[Nottingham] How to enable echo (for ping)

[Martin]

Martin wrote:
> James Beckett wrote:
> 
[...]
>> The echo service will echo back a TCP stream
>> you send to it, eg with
>>     telnet localhost echo
>> More than likely, you don't need it enabled.
> 
> Beautifully obscure! I'll have a brief play before disabling it...
> 
[...]
>> Can you telnet localhost?
>>         telnet localhost 80? etc

Telnet now installed (:-))

And:

# telnet localhost 80
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused


... But then that is probably iptables rightly doing its stuff.

"Now to move right along..." (Very famous quote (:-))


[...]
>> In /etc/sysctl.conf do you have a line like
>>     net.ipv4.icmp_echo_ignore=1 ?
> 
> 
> Got one better than that!
> 
> How about:
> net.ipv4.icmp_echo_ignore_all=1
> 
> (:-))
> 
> Now for a few more tweaks, including
> net.ipv4.icmp_echo_ignore_all=0


# vim sysctl.conf
# sysctl -p
# ping localhost
PING localhost (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.071 ms
64 bytes from localhost (127.0.0.1): icmp_seq=2 ttl=64 time=0.087 ms
64 bytes from localhost (127.0.0.1): icmp_seq=3 ttl=64 time=0.068 ms
64 bytes from localhost (127.0.0.1): icmp_seq=4 ttl=64 time=0.090 ms
64 bytes from localhost (127.0.0.1): icmp_seq=5 ttl=64 time=0.097 ms
64 bytes from localhost (127.0.0.1): icmp_seq=6 ttl=64 time=0.091 ms
64 bytes from localhost (127.0.0.1): icmp_seq=7 ttl=64 time=0.090 ms
64 bytes from localhost (127.0.0.1): icmp_seq=8 ttl=64 time=0.073 ms
64 bytes from localhost (127.0.0.1): icmp_seq=9 ttl=64 time=0.066 ms
64 bytes from localhost (127.0.0.1): icmp_seq=10 ttl=64 time=0.099 ms

--- localhost ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9027ms
rtt min/avg/max/mdev = 0.066/0.083/0.099/0.013 ms


All good stuff!

Now I just need to find what bit of script rewrites sysctl.conf undoing 
my net.ipv4.icmp_echo_ignore_all=0 fix...


> Many thanks!
> 
> Martin
> (And where in manuals is there a pointer to that!)



-- 
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Martin Lomas
martin@ml1.co.uk
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