From a different machine:
telnet <my-device-IP> <port-I-want-to-know>
Like:
telnet somehost 22
will tell you if 22 is "open"
YMMV... :)
ET
Marco Savo writes:
> Thanks, but currently I have an embedded linux board (based on openwrt) that
> use busybox, and there isn't netstat, neither nmap or lsof command. I guess
> i can read /proc/net/tcp or udp, but iptables doesn't show a list of used
> ports?
>
> On Fri, Nov 6, 2009 at 1:49 PM, Lisa Kachold <lisakachold@obnosis.com>wrote:
>
>>
>>
>> On Fri, Nov 6, 2009 at 5:30 AM, Craig White <craigwhite@azapple.com>wrote:
>>
>>> On Fri, 2009-11-06 at 13:13 +0000, Marco Savo wrote:
>>> > Hello,
>>> > configuring iptables rules,
>>> > how I can find out if one port number I want to use is already in
>>> > use?
>>> > example:
>>> >
>>> > $IPTABLES -t nat -I zone_wan_prerouting 1 -j ACCEPT --protocol udp
>>> > --dport ${UDP_PORT} --destination localhost
>>> > $IPTABLES -t nat -I zone_wan_prerouting 1 -j ACCEPT --protocol tcp
>>> > --dport ${TCP_PORT} --destination localhost
>>> > $IPTABLES -t nat -I zone_wan_prerouting 1 -j ACCEPT --protocol tcp
>>> > --dport ${TCP_HOST_PORT} --destination localhost
>>> >
>>> > How I can check if these ports (UDP_PORT TCP_PORT TCP_HOST_PORT) are
>>> > in use from another application?
>>> ----
>>> you can use netstat - for example, I might check for port 10000...
>>> # netstat -an|grep 10000
>>> tcp 0 0 0.0.0.0:10000 0.0.0.0:* LISTEN
>>> udp 0 0 0.0.0.0:10000 0.0.0.0:*
>>>
>>> Craig
>>>
>>>
>>> You can also use nmap
>>
>> # nmap localhost
>>
>> or
>>
>> # netstat -anpt
>>
>> to see what is listening on what (depending on your distro - check syntax
>>
>>
>> --
>> Skype: (623)239-3392
>> AT&T: (503)754-4452
>> www.obnosis.com
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
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>
>
>
> --
> 'The Magic Is In the Movement'
>
> Marco Savo
> SW Engineer
>
> 882 East Glenn St.
> Tucson, AZ 85719
> +1 (520) 248-5681
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