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On 25 Jun 2009, at 08:10, Adam Carter wrote: |
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>>> I've got one machine here on the LAN which isn't responding to |
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>>> broadcast |
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>>> ping. Any idea why not? |
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>> |
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>> You need to set icmp_echo_ignore_broadcasts to 0. Default is |
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>> 1, mainly for dos prevention: |
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>> |
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>> # sysctl net.ipv4.icmp_echo_ignore_broadcasts=0 |
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> |
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> I thought it would default to off in most OSes these days, because of; |
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> http://en.wikipedia.org/wiki/Smurf_attack |
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> |
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> Are those other machines patched up? |
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They're all on the LAN, anyway, but: |
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192.168.1.71 - the machine from which the ping was sent (don't know if |
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that makes a difference). Mac OS X 10.5, fairly recent updates, but |
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perhaps not this month's. |
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192.168.1.43 - Gentoo 1.4 profile, 2.4 kernel, not updated in at least |
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3 years, well due for retirement, just as soon as I've moved services |
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to 192.168.1.100 |
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192.168.1.22 - network KVM [1], probably can't get a firmware update, |
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unfortunately. :( Not a very recent one, anyway. Although they may |
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still sell it, I'm pretty sure it's rebadged OEM & development on the |
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product is ceased. |
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192.168.1.9 - LaserJet 4000, JetDirect card. |
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Interestingly the router is a model at least 5 years old - a Draytek |
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Vigor, older than the 192.168.1.43 build - and it isn't replying. |
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I now realise that 3 other Linux boxes are missing from the list. I'm |
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sure I'm not the only person on the list to occasionally lose count. |
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Anyway, for each device it's either a case of: |
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- yes, it's regularly updated; |
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- sorry, there's not much to be done about it; or |
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- yes, I know it needs updating! |
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It shouldn't matter, anyway, if they're all behind a NAT router, |
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should it? I'm inclined to disable this ignore, because I do find |
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broadcast ping very occasionally useful. |
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Stroller. |
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[1] http://www.austin-hughes.co.uk/products.cfm?Product=28 |