> For the complete documentation index, see [llms.txt](https://gsm-hacking.telco-sec.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gsm-hacking.telco-sec.com/2g-in-a-b0x/sgsn-serving-gprs-support-node.md).

# SGSN - Serving GPRS Support Node

```
sudo vi  /etc/osmocom/osmo-sgsn.cfg
```

```
!
! Osmocom SGSN configuration
!
!
line vty
 no login
!
sgsn
 gtp local-ip 127.0.0.1
 ggsn 0 remote-ip 127.0.0.6
 ggsn 0 gtp-version 1
! auth-policy closed
! accept-all, closed, acl-only, remote
 auth-policy accept-all
ns
 timer tns-block 3
 timer tns-block-retries 3
 timer tns-reset 3
 timer tns-reset-retries 3
 timer tns-test 30
 timer tns-alive 3
 timer tns-alive-retries 10
 encapsulation udp local-ip 127.0.0.1
 encapsulation udp local-port 23000
 encapsulation framerelay-gre enabled 0
!
bssgp
!

```