System SNMP error - SNMP::get(): No response from <remote host>

[CptnBlues63]

I found the following post regarding this same issue:

viewtopic.php?t=62555

But I wanted to start a new thread because that one appeared to have never been resolved.

I'm in the same situation. I have over 100 switches I'm trying graph and on all but 3, I've successfully created devices and graphs. But on 3 of them I get the above error message when I try to create a "device" in Cacti.

All switches are using SNMP v2
There are no restrictions on the firewalls
There are no restrictions on the devices.

I tried the following command: time snmpgetnext -c blah -v2c hostname .1.3 as requested by "TheWitness" in the other string but when I replace "hostname" with the IP or hostname of the switches it just errors out so I must be doing the command incorrectly.

My management software uses SNMP to connect to the switches and also to perform nightly backups. It's been connecting perfectly for years.

All switches have the exact same SNMP configuration and in fact, on the 3 that aren't working properly I've gone in and redone the community strings a couple times to no avail. Cacti still can't seem to connect.

I would really like this to work so I'm looking for some help. If there's any more information you need, or commands I can run I'd be more than happy to.

TIA

[macan]

snmpwalk -c your_community -v2c hostname

You have to change your_community to correct string.

Is firmware of switches same?

[CptnBlues63]

snmpwalk -c your_community -v2c hostname

You have to change your_community to correct string.

Is firmware of switches same?

Thanks for the response.

I tried your snmpwalk command and had to hit ctrl-c quickly and in a matter of a couple seconds it spewed pages of info. Here's a couple of the first lines that returned:

iso.3.6.1.2.1.1.1.0 = STRING: "Ethernet Routing Switch 5952GTS-PWR+ HW:08 FW:7.5.0.4 SW:v7.9.2.017 BN:17 (c) Extreme Networks"
iso.3.6.1.2.1.1.2.0 = OID: iso.3.6.1.4.1.45.3.81.4
iso.3.6.1.2.1.1.3.0 = Timeticks: (2806671947) 324 days, 20:18:39.47
iso.3.6.1.2.1.1.4.0 = STRING: "ITS Infrastructure Dept"
iso.3.6.1.2.1.1.5.0 = STRING: "AUC5961"
iso.3.6.1.2.1.1.6.0 = STRING: "CC06"
iso.3.6.1.2.1.1.7.0 = INTEGER: 6
iso.3.6.1.2.1.2.1.0 = INTEGER: 52
iso.3.6.1.2.1.2.2.1.1.1 = INTEGER: 1
iso.3.6.1.2.1.2.2.1.1.2 = INTEGER: 2
iso.3.6.1.2.1.2.2.1.1.3 = INTEGER: 3
iso.3.6.1.2.1.2.2.1.1.4 = INTEGER: 4

I use a different command to test SNMP and it is as follows:

snmpwalk -Os -c [community] -v 2c [host] 1.3.6.1.2.1.1.1

Where "community" is my password (in this case RO, read only) and "host" is the IP of the switch. All 3 are returning the same, positive, response:

iso.3.6.1.2.1.1.1.0 = STRING: "Ethernet Routing Switch 5952GTS-PWR+ HW:08 FW:7.5.0.4 SW:v7.9.2.017 BN:17 (c) Extreme Networks"
iso.3.6.1.2.1.1.1.0 = STRING: "Ethernet Routing Switch 59100GTS-PWR+ HW:08 FW:7.5.0.4 SW:v7.9.2.017 BN:17 (c) Extreme Networks"
iso.3.6.1.2.1.1.1.0 = STRING: "Ethernet Routing Switch 5952GTS-PWR+ HW:08 FW:7.5.0.4 SW:v7.9.2.017 BN:17 (c) Extreme Networks"

The above are the returns from all 3 switches. The only real difference between the 3 is that one of them is a high density 100 port switch. The others are your typical 52's (counts include fiber uplinks so the 100 has 96 RJ-45's and the 52 has 48). I've used this command extensively troubleshooting SNMP issues and when there is a problem with SNMP on the switch, it returns nothing so I know that SNMP is working on the switches. Also, my management software "sees" the switches. They don't appear in it if SNMP doesn't work.

Yes, all my switches are on the same revision of software/firmware.

[macan]

are you trying snmpwalk directly from cacti server?

If no, It could be routing issue (missing route or default gateway on switches).

If yes, try to delete these 3 switches from cacti and add it again. I met this issue sometimes.

[CptnBlues63]

are you trying snmpwalk directly from cacti server?

If no, It could be routing issue (missing route or default gateway on switches).

If yes, try to delete these 3 switches from cacti and add it again. I met this issue sometimes.

Oh boy do I feel sheepish now..........LOL

I was doing that snmpwalk from my switch management server (also linux). I just tried it from my cacti server and it's not getting a response from those three switches. It is from the other switches.

I've just looked at the configuration and it's the same as the other switches. They have an IP, subnet mask and default gateway, all correct. We didn't bother putting routes on these because they're all on the same subnet which is isolated from the rest of our network.

All 3 switches respond to ping requests from the cacti server.

So what should I look at now?

[macan]

Routing table on switches, routing table on cacti, firewall/ip restriction os switches, firewall on cacti, ...
And to all devices between cacti and switches.

Packet sniffer could help.

[CptnBlues63]

Routing table on switches, routing table on cacti, firewall/ip restriction os switches, firewall on cacti, ...
And to all devices between cacti and switches.

Packet sniffer could help.

I'll do some checking and see if maybe there's some kind of firewall issue interfering with those 3 switches.

[CptnBlues63]

Routing table on switches, routing table on cacti, firewall/ip restriction os switches, firewall on cacti, ...
And to all devices between cacti and switches.

Packet sniffer could help.

Packet sniffing shows the switches not responding to SNMP requests from the Cacti server. But they do respond to pings. So I'm opening a ticket with our vendor to have them help look into it.

Thanks for all the troubleshooting help. If we resolve it, I'll post at the end of this thread what was wrong and what the resolution was.

[Osiris]

If php-snmp is installed, uninstall it and then restart httpd/apache and php-fpo is installed

[CptnBlues63]

If php-snmp is installed, uninstall it and then restart httpd/apache and php-fpo is installed

Thanks for the input. I'd like to try that. What command would I use to check if php-snmp is installed?

Thanks

[macan]

php -m

[CptnBlues63]

php -m

Output of the aforementioned command below:

root@ip-xxx-xxx-xxx-xxx bin]# php -m
[PHP Modules]
bz2
calendar
Core
ctype
curl
date
dom
exif
fileinfo
filter
ftp
gd
gettext
gmp
hash
iconv
intl
json
ldap
libxml
mbstring
mysqli
mysqlnd
openssl
pcntl
pcre
PDO
pdo_mysql
pdo_sqlite
Phar
posix
readline
Reflection
session
shmop
SimpleXML
snmp
sockets
SPL
sqlite3
standard
sysvmsg
sysvsem
sysvshm
tokenizer
wddx
xml
xmlreader
xmlwriter
xsl
zlib

[Zend Modules]

Now I will happily confess I know nothing about php but I'm guessing the fact that there was output is indicative that php is installed and running. Correct?

[Osiris]

Dependent upon your OS distribution there will be a package called php-snmp. You simply have to remove that RPM package or Debian package and then restart Apache.

[CptnBlues63]

Dependent upon your OS distribution there will be a package called php-snmp. You simply have to remove that RPM package or Debian package and then restart Apache.

I should maybe mention that this is on a server located on the cloud (AWS to be precise) and their linux is tweaked and controlled by them

[root@ip-172-xx-xx-xx bin]# uname -a
Linux ip-172-19-80-42.ec2-internal 4.18.0-425.19.2.el8_7.x86_64 #1 SMP Fri Mar 17 01:52:38 EDT 2023 x86_64 x86_64 x86_64 GNU/Linux
[root@ip-172-xx-xx-xx bin]#

Their flavor of linux doesn't have "apt" so I had to use yum to try to remove php-snmp. I tried but it wanted to get rid of cacti and a couple other dependencies. (See screenshot attached) so I told it no. Some research lead me to this thread regarding removing php-snmp and the OP had a similar dependency issue:

http://forums.cacti.net/viewtopic.php?t=62343

Specifically this response: Unread post by macan » Tue Oct 11, 2022 12:59 am suggested renaming the php-snmp. Will that work? If so I'd be happy to try it. Sadly, AWS linux doesn't have "locate" but using find I got this:

root@ip-172-xx-xx-xx bin]# find / -name snmp.so
/usr/lib64/php/modules/snmp.so
[root@ip-172-xx-xx-xx bin]#

Just to confirm, renaming that snmp.so file should do the trick?

Alternatively, is there a way, using "yum" to remove php-snmp without removing it's dependencies? I'm not overly familiar with yum or apt.

Thanks for all the help btw....I appreciate it!

[CptnBlues63]

Ok, the above didn't work. I still can't create graphs on the 3 switches affected by this issue *sighing*