Could you look at the attached PCAP with OPTIONS message. When OPTIONS message is received, then Kamailio generates error logs like

dropping insane message from 10.140.6.38:60083

After checking the PCAP, I see extra %x00 characters after the OPTIONS message in the same UDP frame. Example [image: image.png]

I have checked RFC3261 and do not see a definition of "x00" chars. Also in the same RFC, present a reference to the RFC2234 https://datatracker.ietf.org/doc/html/rfc2234 where is described "space chars", "white space". According to RFC2223, char %x00 cannot be treated as "space" and should be treated as control (CTL) char. Also, RFC3261 does not use "CTL" chars.

Using these two RFC, I can conclude, OPTIONS in the attached PCAP breaks RFC requirements, and we can request partner fix this issue on their equipment.

Is anything else in the RFC can be used to justify that the given examples of OPTIONS messages violate RFCs?

Sergey