimes it gets altered along the
way up by the remote end OS or the physical mediums during transmission.
do a man on ping, but on linux it is:
ping -s <packetsize>
tcpdump -vvv host <host>
This will give an output somthing like:
12:59:43.482011 linhost.localdomain > 192.168.0.101: icmp: echo request
(DF) (ttl 64, id 14, len 1328)
12:59:43.482539 192.168.0.101 > linhost.localdomain: icmp: echo reply
(ttl 64, id 3650, len 1328)
where len = packet size. To get this packet size I ran ping -s 1300
192.168.0.101.
This is a pretty informative article:
http://www.erg.abdn.ac.uk/users/gorry/course/inet-pages/mtu.html
There is some information in the iptables man pages - look for clamp or
TCPMSS.
> > Also check to make sure that VNC is actually listening on the port you
> > think it should be. You can netstat -npl to check for that.
>
> I have done netstat and have found out that it is listening on the
> right port (after fixing iptables).
>
> Jeremy
>
> >
>
ta, gb
