The main question:
My Asterisk logs are littered with messages like these:
[2012-05-29 15:53:49] NOTICE[5578] chan_sip.c: Registration from '<sip:
[email protected]>' failed for '37.75.210.177' - No matching peer
found
[2012-05-29 15:53:50] NOTICE[5578] chan_sip.c: Registration from '<sip:
[email protected]>' failed for '37.75.210.177' - No matching peer
found
[2012-05-29 15:53:55] NOTICE[5578] chan_sip.c: Registration from '<sip:
[email protected]>' failed for '37.75.210.177' - No matching peer
found
[2012-05-29 15:53:55] NOTICE[5578] chan_sip.c: Registration from '<sip:
[email protected]>' failed for '37.75.210.177' - No matching peer
found
[2012-05-29 15:53:57] NOTICE[5578] chan_sip.c: Sending fake auth rejection for device <sip:
[email protected]>;tag=cb23fe53
[2012-05-29 15:53:57] NOTICE[5578] chan_sip.c: Sending fake auth rejection for device <sip:
[email protected]>;tag=cb23fe53
[2012-05-29 15:54:02] NOTICE[5578] chan_sip.c: Registration from '<sip:
[email protected]>' failed for '37.75.210.177' - No matching peer
found
[2012-05-29 15:54:03] NOTICE[5578] chan_sip.c: Registration from '<sip:
[email protected]>' failed for '37.75.210.177' - No matching peer
found
[2012-05-29 21:20:36] NOTICE[5578] chan_sip.c: Registration from '"55435217"<sip:
[email protected]>' failed for '65.218.221.180' - No matching peer
found
[2012-05-29 21:20:36] NOTICE[5578] chan_sip.c: Registration from '"1731687005"<sip:
[email protected]>' failed for '65.218.221.180' - No matching peer
found
[2012-05-30 01:18:58] NOTICE[5578] chan_sip.c: Sending fake auth rejection for device "unknown" <sip:
[email protected]>;tag=dEBcOzUysX
[2012-05-30 01:18:58] NOTICE[5578] chan_sip.c: Sending fake auth rejection for device "unknown" <sip:
[email protected]>;tag=9zUari4Mve
[2012-05-30 01:19:00] NOTICE[5578] chan_sip.c: Sending fake auth rejection for device "unknown" <sip:
[email protected]>;tag=sOYgI1ItQn
[2012-05-30 01:19:02] NOTICE[5578] chan_sip.c: Sending fake auth rejection for device "unknown" <sip:
[email protected]>;tag=2EGLTzZSEi
[2012-05-30 01:19:04] NOTICE[5578] chan_sip.c: Sending fake auth rejection for device "unknown" <sip:
[email protected]>;tag=j0JfZoPcur
[2012-05-30 01:19:06] NOTICE[5578] chan_sip.c: Sending fake auth rejection for device "unknown" <sip:
[email protected]>;tag=Ra0DFDKggt
[2012-05-30 01:19:08] NOTICE[5578] chan_sip.c: Sending fake auth rejection for device "unknown" <sip:
[email protected]>;tag=rR7q7aTHEz
[2012-05-30 01:19:10] NOTICE[5578] chan_sip.c: Sending fake auth rejection for device "unknown" <sip:
[email protected]>;tag=VHUMtOpIvU
[2012-05-30 01:19:12] NOTICE[5578] chan_sip.c: Sending fake auth rejection for device "unknown" <sip:
[email protected]>;tag=JxZUzBnPMW
I use Asterisk for an automated phone system. The only thing it does is receives incoming calls and executes a Perl script. No outgoing calls, no incoming calls to an actual phone, no phones registered with Asterisk.
It seems like there should be an easy way to block all unauthorized registration attempts, but I have struggled with this for a long time. It seems like there should be a more effective way to prevent these attempts from even getting far enough to reach my Asterisk logs. Some setting I could turn on/off that doesn't allow registration attempts at all or something. Is there any way to do this?
Also, am I correct in assuming that the "Registration from ..." messages are likely people attempting to get access to my Asterisk server (probably to make calls on my account)? And what's the difference between those messages and the "Sending fake auth rejection ..." messages?
Further detail:
I know that the "Registration from ..." lines are intruders attempting to get access to my Asterisk server. With Fail2Ban set up, these IPs are banned after 5 attempts (for some reason, one got 6 attempts, but w/e).
But I have no idea what the "Sending fake auth rejection ..." messages mean or how to stop these potential intrusion attempts. As far as I can tell, they have never been successful (haven't seen any weird charges on my bills or anything).
Here's what I have done:
Set up hardware firewall rules as shown below. Here, xx.xx.xx.xx is the IP address of the server, yy.yy.yy.yy is the IP address of our facility, and aa.aa.aa.aa, bb.bb.bb.bb, and cc.cc.cc.cc are the IP addresses that our VoIP provider uses. Theoretically, ports 10000-20000 should only be accessible by those three IPs.+-------+-----------------------------+----------+-----------+--------+-----------------------------+------------------+
| Order | Source Ip | Protocol | Direction | Action | Destination Ip | Destination Port |
+-------+-----------------------------+----------+-----------+--------+-----------------------------+------------------+
| 1 | cc.cc.cc.cc/255.255.255.255 | udp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 10000-20000 |
| 2 | any | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 80 |
| 3 | any | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 2749 |
| 4 | any | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 443 |
| 5 | any | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 53 |
| 6 | any | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 1981 |
| 7 | any | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 1991 |
| 8 | any | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 2001 |
| 9 | yy.yy.yy.yy/255.255.255.255 | udp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 137-138 |
| 10 | yy.yy.yy.yy/255.255.255.255 | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 139 |
| 11 | yy.yy.yy.yy/255.255.255.255 | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 445 |
| 14 | aa.aa.aa.aa/255.255.255.255 | udp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 10000-20000 |
| 17 | bb.bb.bb.bb/255.255.255.255 | udp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 10000-20000 |
| 18 | any | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 1971 |
| 19 | any | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 2739 |
| 20 | any | tcp | inbound | permit | xx.xx.xx.xx/255.255.255.255 | 1023-1050 |
| 21 | any | all | inbound | deny | any on server | 1-65535 |
+-------+-----------------------------+----------+-----------+--------+-----------------------------+------------------+
Set up Fail2Ban. This is sort of working, but it's reactive instead of proactive, and doesn't seem to be blocking everything (like the "Sending fake auth rejection ..." messages).
Set up rules in sip.conf to deny all except for my VoIP provider. Here is my sip.conf with almost all commented lines removed (to save space). Notice at the bottom is my attempt to deny all except for my VoIP provider:[general]
context=default
allowguest=no
allowoverlap=no
bindport=5060
bindaddr=0.0.0.0
srvlookup=yes
disallow=all
allow=g726
allow=ulaw
allow=alaw
allow=g726aal2
allow=adpcm
allow=slin
allow=lpc10
allow=speex
allow=g726
insecure=invite
alwaysauthreject=yes
;registertimeout=20
registerattempts=0
register = user:pass:
[email protected]:5060/700
[mysipprovider]
type=peer
username=user
fromuser=user
secret=pass
host=sip.mysipprovider.com
fromdomain=sip.mysipprovider.com
nat=no
;canreinvite=yes
qualify=yes
context=inbound-mysipprovider
disallow=all
allow=ulaw
allow=alaw
allow=gsm
insecure=port,invite
deny=0.0.0.0/0.0.0.0
permit=aa.aa.aa.aa/255.255.255.255
permit=bb.bb.bb.bb/255.255.255.255
permit=cc.cc.cc.cc/255.255.255.255
