TTL curious

[Hacksawbob]

I have a webserver (esspreso box) which is on the same subnet as the clients that access it. If I ping any other host on the network I get a TTL=128 If I ping this box I get a TTL of 64. Does this mean it is going through a router to get there? I understood that the TTL would decrement each hop, however if I tracert this address it comes back with the one entry as it should for something on the same network. I believe that TTL can be set somewhere, is this set somewhere else, on the router or local machine? i have staff saying it's been flakey lately.

[powdarrmonkey]

I have a webserver (esspreso box) which is on the same subnet as the clients that access it. If I ping any other host on the network I get a TTL=128 If I ping this box I get a TTL of 64. Does this mean it is going through a router to get there?

No, it's just that the default TTL value for reply packets on that box is different to others that you've sampled. Valid values for TTL are 1 through 255.

I believe that TTL can be set somewhere, is this set somewhere else, on the router or local machine?

On a Windows box the echo request packet can be changed (see the documentation, http://www.microsoft.com/resources/d....mspx?mfr=true), but this does not affect the reply packet's TTL. To change that you need to change the default value on the remote box.

i have staff saying it's been flakey lately.

It's not going to be TTL troubles, unless you know that packets are going missing. Since you don't have a router boundary to deal with, your TTLs aren't being decremented anyway, so this is an unrelated problem.

[steve]

As powdarmonkey says, each different OS can use a different TTL:

OS/Device Version Protocol TTL value
AIX 3.2, 4.1 ICMP 255
BSDI BSD/OS 3.1 and 4.0 ICMP 255
Cisco ICMP 254
HP-UX ICMP 255
HP-UX TCP 64
Juniper ICMP 64
Linux 2.0.x kernel ICMP 64
Linux 2.2.14 kernel ICMP 255
Linux 2.4 kernel ICMP 255
Linux Red Hat 9 ICMP and TCP 64
NetBSD ICMP 255
Solaris 2.5.1, 2.6, 2.7, 2.8 ICMP/TCP 255/64
SunOS 5.7 ICMP and TCP 255
Windows for Workgroups TCP and UDP 32
Windows 95 TCP and UDP 32
Windows 98 ICMP/TCP 128
Windows NT 4.0 TCP and UDP 128
Windows Server 2003 128
Windows XP ICMP/TCP/UDP 128

[powdarrmonkey]

As powdarmonkey says, each different OS can use a different TTL:

Note, this table doesn't allow for local sysadmins making changes to the defaults.

[Hacksawbob]

Right OK red hering, looking for my issues elsewhere... apple wireless has had the long bony finger of suspicion pointed at it!