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What's a fast way to check for something on LAN?
by Chris Green 22 Feb '17

22 Feb '17

I want a fast (as in less than a second, not 'computer fast') way of checking if a particular private IP is present on the LAN. I need this for use in a match construct in an SSH config file, e.g.:- # # # odin may be remote or local from t430 # Match host odin exec "sh -c 'hostNotLocal 192.168.0.104'" ProxyCommand ssh cheddar nc -q0 localhost 51234 Currently 'hostNotLocal' is:- #!/bin/bash # # # Test if specified host is ping'able # ! ping -c 1 $1 >>/dev/null 2>&1 The problem with this is that on any LAN except one using 192.168.0.xxx it takes several seconds to decide that 192.168.0.104 isn't there. For any nit-pickers, yes I know if I just happen to be connected to a LAN which isn't where 'my' 192.168.0.104 is I'll get a false positive but I can live with that. I just want a fast way of knowing that 192.168.0.104 *isn't* there. -- Chris Green

7 12

Correct MX record configuration
by Chris Green 20 Feb '17

20 Feb '17

This may relate to my recent long question about loss of E-Mail. Can anyone tell me *exactly* how an MX record for my home server zbmc.eu should be confiugured? Currently it's configured to point to the 'root' A record for zbmc.eu, so the MX record is for zbmc.eu also:- chris@cheddar$ host zbmc.eu zbmc.eu has address 84.92.49.234 zbmc.eu mail is handled by 10 zbmc.eu. chris@cheddar$ However I *think* this may be wrong and I should create a second A record for the same IP address and point the MX record to that instead. I don't really understand why this should make any diffrerence though. Any experts (or at least people who know more than me) here? -- Chris Green

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Re: [ALUG] I need an E-Mail expert to help me solve this
by Phil Ashby 19 Feb '17

19 Feb '17

On 19/02/17 12:00, Chris Green <cl(a)isbd.net> wrote: > > I have an E-Mail requirement/problem that I've wasted several hours on over the past few days to > little effect. Maybe someone here can help. > > My home (linux) machine runs all the time and hosts the domain zbmc.eu which is registered at > gandi.net. The zone file there is configured to point at my home machine and the MX record is > set up too:- > chris@cheddar$ host zbmc.eu > zbmc.eu has address 84.92.49.234 > zbmc.eu mail is handled by 10 zbmc.eu. > chris@cheddar$ 84.92.49.234 is my PlusNet ADSL connection. > > ..[lots of testing that indicates 'something' is blocking SMTP on some routes, but not all...] Hi Chris, I have almost the same setup as you, an external/public server (mail.ashbysoft.com) that forwards mail to an internal/private server at home (phil.ashbysoft.com, on PlusNet), my external server is in a co-lo facility and managed by me, rather than a 3rd part but hey, it's still working so it doesn't look like PlusNet per se.. I tried a few tests for your host: - from my home network (via NAT, PlusNet): phlash@zaphod:~$ host zbmc.eu zbmc.eu has address 84.92.49.234 zbmc.eu mail is handled by 10 zbmc.eu. phlash@zaphod:~$ telnet zbmc.eu 25 # not looking good for inbound connectivity on 25 Trying 84.92.49.234... ^C phlash@zaphod:~$ telnet zbmc.eu 587 # nor the alternative SMTP submission port 587 Trying 84.92.49.234... ^C - from my external server (via NAT, Virgin Media): phil:~$ telnet zbmc.eu 25 # still no joy Trying 84.92.49.234... ^C phil:~$ telnet zbmc.eu 587 # kind of expected by now :/ Trying 84.92.49.234... ^C phil:~$ ping zbmc.eu # just checking the endpoint is up :) PING zbmc.eu (84.92.49.234) 56(84) bytes of data. 64 bytes from chrisisbd01.plus.com (84.92.49.234): icmp_seq=1 ttl=243 time=25.2 ms 64 bytes from chrisisbd01.plus.com (84.92.49.234): icmp_seq=2 ttl=243 time=25.5 ms 64 bytes from chrisisbd01.plus.com (84.92.49.234): icmp_seq=3 ttl=243 time=21.6 ms ^C - last check for my own connectivity, to prove it's not local to me: phil:~$ telnet phil.ashbysoft.com 25 # looks OK Trying 84.92.108.193... Connected to phil.ashbysoft.com. Escape character is '^]'. 220 phil.ashbysoft.com ESMTP Exim 4.88 Sun, 19 Feb 2017 15:05:43 +0000 quit My conclusion so far would be that you have local firewalling / filtering issues that are permitting traffic from the TsoHost servers but nowhere else? Are you running fail2ban and it has been a bit enthusiastic (this has got me in the past, blocking the kids mobiles when they bork their password a couple of times)? What about port forwarding arrangements, just for specified external IPs? NB: I have switched to port 587 for all my immediate users (family & friends, you know the score!) to submit mail from their clients through my relay service, as they were finding that port 25 was blocked outbound by whatever ISP they were using at the time (typically mobile / public services like The Cloud). Hope this helps, Phil.

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Managing cron and similar E-Mails from headless systems
by Chris Green 19 Feb '17

19 Feb '17

I have several headless systems doing useful work around the place:- A Raspberry Pi providing local DNS and DHCP A Beaglebone Black on our boat monitoring temperatures and batteries An old desktop doing backups in the garage etc. Most of these have one or more cron jobs running periodic rsync backups, copying data, etc. If the cron job has an error then it sends E-Mail to the owner of the job ('chris' in most cases, might be root in a couple). It's (moderately) easy to set up an MTA and /etc/aliases so that the messages are sent to my normal E-Mail. However I can't come up with a straightforward way of indicating where the messsage is *from*. You can't just invent a domain name for the headless system because that gets the E-Mail rejected by intermediate systems that try and look up the sender host name. Cron doesn't seem to have any mechanism for setting the sender's name, cron errors just come from 'root@'. Can anyone suggest a neat way of handling this so that I know where the errors are coming from? -- Chris Green

4 11

I need an E-Mail expert to help me solve this
by Chris Green 19 Feb '17

19 Feb '17

I have an E-Mail requirement/problem that I've wasted several hours on over the past few days to little effect. Maybe someone here can help. My home (linux) machine runs all the time and hosts the domain zbmc.eu which is registered at gandi.net. The zone file there is configured to point at my home machine and the MX record is set up too:- chris@cheddar$ host zbmc.eu zbmc.eu has address 84.92.49.234 zbmc.eu mail is handled by 10 zbmc.eu. chris@cheddar$ 84.92.49.234 is my PlusNet ADSL connection. I have several domains hosted at TsoHost with associated E-Mail addresses (e.g. chris(a)isbd.co.uk, chris(a)isbd.net, cl(a)isbd.net). These all eventually forward their E-Mail from the TsoHost servers to chris(a)zbmc.eu. I run a postfix server on my home machine which receives these E-Mails and puts them in my mail spool. This has been working fine for several years. However I now want to send E-Mail from the 'outside world' to chris(a)zbmc.eu. The specific requirement is to send errors from cron on various SBCs to me and I originally thought it was a misconfiguration at the sending end was the problem but it's more general. No mail sent from outside to chris(a)zbmc.eu arrives on my home machine, it just disappears, no errors, no bounces, nothing. Bit it works from the TsoHost cloud servers, why can they send E-Mail successfully to chris(a)zbmc.eu whereas no one else can? I have done lots of tests and experiments so far:- I've tried sending from three different sites (PlusNet, Gandi and a Linux box) to chris(a)zbmc.eu, mail just disappears. Identical E-Mail sent to chris(a)isbd.net arrives OK. I have a postfix server set up on my Beaglebone black in France (to send the cron messages). If I monitor the mail.log file when connecting to the SMTP server at TsoHost (mail3.gridhost.co.uk) the logging is exactly the same for mails sent to chris(a)zbmc.eu as for mails sent to chris(a)isbd.net. Wierdly (and this is what confused me somewhat at the start) I have an identical postfix setup on a Raspberry Pi on my home LAN, also for sending cron errors. It connects directly to the same SMTP server at TsoHost as the Beaglebone does. However E-Mail to chris(a)zbmc.eu from the Pi works! So it would seem that there's something 'out there' that's routing mail for zbmc.eu to the wrong place (or nowhere), but it doesn't get at the mail sent from within TsoHost for some reason. I.e. TsoHost seems to do what I hoped/expected with E-Mail for chris(a)zbmc.eu but no one else does. Help! :-) -- Chris Green

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Re: [ALUG] Managing cron and similar E-Mails from headless systems
by mark fernandes 17 Feb '17

17 Feb '17

Looks live reverse alias are what you need... https://linux.die.net/man/8/ssmtp

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[ALUG Announce] ALUG Norwich Pub Meet Thursday 9th February
by Viperfang 06 Feb '17

06 Feb '17

ALUG Announce Please send announcements to Announce(a)lists.alug.org.uk Unsub, change settings via https://lists.alug.org.uk/mailman/listinfo/announce ----- Hello Norwich Aluggers, Our monthly ALUG Norwich social meeting will be held this Thursday, 9th February at The Coach and Horses (82 Thorpe Road, Norwich, NR1 1BA). The meeting officially starts at 8pm, although some people may arrive earlier. More information on those people can be found on the list and the IRC channel. If you are unsure if you will recognise us then make yourself and your intent to attend known by either posting on list or visiting us on IRC so we can look out for you rather than hiding in the corner. Optionally you could ask at the bar if they know where the geeky computer weirdos are and they'll point you in the right direction (seriously!). Another possibility is look for heaps of electronics on a table that may possibly look like movie props that would used for detonating explosives. Feel free to bring electronics/laptops/gadgets to the meet, you will by no means be alone. Ben Bewick aka Viperfang NB: This mail is automated, please refer to the usual sources for more information. ALUG Contact Details: Website : http://www.alug.org.uk/ IRC : #alug on irc.alug.org.uk List : http://lists.alug.org.uk/mailman/listinfo Twitter : http://twitter.com/anglianlug Identica: TBA Facebook: http://www.facebook.com/group.php?gid=2381613902 ----- Send discussion replies to main(a)lists.alug.org.uk (Reply-To set) Unsub, change settings via https://lists.alug.org.uk/mailman/listinfo/announce

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2600 meeting at 18:00 on Friday the 3rd February.
by Viperfang 31 Jan '17

31 Jan '17

Quick heads up about this months Norwich 2600 meeting, more info at http://www.norwich2600.co.uk

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How to get rid of these corrupted files?
by Chris Green 28 Jan '17

28 Jan '17

I have some files/directories which have obviously become corrupted. The disk checks out OK with fsck though and I don't want to reformat it. One of the directories in question is as follows:- total 40 d-wxr-S-wT 2 3775186858 3662599049 4096 Sep 11 1991 18039.dat ---xr-srwT 30 3023870906 1270584165 45056 Mar 1 1938 18591.dat -r-x-wxr-T 30 2743781339 1057221377 28672 Jun 6 1929 18684.dat Even as root I can't seem to do anything with this, both rm and chmod fail with 'permission denied'. So, how do I do anything with these? -- Chris Green

2 6

Wanted - plain, simple, GUI address book
by Chris Green 28 Jan '17

28 Jan '17

I use mutt for E-Mail but I'm looking for a GUI address book because my address book requirements extend well beyond (but include) E-Mail addresses for mutt. I have been using the Contacts app in Owncloud with pycardsyncer keeping a local address list in sync with the Owncloud Contacts for mutt to use. However I'd like to make things simpler and better, the existing set-up has some disadvantages (for me) :- The Owncloud Contacts app is not very good, in particular you can't sort by Last Name which really bugs me. I'd really prefer to keep addresses wholly locally rather than on the cloud (even though it's my own cloud). Apart from anything else I'm quite often not able to access the internet and I still want my addresses and to be able to update them. The pycardsyncer (plus pc_query) application is 'deprecated', it's being superseded by vcardsyncer and some other bits and pieces. They're not in the Ubuntu repositories though and I prefer not to go 'ex repository'. The current set up is a fairly complicated way to fulfil a simple requirement. So I'm after a nice, simple, GUI address book program for my Linux desktop and laptop. I'm happy to use a mail program whose address book is easily accessible without navigating past the mail bit (e.g. like Thunderbird, but Thunderbird is overkill). I either want a mutt accessibility option or for the data to be kept in something sensible like a sqlite database that I can quickly write a simple script for to feed mutt. It must support postal addresses, phone numbers, etc. and preferably have some notes/comments ability too. I'd prefer something in the Ubuntu repositories though something in Python that I can maintain myself is also OK. Any suggestions anyone? -- Chris Green

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