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Wireless Networks Thread, TTL curious in Technical; I have a webserver (esspreso box) which is on the same subnet as the clients that access it. If I ...
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    Hacksawbob's Avatar
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    TTL curious

    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.

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    powdarrmonkey's Avatar
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    Quote Originally Posted by Hacksawbob View Post
    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.

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    steve's Avatar
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    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

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    powdarrmonkey's Avatar
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    Quote Originally Posted by steve View Post
    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.

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



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