cannot ssh into a box with DHCP assigned IP address

Anton Shterenlikht mexas at bristol.ac.uk
Wed Feb 20 14:42:44 UTC 2013


	From ml at my.gd Wed Feb 20 14:39:34 2013

	On Feb 20, 2013, at 2:55 PM, Anton Shterenlikht <mexas at bristol.ac.uk> wrote:

	> 	From feenberg at nber.org Wed Feb 20 13:39:28 2013
	> 
	> 	> 	From: Fleuriot Damien <ml at my.gd>
	> 	> 	To: mexas at bristol.ac.uk
	> 	> 	Subject: Re: cannot ssh into a box with DHCP assigned IP address
	> 	> 	Date: Wed, 20 Feb 2013 10:31:22 +0100
	> 	> 	Cc: freebsd-questions at freebsd.org
	> 	>
	> 	> 	On Feb 20, 2013, at 10:28 AM, Anton Shterenlikht <mexas at bristol.ac.uk> wrote:
	> 	>
	> 	> 	> I have a laptop with FreeBSD -current,
	> 	> 	> with ip address assigned via DHCP.
	> 	> 	> The laptop has neither a static ip address,
	> 	> 	> nor a domain.
	> 	> 	>
	> 	> 	> I can ping the laptop fine, but cannot
	> 	> 	> ssh into it. The sshd is running, /etc/ssh/ssd_config
	> 	> 	> seems fine, /etc/hosts.allow is fine.
	> 	> 	> However, /etc/hosts is just the default:
	> 
	> 	While on the problem machine, can you ssh to localhost? ssh to the IP 
	> 	address?
	> 
	> yes to both
	> 
	> 	I would suspect the problem is in /etc/hosts.allow
	> 	 or /etc/hosts.deny,
	> 
	> The first non-comment line in /etc/hosts.allow is
	> ALL : ALL : allow
	> 
	> and I don't have /etc/hosts.deny:
	> 
	> root at zzz:~ # ls /etc/hosts*
	> /etc/hosts              /etc/hosts.equiv
	> /etc/hosts.allow        /etc/hosts.lpd
	> root at zzz:~ #
	> 
	> 	or perhaps the subnet mask is incorrect.
	> 
	> Well.. what should it be?
	> I have on the problem box (ssh server):
	> 
	> wlan0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1
	> 500
	>        ether 00:21:5c:50:68:c3
	>        inet 172.21.220.12 netmask 0xfffffc00 broadcast 255.255.255.255
	>        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
	>        media: IEEE 802.11 Wireless Ethernet OFDM/54Mbps mode 11g
	>        status: associated
	>        ssid eduroam channel 1 (2412 MHz 11g) bssid 00:3a:98:62:cd:a0
	>        country US authmode WPA2/802.11i privacy ON deftxkey UNDEF
	>        AES-CCM 2:128-bit AES-CCM 3:128-bit txpower 14 bmiss 10 scanvalid 450
	>        bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5
	>        protmode CTS wme roaming MANUAL
	> 
	> I'm trying to ssh from 137.222.187.241.
	> 
	> I wonder, perhaps it somehow built into the
	> Eduroam wireless, provided by the University,
	> that the devices connected to it cannot be
	> accessible. They can only initiate outgoing
	> connections, but all incoming connections are
	> somehow blocked? Given that the majority of
	> the devices will be unsecured MS boxes, maybe
	> the university thought that this is wise idea
	> for safety. Perhaps I can investigate this
	> with my IT guys. 
	> 
	> Or I might be talking complete nonsense here, not my area at all.
	> 
	> Thanks
	> 
	> Anton
	> 


	Any luck with Daniel's suggestion to try it directly on the problematic host ?

	ssh 127.0.0.1
	ssh localhost
	ssh 172.21.220.12

yes to all (I replied already above).

Thanks

Anton



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