Thank you both for your replies. Client followed some of mine guidelines and has proven that the issue is with the Fortinet F5 firewall: he made a snapshot of the kamailio node #2 that we know is 100% working, installed the snapshot, modified the IPs, and made tests, and the behaviour is identical to node #1. The relevant question is why node #2, who has the same rules as node #1, is working fine, but not nodes #1 and #3 ?! doesn't make much sense... Meanwhile, client has been dealing with the issue with Fortinet's engineering team. Looks like a firmware issue... Atenciosamente / Kind Regards / Cordialement / Un saludo, *Sérgio Charrua* On Wed, Sep 18, 2024 at 10:35 PM Karsten Horsmann <khorsmann(a)gmail.com> wrote:

Hi Sérgio I've dealt with these sorts of problems before. This can get very complicated/confusing. It doesn't make sense to me that _enabling_ the RPF fixed it; I'd expect it to be the other way around: disabling it should help. I've noticed Linux machines doing funny things in the past with answering ARP queries from "wrong" interfaces. If I have ip1 on eth1 and ip2 on eth2, and an ARP comes for ip2 on eth1, then I've seen a response there. It's possible that your two firewalls send traffic to different network interfaces on the machine, and that's what leads to the issue. That's my best guess. It might be simply a matter of time before you see the same problem on the machine that has had no problems yet. If I was to troubleshoot this further, I'd set up network captures separately (for ARP and SIP) on the three network interfaces and see what happens. That might tell you more, and you might see traffic on a "wrong" interface. It can be complicated if VLANs are involved or if a subnet mask is set incorrectly by mistake, etc. (Before you mentioned the cause, I could have suspected fragmentation, as Henning mentioned. An ALG might wreck a message so much that the UDP length or UDP checksum might be wrong, so I would capture traffic and check those in Wireshark. If the checksum is wrong, then kamailio will never even see the message.) James On Thu, 19 Sept 2024 at 14:29, Sergio Charrua via sr-users <sr-users(a)lists.kamailio.org> wrote:

Do you have DEBUG log levels enabled? If so, do you not see INVITE transactions in the logs? ________________________________ From: Andrew R Miller via sr-users &lt;sr-users(a)lists.kamailio.org&gt; Sent: Thursday, September 19, 2024 4:30 AM To: Kamailio (SER) - Users Mailing List &lt;sr-users(a)lists.kamailio.org&gt; Cc: Andrew R Miller &lt;Andrew.Miller(a)gamma.co.uk&gt; Subject: [SR-Users] Re: Kamailio not listening to SIP despite setup OK [EXTERNAL] Hi Sergio, Just a guess, but it’s not a Reverse Path Forwarding issue is it? This has been my problem in the past where I can see the packets in a tcpdump (and therefore probably in sngrep), but never saw them in the application. Check the source addresses of the OPTIONS compared to the INVITE, and the route settings on the two Kamailio servers… Andrew Andrew R Miller UCaaS Technical Lead Tel: 0333 043 9991<tel:0333%20043%209991> Mobile: 07458 014 638<tel:07458%20014%20638> Email: Andrew.Miller@gamma.co.uk<mailto:Andrew.Miller@gamma.co.uk> [cid:image679898.jpg@D3FC63C4.D64566DD] [cid:image234571.jpg@1E2F5512.3BBC9C30] [cid:image350760.jpg@5C2F1288.3FAE49F3] [cid:image122190.png@2F4D5938.148FA5B3] This is an email from Gamma Telecom Ltd, trading as “Gamma”. The contents of this email are confidential to the ordinary user of the email address to which it was addressed. This email is not intended to create any legal relationship. No one else may place any reliance upon it, or copy or forward all or any of it in any form (unless otherwise notified). If you receive this email in error, please accept our apologies, we would be obliged if you would telephone our postmaster on +44 (0) 808 178 9652 or email postmaster(a)gamma.co.uk Gamma Telecom Limited, a company incorporated in England and Wales, with limited liability, with registered number 04340834, and whose registered office is at The Scalpel, 18th Floor, 52 Lime Street, London EC3M 7AF and whose principal place of business is at Kings House, Kings Road West, Newbury, Berkshire, RG14 5BY. From: Karsten Horsmann via sr-users &lt;sr-users(a)lists.kamailio.org&gt; Sent: 18 September 2024 21:36 To: Kamailio (SER) - Users Mailing List &lt;sr-users(a)lists.kamailio.org&gt; Cc: Karsten Horsmann &lt;khorsmann(a)gmail.com&gt; Subject: [SR-Users] Re: Kamailio not listening to SIP despite setup OK Hi Sergio, You answer the right questions. Works it before, yes. Changed the Kamailio system, no. So it's an Fortinet fault. By painful experience with Cisco and Fortinet stuff I know that you need to tweak the Fortnite (SIP ALG, SIP POLICY and so one). Go in that direction cause it works with Cisco before and the Fortigate seems to break it. Kind regards Sergio Charrua via sr-users <sr-users@lists.kamailio.org<mailto:sr-users@lists.kamailio.org>> schrieb am Mi., 18. Sept. 2024, 10:19: Hi all! got a client with 2 Kamailio servers using Pacemaker/Corosync with a VIP. Kamailio is setup with dispatcher, and has been working since 2018. This previous week, client migrated from a Cisco ASA firewall to a Fortinet F5 firewall. One of the Kamailio server is, apparently, working fine, receiving SIP invites and processing them correctly. When moving the VIP to the second Kamailio node, Kamailio is ignoring any SIP message that is not OPTIONS, despite configuration (kamailio.cfg) being exactly the same as in the node #1. Also, note that using SNGrep, we can see clearly that SIP messages are reaching the server, but Kamailio is just not processing any INVITE. In fact, I added an output to log file right at the very beginning of the main route and the line is added to log file ONLY if the SIP message is OPTIONS. When the SIP message is INVITE, nothing is processed on Kamailio's side. The listen parameter is set to 0.0.0.0 port 5060 and advertised IP set to the Public IP. Again, the main route is only : route{ xlog(. ......); } Kamailio version is 5.1.6 (old, I know....) but it has been working since Dec 2018! What could be the issue?! Why only OPTIONS are being , somehow, recognized by Kamailio and all other SIP messages just ignored? Also, to add some more weirdness to the mess, connecting an Asterisk server on the same network, and sending a call to Kamailio node #2, it works!! SIP messages of any kind are processed correctly by Kamailio on node #2. So, why doesn't it work with SIP messages received via Public IP address, even though the messages reach the server correctly (confirmed using SNGrep) ??? I spent 5h this afternoon trying to understand what is wrong, but I'm stuck .... and no clue so far, apart from suspecting of the new Gateway, which I have no access to configurations.... but if OPTIONS are received & processed OK, it wouldn't make sense that received INVITES would be ignored by Kamailio, right? Atenciosamente / Kind Regards / Cordialement / Un saludo, Sérgio Charrua __________________________________________________________ Kamailio - Users Mailing List - Non Commercial Discussions To unsubscribe send an email to sr-users-leave@lists.kamailio.org<mailto:sr-users-leave@lists.kamailio.org> Important: keep the mailing list in the recipients, do not reply only to the sender! Edit mailing list options or unsubscribe: